Top 10 Sniper EFI Installation Tips from Holley's Tom Kise

Posted by Chris Myer 08/11/17 44 Comment(s) Sniper and Terminator X,

Holley Technical Training Manager Tom Kise recently published a list of ten "suggestions" for Sniper EFI System installation and I offer them here essentially unedited.  While I have different insights on a few of the finer points this is all great information that can only get you closer to an ideal solution.  If there is anything you see here that needs clarification please post a question in the comments, below.

#1 READ

Read the instructions and Follow them. If you do not understand a step seek assistance. (Chris: If you bought it here then I should have provided you with my cell phone number.  Don't hesitate to call, nights and weekends included.)

#2 Wire It Properly

Most important!!! MAIN POWER AND GROUND need to go to the battery. Directly to the BATTERY!!! Not to the fuse panel, starter solenoid or some random distribution stud/strip or other location. Direct to the battery means to the battery. Make sure you are using proper wiring practices. Incorrect connections will result in excessive resistance. Resistance results in heat and heat results in more resistance. A common issue we see is a result of poor fuel pump grounding running a eyelet from the pump ground to a rusty or painted surface. The resulting resistance can burn up fuel pumps, wiring and relays. Extending wires with too small of a wire gauge will also result in the same damage.

#3 Engine Ground

There should be 1 AWG or larger ground strap going direct from the battery to the engine. Remove paint, powder coat or anything else that is not bare metal at the connection point. Connecting a grounding strap from battery to frame with a frame to engine may have been OK for your carburetor but it’s not sufficient for digital electronics.

#4 Ignition parts

You need to run resistor plugs and resistor, non-solid core wires. Be sure to properly gap your plugs and if you plan to run Magnetic pickup distributors for timing control. You also need to properly phase the rotor. Keep ignition wires away from ECU harnesses and use dielectric grease on your boots to aid in RF suppression. If you have RF and or EMI issues you need to correct them. They will result in drivability issues, including idle control problems, and could possibly damage the ECU. Have you ever watched a post nuclear apocalypse movie? EMI is what wipes out all the electronics. Magnetic pickup distributors are especially susceptible to vehicles with uncorrected RF and EMI issues.

#5 O2 sensors

The Sniper ships with an OEM grade Bosch O2 sensor. Not some generic piece as some have speculated. Oxygen sensors read unburnt Oxygen not Fuel. All it knows is what it sees in the pipe. When a wide band sensor is (DAMAGED) it almost always reads dead lean. Why? Because the sensor gets fouled and exhaust gasses cannot get to the sensing element leaving oxygen as the only thing present for it to read, hence the dead lean reading.

So, what damages O2 sensors?

  • Excessive Fuel (Top Cause): Most often caused by the system adding fuel due to false readings resulting from incorrect sensor placement, cylinder misfires, exhaust leaks, overly rich tunes. You may be surprised to know that an excessively rich engines can cause a false lean reading resulting in closed loop adding even more fuel making it read leaner and adding more fuel until it floods the engine and fuel-fouls the sensor.
  • Oil control: If you're burning oil you will kill your O2 sensor, closed loop chasing unstable fuel supply issues( see fuel pumps comment)
  • Wrong Sealants or Fuel Additives: Those that are not O2 sensor safe will kill your sensor.
  • O2 Sensor Mounting: The O2 needs to be mounted 6-8” after the merge in the header collector. It needs the tip pointed down at least 10 degrees from horizontal and at least 15 degrees from vertical I prefer about a 45 degree angle from horizontal. You should then have at least 18-24” of pipe after the sensor. If you have any exhaust leaks between the combustion chamber and 18-24” after the sensor you are going to have problems.
  • Pinched or Burnt O2 sensor Wiring: Keep it high, tight, and safe. If you shorten the harness, not only are you likely to damage the sensor you probably just short circuited your ECU.

#6 Fuel pumps

The sniper master kits ship with OEM grade 255 LPH Walbro Pumps. Not some generic pump as some have speculated. Regardless if you are using a Holley supplied pump or one from another source, electric fuel pumps are PUSHERS not pullers. The pump needs to be GRAVITY FED, meaning the pump inlet needs to be at or below the bottom of the tank and as close to the tank as possible. This is why most OEM EFI pumps are in the tank. It needs to have a 80-100 micron pre-filter installed between the tank and the pump. And 10 micron filter between the pump and throttle body.

Avoid using any 90 degree fittings between the tank and pump. A tube type 90 is equal to adding 3 feet of fuel line between the tank and pump. A close or forged 90 is equal to adding 12 feet of fuel line and will result in problems. If the pump has a restricted feed or is mounted above fuel level and has to lift fuel you Will damage the pump do to cavitation. Most current pump fuels boil around 130 degrees. Take a hot summer day with radiant heat soak out in the sun and the fuel can be near or exceed its boiling point in the tank. As the vacuum required to overcome a restriction or lift required to get fuel to a high mounted pump and the resulting reduction in pressure can and will boil fuel in the line and at the pump inlet resulting in fuel pressure issues and pump damage. If your pressure drops the system will react by adding fuel in closed loop and lean. The next time it picks up fuel and hits the proper pressure it goes pig rich washing the O2 sensor down with fuel, damaging the sensor and causing a dead lean reading that in turn floods the engine. The resulting O2 sensor failure is damaged not defective.

How did you install the return line to the tank? If you free dumped it in the top, it will aerate and foam up the fuel. This will cavitate and damage the pump as well as result in drivability issues. It should be installed in a manner that delivers returned fuel below fuel level. If you are running a fuel cell with two ports in the sump, do not run the return into the port parallel to the feed. Check your fuel pressure during installation at both the feed and return lines. Feed pressure should be knocking on 58 PSI and the return should ideally be zero, if the feed pressure is not correct, or if the return line pressure is greater than 4-5 PSI find and correct the restriction before proceeding.

#7 Idle / IAC

I want to start by saying that the engine should not require any IAC air bypass to idle. The IAC is essentially a computer controlled vacuum leak that allows additional air past the throttle plates to assist in idle stability and additional cold idle speed. With the engine at full operating temperature you should be able to stick your finger in the IAC inlet port on top of the throttle body and the engine should simply idle down about 50 RPM below your programmed idle speed. If it dies or drops more than 50-75 RPM the throttle is closed too far. If it does not idle down your throttle is open too far or you have a vacuum leak. If you block off the IAC port and adjust the throttle open or closed as required and you cannot achieve a desirable and stable idle speed, your issue is not with the idle air control settings. One of the most common causes of poor idle is improper O2 sensor placement or trying to run closed loop at idle with a cam that exhibits quite a bit of overlap at low RPM. Both of these are easily corrected. Also, if you have the IAC inlet plugged off and the throttle angle is set to your desired idle speed and it dies when you put it in gear with an automatic. Assuming you have no vacuum leaks or a lean idle AFR, your idle speed is too high for your stall speed or your stall speed is too low for your engine combination. Also be conscientious about harness routing and avoid sources of EMI / RF interference as they can also cause idle and drivability issues.

#8 Hard Starting and Hot Restart Issues

Make sure the fuel pump is properly mounted and picking up fuel. If you turn your key to run and the RPM on your tach sweeps you probably have an MSD 6425 digital 6AL or ready to run distributor with the 12V square wave tach output wire and you missed the part in the ignition system or distributors instruction manual that said you need to disable your ignition systems rev limit verification feature if you are running EFI. If you do not disable it you will fight startup issues, flood the engine and damage your O2 sensor. Also check your cranking voltage if it starts hard. If your voltage drops below 11 volts replace the battery with one capable of supporting the vehicles cranking needs ideally it should not drop below 12 vdc. Digital electronics like clean stable voltage. If you're getting in the 10's your asking for issues.

#9 Incorrect Ignition Switch Wiring

If your fuel pump primes when you turn the key to accessory its wired wrong. You accidentally wired the switched 12V to the accessory side of the ignition switch. This circuit shuts off during crank and will obviously cause problems. Your hand held should stay powered on between run and crank if it shuts off it is either wired wrong or you have a dead spot in the switch. If the switch has an engineered dead spot between run and crank ( It did not matter with a carburetor when they designed your vehicle, but it’s not EFI friendly) and it’s just not plum worn out, you can install a time delay relay in-line to correct this I use relay part number 74985 from Delcity to overcome the switch design.

#10 Weird Sounds

Clicking, ticking and sucking sounds. Many of these are completely normal with EFI. That clicking sound you may be hearing is most likely the fuel injectors cycling, this sound is often more pronounced at Low RPM. Part throttle sucking sounds. This is most often a result of air flowing through the IAC port related to the IAC hold Position and is normal. Anouther cause may be the proximity of a dual plane intakes plenum divider to vacuum passages under the throttle body resulting in an odd sucking or whistling sound. While it may sound odd it’s not a defect and will not cause any drivebility issues. Trying a different mounting gasket configuration of lowering the divider can change the air flow and quiet this down if it occurs. This happens with some carburetors on dual planes as well. Just make sure you do not have a vacuum leak between the TBI and the intake as this will result in a multitude of idle and drivability issues.

Click here to read more articles about the Sniper EFI System!

44 Comment(s)

Todd:
10/22/17, 10:37:43 AM
Reply

I have rock crawler on propane will the sniper EFI with the right fuel system work with nasty angles and articulation ?

Would appreciate your input.

Chris Myer:
10/23/17, 05:31:15 PM

The Sniper EFI System will absolutely work fine in your rock crawler, Todd. The challenge will be what you call the "right fuel system".

Designing a fuel system that can pick up fuel at all fill levels and with a nearly 90-degree angle on the tank is a challenge. Fortunately, Holley has another product that can solve that: Hydramat.. Hydramat is not inexpensive but you won't believe what it can do. Be sure to watch the video embedded at the link above. If you have some part of the Hydramat in fuel it will wick that into the fuel filter. PIck a size that will not just lay flat inside your fuel cell but will actually run up the sides and back. Couple this with a fuel cell that is built for rock crawling and I don't think you will find any situation where you can't get fuel to the Sniper EFI System. From there it is a slam dunk. :-)

Gary Stopera:
02/11/18, 12:45:47 PM
Reply

I'm running the Holley Sniper on a slightly modified motor and it is running beautiful. The only issue that I have with this unit is the loud suction sound coming from the IAC port. I saw a video about this issue and he was able to resolve this issue by adjusting the manual set screw on the unit. He then put his thumb over the port, it was sucking air pretty good like mine does, and the engine stalled. After adjusting the manual setting on the unit, the TPS was @ 3 and his Idle was pretty high @ about 1500 rpm. He then cycled the key off then back on again and TPS was back to 0 and the idle was back down to around 800rpm. Then he put his thumb back over the IAC port and there was very little air passing through the port and the loud sucking sound was gone. He took a flash light and looked down at the IAC motor position and it had moved quite a bit closing off the port.

Now I had to try this and of course my results were not so lucky. I still have the lound sucking air sound. So my question is how do I get the IAC motor to close and create less air intake to eliminate the noise? Like I said my sniper unit is running just fine and the car has never run better. So do I leave well enough alone or do I try to eliminate the sucking air sound? Any help with this would be greatly appreciated.Gary

Chris Myer:
02/12/18, 01:27:54 PM

Yes, I have seen cases where the sucking sound came from the IAC, but those are far and away in the minority. Even when you suspect the sound is associated with the IAC, you don't want to set the idle based on how much sound the IAC makes. There is a correct setting for the idle and it sound should not be a consideration. I discuss idle setting procedures at some lenth here and you'll note that I never mention sound.

Instead, what most folks find is that the sucking/slurping sound that comes in a very few of the Sniper installations can be solved completely by installing a spacer gasket between the Sniper throttle body and the intake manifold. 4-hole spacers seem to work better than open spacers.

This Mr. Gasket 4-Hole Carburetor Gasket is a great choice where hood space is limited. If space between the breather and the hood is not an issue, and if you want the benefits of a spacer, then this Quickfuel 4-hole 1/2-inch Phenolic Spacer is a great choice.

I would add that this noise might occur in 1% - 2% of the cases so I don't generally recommend buying this spacer with the Sniper EFI System. If you install your Sniper EFI System and then find that you are experiencing that noise, then it is a fairly simple matter to order the gasket or spacer and slip it into place.

Gary Stopera:
02/13/18, 09:29:21 AM

Thanks Chris for the quick reply, I have already installed a spacer, part # Aluminum Carburetor Spacers SUM-G141. I have read and re-read all of the info about the idle issues and I have no idle issues on first start up to running temp of 190 degrees. My car idles beautifully @ about 800rpm. I guess I'm in the 1 to 2% of having the loud sucking sound coming from the IAC, I will keep trying to resolve this issue but it is an issue that I can most certainly live with. Much appreciated! Gary

Jeff Brown:
03/19/18, 12:46:54 PM
Reply

Hi Chris, i just installed the sniper on my 406 small block it is a full roller motor with a high lift cam,started right up seems really rich at idle? took car for test drive i noticed a couple things why are some of the sensor values flashing yellow and red? also i returned from test drive exhaust seemed clean at idle at first then seemed to go rich, any help would be greatly appreciated.

Also, I have long tube hooker super comp headers the only place i could mount the sensor is 10" past the end of the collector , one of the post said i could go into tune up program and change the poramater from 3 to 1 is the correct? seems to be running rich at a idle.

Chris Myer:
03/20/18, 06:51:44 PM

First, don't get too worked up about the flashing yellow and red values. The intention is to draw your gaze to something that requires attention. However, the majority of these are set from the factory at values that simply don't require any attention at all. All of these values are configurable. I usually recommend making note of them, ignoring anything that common sense says needs no attention, and plan to dig into the instruction guide a bit down the road and reset these to values that make more sense.

Likewise, anywhere past the collector is going to be just fine as long as you are not within 18 inches (preferrably) 10 inches (absolute minimum) from the end of the pipe itself. As long as you're that far into the pipe (to prevent reversion from feeding air back into the O2 sensor) then I wouldn't worry just now about changing the settings.

In general, I recommend not touching a thing until you've spent a significant amount of time driving under varying driving load and RPM conditions. First, there is the obvious--the system has to learn. But never ever forget there is a second learning going on--your own. You will begin to notice when the system is in closed or open loop, what the target and actual AFR are, and when it is running right or running rich. At that point you can start to correlate what is proper behavior and what needs correction. And the less correction you do until you understand that---the better! :-)

Joe Brown:
04/4/18, 11:44:30 AM
Reply

Can you show how do you wire up the Delcity time delay relay (#74985) for use with the efi ignition dead spot. You mentioned its use in # 9 of the top 10 Sniper EFI installation tips. Thanks

Chris Myer:
04/4/18, 11:45:41 AM

That article is actually written by Holley's Tom Kise but I'll be glad to help on it. The Del City Time Delay Relay is pinned just like a normal relay. So here's how I'd do it:

Pin 86: To your ignition switch (12 volts)
Pin 85: To Ground
Pin 30: To Battery
Pin 87: To Sniper 12-Volt Switched (Pink Wire)

When the ignition key is switched to "on" then power will flow between pins 86 and 85, closing the switch between pins 30 and 87. This, in turn, will power the Sniper. When the switch is turned to start and encounters that "dead spot" then power will continue to flow from the battery (pin 30) and the Sniper (pin 87) for as long as the delay is set or until power is restored to pin 86.

Roy:
05/25/18, 05:39:39 PM
Reply

Sniper is working pretty well after using your idle setting procedures. Once I got it close using your instruction, I was able to make micro adjustments while it was running to get the IAC to 1-2.

One thing I miss is the instant drop in rpms that my 650DP had. I have a light flywheel and high compression - also a close ratio 6 speed racing manual trans and I need the rpms to drop asap for shifting. Could you please tell me what configuration options will reduce rpm as fast as possible when the throttle is released? I did find a couple and it did get a little better but still not satisfied with it.

What is the ISC hold position for and why is it set @ 30? Can I lower it for this purpose?

Chris Myer:
06/2/18, 04:42:00 PM

You are on the right track!

Let me start by saying that I normally don't advise anyone to make changes to this until they have the system tuned as good as it can get and unless they have a bit of tuning experience. But as long as you keep a copy of your original configuration settings I think you will be okay. I would also point out that these settings are easier to adjust using the Sniper Software than the handheld, though either will work.

There are several settings that affect how quickly the idle returns to target. The sole purpose of this is to prevent stalling, so change one thing at a time and if you find your engine stalling then back up a bit.

The four key settings:

1.) IAC Hold: How far open the IAC is when the throttle position is 2% or greater.

2.) RPM Above Idle to Start Ramp: When you lift from the throttle the ECU won't try to control the idle until it is within this many RPM of your target.

3.) Ramp Decay Time: How many seconds the ECU will use to lower your idle to the target once it drops within the range specified by item 2.).

4.) RPM Above Idle to Re-Enable Idle Control.

You could simply drop 2.) to the same number as 4.) and set 3.) to zero, but I think you'll find that you will stall. So try cutting both of those numbers in half and see what happens. If that works then try halving them again. Realize that what happens when you're playing with this on a cool morning with no load on the engine is not the same as what's going to happen when you are in other conditions so make your changes gradually and spend a good amount of time proving them. Let me know what works for you! :-)

Greg:
09/9/18, 01:49:27 PM
Reply

I am in the middle of plumbing my new sniper throttle body system. That is pretty straight forward. It is going on a 1966 coronet with 1964 413 wedge. 10.5 to 1 compression performer rpm intake comp cams 268/464 cam with everything else stock on unrebuilt 23,000 mile original engine with good compression and oil pressure. Ran well on carb and electronic ignition. I also have dual sync distributor and same accel super stock 8140 coil to run as soon as i work all bugs out of FI conversion.

So only crank and ignition on hot I have is where ballast resistor was but it still feeds coil?

Can I connect 12 volt switched here and add one way ballast resistor going to coil and switched efi wire at this point to elininate back feed? If I go to ignition switch it is the same wire just 2’ away.

Does it matter if O2 sensor goes in driver’s side with true duals?

Thanks for spending your time helping us weekend mechanics. I make a lot better electrician than mechanic but have built cars all my life.

Chris Myer:
09/11/18, 06:30:33 PM

I would add a 12v-switched relay to power your Sniper. Run the switched 12-volt back as close to the ignition as possible. I know it's only 2 feet but ever inch counts. Then draw the power for the relay directly from the battery. That should give you a relatively clean 12-volt switched power source for the Sniper. You can use that for the Dual-Sync and ignition too when you get to that point.

Running the O2 sensor on a single side of the dual exhaust works fine. Stay after it--you'll make it happen!

Greg:
11/8/18, 02:28:52 PM

Thanks for your help system is working great!

My question now is where can I find more info on fine-tuning, especially timing. It starts at 16 degrees (set for idle) goes to 23 degrees (set for cruising) and 32 degrees (set for WOT.) More or less how do I build a timing curve?

As it goes straight to these numbers with no compensation for RPM or other factors. Can I get ready made tunes?

Even with this problem it is by far the best fuel system I have owned

Chris Myer:
11/9/18, 05:57:59 PM

I'm glad that worked for you! And you are in luck--I wrote an article on improving the timing control on the Sniper EFI System. You can find that here. Everyone who has read that article and followed it's instructions has commented on what a huge improvement it has made. Enjoy!

David Mercieca:
10/15/18, 03:06:06 AM
Reply

I have just finished installing my Holley Sniper to my 67 Camaro. I have a aeromotive stealth 340 fuel tank. My fuel pump keeps running when the ignition is on but the motor is not. What do I need to do to rectify this issue? The fuel pump should turn off after 5 seconds until the motor is started. My car is going on the dyno for final tuning next week. Would love some feedback as what I need to do to help my issue. Thanks

Chris Myer:
10/15/18, 12:47:04 PM

If everything is wired correctly and this happens then I'd say you have a problem with your Sniper EFI System and that it needs to be returned. But I strongly suspect that is not the case.

I am guessing you have some sort of current loop going on. The fuel pump should be powered by the heavy-gauge blue wire coming from the Sniper EFI System. There should be no relay added to this wire. Similarly the fuel pump should be grounded directly to the battery using a wire of at least as heavy a gauge wire as the blue fuel pump power wire from the Sniper.

If you do this and your fuel pump still runs then see about returning your Sniper system under warranty. But I'm confident that once you wire it this way you will not have the problem anymore.

David Mercieca:
10/16/18, 05:09:38 AM

Hi Chris,Thank you so much for your quick response to my query. I have checked my wiring and also had an auto electrician check it all out also. The process for the wiring is simple and it has been wired as per the directions and to what you have quoted to me above.In order for me to return the Sniper, what would the process be? Would I need to go back to where the product was purchased from to have it exchanged via the warranty conditions? Your advice would be appreciated. Thanks

Chris Myer:
10/17/18, 05:59:12 PM

Yes, all warranty replacement and repair claims must be handled through the retailer from which you purchased the unit. Good luck!

Pete Sanca:
10/22/18, 08:57:00 PM
Reply

Looking at the 4500 sniper and I run Super Street 10.90. I want to run an under the carb type throttle stop. How will this setup work? Engine is a BBC 533” and makes just about 800HP. Power glide with 1.80 first gear, 6,200 converter. 4.56 rear gear and total weight is 2825 with me. I really want to go EFI this year. Only thing I’m really looking for is an AFR of 14.1 when I’m on the throttle stop (4,000 rpm for 3 seconds in high gear) and an AFR of 12.8 to 13.0 everywhere else.

Chris Myer:
11/5/18, 06:33:43 PM

Unfortunately, I know NOTHING about throttle stops. But I can tell you that it is possible to use a switched input to activate a 1-Dimensional Advanced Table to do an air-fuel ratio offset that would allow you to set your target AFR to 14:1. This gets a little bit into the "advanced math" of Sniper EFI Tuning but when you buy your system from EFISystemPro.Com you can give me a call and I'll gladly walk you through this. In a nutshell, you do the following:

1. Activate Advanced Tables
2. Enable a 1D table
3. Set the table type to Air/Fuel Ratio Offset
4. Set the X Axis to RPM
5. Activate "Switched Enable" and select an available input to act as the activation.

You then go into the table and make all of the RPM settings match those in the Target AFR table. Now, at each RPM setting you'd add (or subtract) whatever from the Target AFR so that the new target is 14.0:1. Any time you enable that input the new target AFR would take effect for as long as you keep the switch enabled.

Louis Belloisy:
12/13/18, 07:00:37 PM
Reply

Hi, I have a 1987 Firebird with 305 engine and Quadrajet carb. I plan on converting to efi this coming spring. I have been looking at all efi units and I keep coming back to the Sniper. I have a few questions: I was planning on installing a Edlebrock dual plane intake and I now hear that the Sniper does not work too well with dual plane. Your thoughts?

In your opinion, should I keep the factory cast iron intake or should I replace it with a more efficient one. The car is 31 years old with only 13 500 miles on it. I really would like to replace the intake gaskets. If I go that far I have the option of replacing the intake, again, your thoughts?

Chris Myer:
12/14/18, 08:33:25 AM

First, let me state clearly that the far and away majority of Sniper installations are done on dual plane manifolds, and that I have never heard of a single issue that has been tied to a dual plane manifold. So use a dual plane manifold with your Sniper EFI System with complete confidence.

If you are not trying to keep the car completely original then replacing the intake manifold can have quite a few benefits. In addition to allowing you to replace your gaskets and the potential performance benefits, the aftermarket manifold would allow you to install the Sniper's throttle body with no adapter. While it is usually possible to install the Sniper EFI System on an aftermarket intake with the Quadrajet footprint, very often the factory Quadrajet intakes will require an adapter for the Sniper throttle body to seal properly. By going with an aftermarket manifold you avoid that issue entirely.

Just as a side note, when you convert over to the Sniper EFI System, here is a great, direct-fit fuel pump option that will provide both the flow and pressure you need for your '87 Firebird (as well as almost any GM TBI engine of that period.)

Louis Belloisy:
12/31/18, 02:02:13 PM
Reply

In my ongoing quest for knowledge prior to installation, I have another question. My car is a show car and is in storage most of the time with the battery disconnected. Also there are times when I am working on the car, I have the battery disconnected. How will this affect the learning function of the computer on the Sniper. Does this mean it will have to learn all over again? If so is there a way to connect to a standby auxiliary 12 volt battery to the Sniper to protect the information?Many thanks,Louis

Chris Myer:
01/2/19, 07:14:23 PM

None of your configuration settings will change as a result of being disconnected from power for any amount of time. Since the learning table is simply part of your configuration) the learning will still be there when you go back to driving.

Glenn:
02/19/19, 07:46:53 PM
Reply

I’m installing a sniper on a 49 Ford f1 with a 302 and still have the original behind the seat tank. Will the height of the return line be an issue?

Chris Myer:
03/4/19, 02:21:51 PM

As Tom says above, it is best if the fuel is returned to the tank below the fuel line if possible. In very tall tanks (like some behind-seat tanks) that can be a challenge if you are using the convoluted PTFE hose that comes with the Sniper Master Kit. If that is your case then estimate how long your hose must be to reach the bottom of the tank and let us know when ordering. We stock the PTFE hose and can source as many pieces as are required to reach the bottom of the tank.

Patrick Nadon:
02/20/19, 06:12:28 PM
Reply

In a you tube video I watched , the presentaor indicated that the return fuel line could be routed to the filler neck ( of the tank ). He gave no details, is this an option and how would one go about this

Chris Myer:
03/4/19, 02:25:14 PM

Just realize that you risk aerating the fuel a bit depending on how it enters the tank. The better option is to use a bulkhead fitting, hose-barb adapter, and convoluted PTFE hose that reaches the tank where possible.

Robert Russell:
03/26/19, 12:21:49 PM
Reply

O2 Sensor Mounting: The O2 needs to be mounted 6-8” after the merge in the header collector.Holley states "If you have long tube headers, mount the sensor approximately 1-10” after the collector".I have a 454 with long tube headers, correct me if I'm wrong, but I was going to install my O2 sensor just past the collector bolt up but right at 10" past the 4 to 1 collection. Do you see an issue with this? 6-8" would require me to install in my headers.

Chris Myer:
03/29/19, 12:16:04 PM

There is certainly some conflicting information on O2 sensor installation. Don't let that get the best of you. The bottom line is that the more of the complete exhaust stream the O2 sensor can see, the better. Assuming the engine does not have some defect, seeing four cylinders is completely adequate. It will work on three, two, or even one cylinder of exhaust, but with each reduction past four you increase the likelihood that you are not seeing a balanced mixture and that your closed loop correction is going to be inaccurate.

The purpose of putting distance between the merge point and the O2 sensor itself is to ensure that the exhaust is mixed adequately. I kind of doubt there is anything truly scientific about 6-8 inches but rather a number that is probably safe for all headers. But as you go farther back, it only gets better. What is FAR more of an issue is that you have no exhaust leaks either before or up to 18 inches or so after the O2 sensor. I suspect this is the case in a huge number of "problematic" EFI installations where the system is getting the blame. There is really no room for error on this.

Greg Pyle:
03/28/19, 02:49:20 PM
Reply

Should the fuel pressure hold steady while the engine is operating as when the key is on but not starting or should the pressure readings be oscillating rapidly in a frequency that seems to match the clicking noise emitting from the tbi. Pressure holds steady at approximately 50 psig when engine is off.

Chris Myer:
03/29/19, 12:52:12 PM

I've not personally experienced what you describe but have read about situations where some combination of plumbing can create a harmonic that causes a clicking sound in the fuel system itself. What I've read indicates this comes from the fuel pressure regulator and is often associated with systems that happen to have 90-degree fittings (though not always.) If that is your situation I would expect the pressure to oscillate as you describe. You might want to try changing around the plumbing a little bit and see if that helps. Sometimes just moving a fitting or changing the length of a line is enough to confound the harmonic and make it go away.

Jeff Rauscher:
04/3/19, 06:48:59 PM
Reply

I am having a 2 572 BBC being built for my boat. I have purchased two sniper EFI with the MSD distributor kit. I am running a wet exhaust with O2 sensor plates. I have two questions at this time: 1. Does the sniper kit support dual O2 sensors? 2. How do you set this up?Thanks!

Chris Myer:
04/4/19, 05:55:56 PM

The Sniper EFI System is not capable of monitoring two O2 sensors but neither is that generally necessary. Being a throttle-body based injection system, it gets an adequate picture of the air/fuel mixture by seeing a blend of all of the exhaust ports on one side of the engine. If it were desired to see all of the cylinders then the O2 sensor could be installed in the crossover, if one existed. Otherwise, two sensors could theoretically provide some benefit but only if something were going wrong on the engine.

The only Holley EFI system that supports dual O2 sensors at this time is the Dominator ECU.

Tanner Dennis Conley:
05/29/19, 11:26:15 PM, Holley
Reply

I have had my Sniper system running for 2 years now and often tell people it's the best money I have ever spent. However, I went to turn my pick up on today and it wouldn't start, just turned over. Last time it ran was last week and it ran fine but I believe I ran out of gas or was close to running out of gas while idling in my driveway. Any suggestions? Only thing I have done since last Wednesday was add Holley EFI gauges. Nothing else (except gas)

Chris Myer:
06/13/19, 03:36:28 PM

In a no-start situation my direction is always the same. Look first at the tachometer on the Sniper handheld. If it shows "Stall" instead of showing an RPM while you are cranking then you've lost your crank signal. Fix that.

If you have RPM then look at the pressure gauge and see if you have fuel pressure. You do have a fuel pressure gauge, right? If not then stop and buy one now. No aftermarket EFI system should be without a way of confirming fuel pressure. If you don't show any fuel pressure then fix that. If the fuel pressure is a little low don't worry about that. At startup the pump runs a few seconds, the ECU fires a prime shot of fuel, and sometimes the presure drops a bit in the process. It will come back up when the engine is running.

If you have fuel pressure then you've got to dig deeper. Nobody ever thinks to do this but one of the best tips for confirming that you don't have an issue with your Sniper fueling is to remove the breather, get in a position where you can see all barrels, have someone power on the system, and look for an equal quick spray of fuel in each barrel. Is a tremendous volume of fuel sprayed in all barrels? Disable the tach sweep on your ignition box. Is a tremendous volume of fuel sprayed into just one barrel? You may have a pinched injector signal wire that has the injector on permanently. Is one barrel not spraying at all? You may have an injector connector that has come loose.

A final note that I can't emphasize enough. Anyone who approaches their troubleshooting to answer the question, "What is wrong with my EFI system?" is setting themselves up for unnecessary frustration. It is an internal combustion engine. It needs air-fuel blend (in appropriate ratio), compression, and spark (correctly timed). Figure out what it's not getting and the find out why. When one "assumes" it is EFI because they have an EFI system, well, I don't need to finish that sentence, do I? :-D

Don Murray:
07/28/19, 01:38:16 AM
Reply

Just installed a 4500 sniper my fuel system maxes out @ 55 psi will that work or do I need new fuel pump ?

Chris Myer:
08/2/19, 03:45:04 PM

You need a new fuel pump. But let me elaborate a bit. The problem isn't the 55 PSI. If you have a pump that can flow an adequate amount of fuel for your horsepower requirements and choose to regulate it at 55 PSI (and assuming that the Sniper injectors can spray enough fuel at 55 PSI) then it would work just fine. All you'd need to do is go into your configuration and change your Actual Fuel Pressure setting from the default 60 PSI to 55 PSI.

But I suspect that's not the case here. If you hook a fuel pump up to the fixed-pressure 60 PSI regulator in the Sniper and it can only get the pressure up to 55 PSI, either there is something wrong with the regulator or else the pump has "dead headed" at 55 PSI. That means at or above 55 PSI it is capable of flowing ZERO fuel. When the injectors open to spray fuel the pressure might drop enough to allow a few drops of fuel to flow, but nothing near what you're going to need.

Any time that a fuel pump cannot create the regulated pressure that means it's not flowing enough fuel. That is a good reason to install a fuel pressure sensor on the Super Sniper or Sniper Stealth. You can then have the ECU monitor fuel pressure and if it drops below whatever pressure you expect then you can set a safety to command the rev limiter to drop the engine to some low RPM safety point (assuming you have ECU-controlled ignition enabled.)

Robert Weston:
07/31/19, 10:42:00 AM
Reply

I have the sniper efi system with the holley retro-fit in tank electric fuel pump. Do I still need the holley 12-753 30 amp relay

Chris Myer:
08/2/19, 04:29:13 PM

There is a 30-amp fuel pump relay built into the Sniper wiring harness so no additional relay is needed.

Greg Schwarzer:
05/29/20, 11:13:09 PM

Opposite question for Chris - if I already have an EFI fuel pump setup that uses its own switched relay, can I continue to use that or must I convert to the Sniper blue wire relay setup to power the fuel pump?

Chris Myer:
06/25/20, 09:43:06 AM

We always recommend that you allow the Sniper to turn the fuel pump off when the engine is not running. This is most easily done using the blue fuel pump wire. Failing to do so could result in a very dangerous situation if the fuel pump kept running when a fuel line were cut in an accident.

Doug Welch:
08/16/19, 10:54:32 AM
Reply

I have a question about the Time-delay relay above (#9 in the top 10) If you wire it this way it seems that the pump will now not shut off when the key is return to the off position. At least not right away (after time-delay set in relay). Is that an expectable by-product of adding this relay? Maybe I am missing something here.

Chris Myer:
09/11/19, 04:36:41 PM

Good point. Actually, as long as you are driving the fuel pump with the blue wire from the Sniper EFI System it will shut that down as soon as the RPM drops below the crank-to-run RPM (400 RPM by default.) Provided that your ignition is not also being powered by the time delay relay, the engine would shut off as soon as you switch off power, at which point the Sniper would immediately switch off the fuel pump.

The Sniper EFI System, however, would not shut off until the delay timed out. Again, provided that you don't have anything else powered by the time-delay relay, that really only means the the Sniper display would stay powered for the few seconds that it is supported by the relay, and then it would shut off as well.

Robert Weston:
09/5/19, 01:09:38 PM
Reply

Is the Sniper EFI system rev-limiter capable

Chris Myer:
09/5/19, 05:32:43 PM

Sure. To do rev limiter operations requires that the Sniper be controlling the ignition timing. For this I recommend the HyperSpark Distributor.

Joe salamone:
01/20/20, 10:32:59 AM
Reply

#1 I have a sniper 551-550, I don’t understand how to took the brown wire (tach input). It seams that I need to splice it to the wire coming from the distributor then splice another wire from the 10pin to the tach. #2 I have a return 1/4” pipe coming out of the fuel pump at the fuel tank. Can I use this for the return.Thanks for the help, Joe

AJ:
01/22/20, 04:44:01 PM

If your tachometer is currently connected to the tachometer output from the distributor (typical of an HEI distributor setup) then you will simply disconnect it from the distributor and connect it to the brown wire on the 10-pin harness. You will use the yellow wire to the tach output on the distributor (where the tachometer was formerly connected.) Never use the yellow wire if you're running a CD box like an MSD 6.The 1/4-inch line should not be used as a return. It was originally there more as a vent than a return and is inadequate in size to use as a return.

Dale Cotton:
04/13/20, 09:48:57 PM
Reply

This site is very informative. Cheers

Ruben Valle:
04/17/20, 07:07:25 PM
Reply

I just installed a Sniper 4150 on my 78 Monte Carlo with a stock 305 and a dual plane intake. It fired up, seemed to be learning and then POOF...puff out of carb and wouldn't restart. To be 100% honest I was having an issue prior and flooded it. I am letting it set over night, cleaned plugs as well. I checked fuel lines to make sure I didn't reverse them. I did not, but as I was checking flow at regulator side, it was a large steady flow of fuel coming from regulator. Is this normal? I figured it would be minimal. Granted, car was not on but still seemed like a lot of fuel to be returning.

Chris Myer:
06/3/20, 05:30:09 PM

Yes, there should be a steady flow of fuel out of the return. But you don't mention fuel pressure at the inlet. You're not running your EFI system without a gauge are you? Get a gauge. Don't be that guy. :-)

Bill Fabian:
05/15/20, 04:16:14 PM
Reply

I’m getting ready to instal a sniper master kit on a Ford FE 390 that currently has a Pertronix distributor with the Ignitor 2 module. I’m not looking for timing control just upgrade to EFI. Is the sniper compatible with my distributor?

Chris Myer:
06/25/20, 09:47:49 AM

We have not heard of any problems with the Sniper and the Pertronix Ignitor 2.

Deke:
06/18/20, 09:05:51 AM
Reply

I've been running the super sniper 1250 on my 6.2 ls for several months now and am still fighting cranking issues. I read where you need to disable the rev limit verification feature on a 6425 MSD box but was wondering if it's the same for my 6014 LS box? Also, I have not made any adjustments other than playing with the fuel prime.

Chris Myer:
07/2/20, 04:56:54 PM

In my experience startup fuel tends to be too much. Try cranking immediately upon key-on--before it has a chance to prime. If it cranks better then you know you're getting too much fuel. Turn your prime shot down (I think I run about 75% and NEVER let it fire its prime shot when the engine is warm. Beyond that you can turn your cranking fuel down. This is a bit tricky. You just have to go one direction and see if things improve or not. Go Gators.

Dawson:
06/21/20, 12:17:42 AM
Reply

My setup requires too much pedal pressure both starting and running. It appears to be in throttle body? Whats the fix?

Chris Myer:
07/2/20, 04:53:03 PM

We offer two potential solutions. A throttle linkage extender and a progressive linkage kit. Have a look at those.

Damon B:
08/11/20, 07:21:51 PM
Reply

Hello, I just finished installing a Sniper stealth 4150 with an external pump supplied with the kit. All seemed well with the setup and going through the handheld. i can hear the pump, but nothing is coming through the fuel line. I have it disconnected to flush any debris out.Thank you

Chris Myer:
09/29/20, 12:50:49 PM

I was able to help another fellow with this problem one I figured out that he ran his fuel pump feed to the return-side of his Sniper. That's not the case here is it? And I've helped my share of folks with fuel pumps in empty gas tanks. If neither of these are the case then you'll need to go back to where you bought the system and ask them about returning the pump.

Greg Baker:
08/22/20, 12:42:08 PM
Reply

Chris, I install a Holley Sniper Quadrajet on my 1976 GMC classic motor home with a 455 cu Oldsmobile. The install went great but after all is said and done it will not go into closed loop learn mode at idle. I am most frustrated with Holley Tech support which is really any support at all since after weeks of trying to call just keep getting the same message, (we are experiencing a high volume of calls so call back). I was wondering if you could help out? Thanks in advance.

Chris Myer:
09/29/20, 12:49:19 PM

Start by increasing your TPS and MAP ROC blanking values. I bet this fixes your problem. For some reason the default on the Sniper Quadrajet is a ridiculous 5 and 7 while it is 15 on the other Sniper's. Unfortunately, the only way to do this is with the Sniper Software. Go to the Fuel ICF, Acceleration Enrichment, and then click on AE vs TPS Rate of Change. At the bottom you'll see AE vs TPS RoC Blanking. Increase that to 15 to start. Then, click on AE vs MAP Rate of Change and change that to 15 as well. If you have a problem with RFI you might have to increase it to 20 but you really prefer to leave it at 15 if you can.

Darren McCarthy:
09/1/20, 07:28:01 AM
Reply

Hello Chris. I need to get an answer to the question concerning the TPS. Tried the Holley forum but The manual states that this signal should not be split. Therefore what remote TPS can be used? There must be an option that has been found to work. Your assistance would be greatly appreciated. Cheers Darren

Chris Myer:
09/29/20, 12:48:37 PM

Hard to answer. Do as I Holley says? Or do as I do? Confession: My TPS is split and works well. But I have never heard of anyone else who has had success doing this. So I can't tell you what TPS to use. Nor can I really recommend that you split it as I have. Good luck!

Joe:
09/10/20, 01:19:42 PM
Reply

what is the proper air/fuel ratio for a sniper on a ford fe 352? It seems to be going threw gas faster then it should.

Chris Myer:
10/6/20, 05:01:24 PM

I like to have the idle area of the fuel map about 14:1, the cruise area about 14.5:1 and the WOT area about 13:1. Basically lean everything out by .5 and it should help a lot. Idle and cruise can be tuned leaner with "seat of the pants" feel. It's almost impossible to hurt an engine with no load on it. Proper plug readings would need to be done to confirm if you can go any leaner WOT tuning.

Suren Maharaj:
10/5/20, 02:47:25 PM
Reply

I see recommended plugs are resistor type. But I have MSD 6 AL. MSD recommends non resistor plugs. Can I get clarity please?

Chris Myer:
10/8/20, 04:50:19 PM

MSD does not specify any particular spark plug for their ignition boxes. You can run resistor or non resistor plugs with the 6AL box. For the Sniper it is best to run resistor plugs

corey smith:
10/21/20, 01:52:57 AM
Reply

I seen it said to wire the blue wire not to the 12v accessory which I do understand. I have a sniper 1250 with a msd 6014 and a painless rocker panel . I have the 12-1800 dual holley pump also. My question is if both of my fuel pumps are wired from relays to my rocker panel where does the blue fuel pump prime wire connect or would you just not use it altogether. Fyi both fuel pump rocker switches have momentary primes.

Chris Myer:
11/16/20, 06:14:29 PM

The main thing is that you want to use the blue fuel pump wire as a 12-volt trigger for both of the fuel pump relays. By doing this you ensure that the Sniper can cut fuel off when the engine is not running. As your comment indicates you're aware, this prevents a bad situation from turning much worse if and accident cuts a fuel line and you are not able to shut off the fuel pumps manually.

Michael Gardner:
11/26/20, 01:09:23 PM
Reply

Can I run the pink ignition wire to the coil positive? I can't find a good spot in the fuse block

Chris Myer:
12/1/20, 04:16:34 PM

I don't recommend this. It connects the Sniper switched power to a very "dirty" power source. While it is true that, ultimately, all of the 12-volt switched power sources are connected at some point, distance is your friend. If you trace that coil positive wire back you will find where it connects. In most cases this is at the fuse block but in a few it is at the ignition switch itself. Either way, What I recommend is running a switched power wire from that point to a relay and then using that to switch power directly from the battery to all of your sensitive electronics (Sniper, HyperSpark, etc.)

Craig Sproston:
12/6/20, 01:48:30 PM
Reply

Some good info here thank you. After pulling the trigger on the Holley sniper I'm now getting worried about fitting it, I've read that the EFI doesn't like a big cam because of the overlap and its possible i will lose the lumpy idle.

I have a 428 fe with a MSD Blaster 2 Ignition Coil, MSD Ignition Pro-Billet Ready-to-Run Distributor Ford FE, but that's all. I'm worried that the engine will stall at idle. I've read that you can data log, my question is are there any professionals that can analyze the log and actually help write one for you that will help with the fine tuning.

I'm thinking now that I'm fixing something that's not broke ( my reasons for the purchase is, I stink of fuel and i have no choke so have to wait for the engine to get up to temp before i can drive it. Am i doing the right thing?

Chris Myer:
12/8/20, 03:01:41 PM

Several things to cover here. First, it is fake news that EFI doesn't like big cams. EFI doesn't have feelings--it doesn't care what cam you use. :-) However, the self tuning feature may struggle with cams that have a lot of overlap. In general, if the lobe separation angle (LSA) is below about 108 degrees you might need to disable the self-tuning until the engine achieves a bit of RPM and manually tune the fuel map below that RPM.

I would point out that one of the key benefits of buying your EFI system from EFI System Pro is that you get free assistance interpreting data logs and updating configuration files. Help for our customers is just a phone call, test message, or email away. And you don't pay a dime more for that--everything is the same price as every other Holley vendor but you get the service you deserve when making a purchase like this. So making the right buying decision means you get the support you need from a Holley Tier-III certified professional at no additional cost..

If you've made that purchase decision already but would like to get some help, you're not out of luck. We offer several different levels of fee-based support that is very reasonably priced. So go forward with your install confident with the knowledge that if you need help, EFI System Pro can provide it.

Michael St Ours:
02/16/21, 12:34:48 PM
Reply

Chris, this is going to be an easy one. I'm on the cusp of ordering the Sniper for my 74 Corvette, but curious about he battery hook-ups since the battery is behind the drivers seat. Is there enough cable to get to the battery?

Chris Myer:
02/18/21, 02:43:17 PM

It is likely that the main power and ground leads are not long enough. But you can extend the leads using wires of an equal or heavier gauge. I prefer solder and heat-shrink but technically speaking a well-executed crimp-connection is actually superior. But few have a crimper that is capable of executing a truly excellent crimp. So you be the judge.

Victor Popper Jr:
03/2/21, 01:07:46 PM
Reply

I have a 88 f150 302 with factory efi and dual tanks. Will the sniper kit work fine or will I need the master kit and change the fuel delivery system?

Chris Myer:
03/2/21, 02:22:00 PM

Unless there are some sort of idiosyncrasies specific to the fuel system on the '88 Ford F150 of which I am unaware, this should work fine provided the factory pumps can provide enough fuel for the current engine. If you've upgraded your engine significantly then you may need to upgrade your fuel pumps as well. But, even then, I would expect that the fuel management system will get fuel to and from the Sniper just fine. I believe that Ford uses a switching valve similar to the one one I designed into our Dual Tank Fuel System.

Ralph Schubert:
04/1/21, 10:50:03 AM
Reply

Hey Chris, just finishing up my Sniper 41504BBL install with in tank pump / no return line from EFI needed...does the fuel line need to be bled up to the 4150?

Chris Myer:
04/1/21, 04:38:00 PM

Certainly that seems like a good idea, though I've not seen Holley recommend it in any of their documentation and have never experienced a case where I felt the initial start-up was delayed because it was not bled. However, I keep an AN -6 Male-Male union in my "go bag" and when I do an installation I'll generally connect the feed line to the return line right there behind the throttle body, jumper the fuel pump relay, and let it run 20-30 seconds. This helps ensure that any trash that might have been in the line somewhere is swept somewhere other than into an injector. Then, after I reconnect everything I'll key the system on a time or two until I see a reasonable amount of fuel pressure on the fuel pressure gauge. In most cases you just hit the key at that point and it's happy dance time.

Steve Frantz:
06/1/21, 07:20:13 PM
Reply

I tried the external inline pump while installing the 2300 in my 78 cj-5. Had issues so I’m now going with the Holley in tank pump. Question is, do I just plug what was the return at the throttle body? Thanks,

Chris Myer:
06/13/21, 03:19:18 PM

Exactly. Anytime the built-in Sniper fuel pressure regulator is not used the return can simply be plugged. Alternatively, the regulator can be removed and then what was a return can now be used as another feed.

Robert Shannon:
06/15/21, 02:20:39 PM
Reply

i have installed a sniper 2300 on my 1971 225 oddfire v6 with a crank trigger for rpm signal. The engine starts and idles great. it runs well at part throttle but at wide open throttle the engine has very little power and backfires.where do i go from here.

Chris Myer:
06/26/21, 10:41:42 AM

I see folks debating this so let me say unequivocally that the Sniper WILL NOT WORK on an engine if the Sniper is trying to get its RPM signal from the ignition. Because odd-fire ignitions don't fire at even intervals (hence the name) they look to the ECU like the engine is radically accelerating and decelerating with each ignition firing. It just can't work properly.

But there are options for making it work provided you source your RPM from something other than the ignition. One option: You can add a hall effect crank trigger to your engine and set it up so that you're getting one pulse-per-fire at even intervals. Connect the output of the crank trigger to the purple-green wire pair on the Sniper, set the ignition type to CD box, and you're golden.

Brett Arnott:
06/24/21, 11:10:14 AM
Reply

Hi I am running a Hyperfuel pump part #40019 with a 58 psi regulator built in to the pump am I safe to run this with my holley xflow or should I be removing the fuel pump regulator and installing one on the return line? The xflow instructions state it needs 60 psi. Thanks!

Chris Myer:
06/26/21, 10:29:55 AM

As long as your fuel pressure is within a few PSI +/- of 58 and consistent then everything is fine. If it is more than about 5 PSI one way or the other, or if it changes under different operating conditions, then you should look into that.

Brett Arnott:
08/18/21, 10:47:22 AM
Reply

Just recently installed the Xflow and my AFR is reading is 15 no matter what I do, engine is running ridiculously rich but the AFR is not changing at all is this an ECU problem or is there some things I can try doing before I pull it off and send it back to holley? I Had a holley sniper on this car with no issues whatsover. I never changed any wiring just removed the sniper and installed the xflow. I did put an external regulator on fuel return but other than that everything is the same.

Chris Myer:
08/20/21, 11:42:41 AM

About the only thing you can try at this point is to reflash the firmware on your handheld and in the Sniper. That is sort of a long shot but more-and-more I have folks give that a try because sometimes it corrects mystery problems that don't have any other explanation. (Plus, it's easy to do---see this article.) Beyond that you're going to have to get Holley tech support involved.

Todd Gillies:
12/4/21, 08:40:56 PM
Reply

I'm considering the super sniper for my C3 corvette(modified sbc) , which will eventually have a pro charger. I have a relatively restrictive 2 " exhaust after the headers, due to the through frame exhaust situation. Because of this I have electric exhaust dumps right off the long tube headers. There are just turn downs after the electric cut outs. Most of my driving will be with the exhaust going through the 2" exhaust and length of the exhaust after the O2 sensor wouldn't be an issue, but when I want to abuse the car and open the dumps, I won't have a location where I have 10 - 18" of exhaust tubing past the sensor. Any suggestions ? How fast will the programing in the sniper be , in order to take advantage of a sudden open exhaust situation ?

Chris Myer:
12/11/21, 01:34:50 PM

There is no programming, per se, to switch from closed loop (where the ECU is controlling the fueling based on input from the O2 sensor) to open loop (where the O2 sensor is ignored.) Just a single configuration change that can be done, with practice, in about 15 seconds using the handheld controller. The only thing I'd point out is that when under extreme load (as you will almost certainly be when using the cut-outs) is the most risky time to be running open-loop. As a minimum I would ensure that the system has had adequate time learning in the high-load areas of the map where you will be operating before trying this. Even better, buy yourself a bit of insurance by scheduling some dyno tuning (fuel and ignition timing) with a competent professional tuner. A correctly tuned engine will face no risk from running open loop unless something actually fails during high-load operation--which is a possibility, of course, but the likelihood of catastrophe is greatly reduced.

Fred McSkimming:
02/24/23, 11:46:54 AM
Reply

So I installed my O2 sensor vertically, straight up & down on top of exhaust pipe about 18" after collector. From what I read it should not be installed vertically? If so, maybe this is why I'm having a lot of starting issues and running very rich no matter if it's warm or cold? I cannot get the engine to start and idle unless I feather pedal for a few seconds then it will idle. I've gone through all the steps and cannot seem to solve the problem. Chevy 350, rocker cam, mild cam.

Chris Myer:
02/25/23, 03:41:27 PM

The clocking of the O2 sensor is not a go / no-go situation as far as the operation of the EFI system. Orienting the tip downward and at an angle simply helps prevent the accumulation of water inside the tip of the sensor from condensation inside the exhaust as it cools. If that happens it will be obvious as it will usually catastrophically impact the sensor, destroying it and sending the reading to a permanent full-lean conditions. If your O2 sensor is pegged lean, then replace it. If not, then the orientation of your O2 sensor is not your problem. Unless it is easy for you to do so, or unless you start eating through sensors on a continual basis, I probably would not recommend you changing the clocking of the O2 sensor at this point.

james orr:
09/7/23, 02:59:06 PM, efisystempro.com
Reply

Hi, new guy. 68 ford 200 i6 with new 550-552 sniper to take place of autolite 1100. New motor not broken in, wondering what tp do for initial run/break in of the motor, Is there a setting that the ECU needs to be put in ? Motor Needs to run between 1800-2200 for 30 ish minutes, Any special aettings I need to know about ?

Chris Myer:
09/9/23, 12:52:52 PM

There is nothing I'd do differently in the configuration for a break-in. The most important thing is that it be able to crank quickly and run on its own.

In general, most folks' experience with the Sniper is that it does just that. I call it the "Happy Dance" moment. You spend all this time carefully following the instructions, wondering if it will work. You run the setup wizard, hit the key, and it immediately cranks and runs. Happy Dance!

On any Sniper installation where it will control both fuel and ignition timing I ALWAYS recommend using the existing known-good distributor (if that is possible) rather than performing initial start-up with Sniper-controlled ignition timing. Even on an experienced motor I say first install the Sniper, get it running with the existing ignition, then add the ignition control after you have that working. No down side at all to this approach and if something doesn't work as expected you are only looking at fuel delivery.

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