Your shopping cart is empty!
Ok, we have enough Sniper systems out there that I thought it would be a good idea to create a posting on challenges that might arise during installation. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. Across the board, all of our customers say how impressed they were that it started and ran right out of the box just by following the simple installation instructions.
A few, however, get tangled up getting the idle control working just the way they want. We offer some tips to help with that.
(Note: in the original version of this post we had a section about checking the idle speed curve setting. This was an issue in the earliest version of the Sniper firmware. Since that has long been corrected we have moved that information to the bottom of the article.)
Let's start by not assuming anything. The Sniper Quick-Start Manual provides the following instructions for setting the idle. If you have somehow overlooked this, start here:
Holley Idle Speed Adjustment Instructions: Once the engine is up to operating temperature, the idle speed can be set to what was configured in the Wizard. To do this, open up the Initial Startup gauge screen that was used in section 17.0. With the vehicle in neutral, adjust the idle screw until the IAC Position reads between 2 and 10%. While adjusting the screw if the TPS position reads begins to read higher than 0% cycling the ignition switch will recalibrate the TPS back to zero.
NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160°F!
Tried that and it didn't work? Okay, try my method. Nothing against Holley's method but I need to keep things simple and I do that by eliminating the effect of the IAC entirely while getting the idle speed adjusted.
Note: The IAC breather hole is the roughly 1/4-inch triangular hole that sits above and between the secondaries.
Chris's Idle Speed Adjustment Instructions*:
*Note: If you are using your Sniper to control ignition timing then I recommend that before you start this process you disable idle spark control If you are trying to do this while the ECU is simultaneously trying to bring your idle under control by adjusting the advance it is going to be counter-productive. You can disable the idle spark control at the locations below. Be sure to re-enable it once you get your idle tuned.
Software: Idle > IAC Settings > Idle Spark
Handheld: Tuning > Advanced > Advanced Idle > Idle Spark
After completing this 10-step process, if the temperature displayed on the handheld is still above 160 degrees the engine should go right to it's target. The IAC should display a 2-8% to bring the idle up to the actual target. The throttle position should be zero. If you find that the IAC is more than 8 percent, repeat this process and instead of shooting for 50 RPM below your target make it only 40 RPM below the target idle speed. If you complete the process and find that the IAC is less than 2% at idle, repeat the process and use the set screw to make the RPM about 60 RPM below the target. It may take a few tries. It's called tuning. :-)
If you have performed the adjustments above and still have RPM issues, it's time to look for clues. Often, folks will say, "I did everything you said. Everything was working perfectly and I shut off the engine. Then, the next time I cranked it, the idle went high and won't come down!" When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC.
If your TPS has snuck up to 2% then your IAC will be at the hold position, which by default is 30%. When you open your IAC to 30% you are naturally going to have a high idle condition. What might cause the TPS to go to 2%? Generally, one of two things: a stuck throttle or noise on the TPS signal. Physially manipulating the linkage by hand will generally reveal if you have a sticking linkage that is preventing the TPS from returning from zero. The only way to confirm RFI problems is by doing a data log. If you do find you have RFI issues then I've written an <a href="/efi-pro-hangout/holley-sniper-efi-instruction/solving-sniper-rfi-problems/efi-pro-hangout/holley-sniper-efi-instruction/solving-sniper-rfi-problems">article on solving RFI problems</a>.
If your TPS is at zero and your IAC is at some random number above 8% (but not exactly 30%) then for some reason your engine has not met the conditions to ramp down to target idle. It is probably that your RPM above the maximum point at which ramp-down can occur. If you are idling at 2100 RPM (based on a default IAC Hold position of 30%) and your target idle speed is 900, then the ECU is not going to try to idle down. The solution is to either lower the IAC hold position or increase the RPM above idle to start ramp (default is 1000 RPM). You can find those settings here:
Handheld: Tuning > Advanced > Advanced Idle > Rampdown
Software: Idle > IAC Settings > IAC Ramp Down
However, whenever you start changing things, you can get into a chain reaction. If you set the RPM above idle to start ramp too high, then it may not ever get down to the RPM above idle to re-enable. Which means you either need to increase that number or increase the ramp decay time. I would suggest at that point you need to contact whoever is providing your tech support and find out why the default values are not working for you.
No, the idle speed curve setting isn't something that you normally worry about--and especially not down at minus 40 degrees farenheit. This curve runs fom -40 degrees to 260 degrees, and gradually reduces the RPM along that range. Or, at least, it should.
It turns out that some of the Snipers are shipping with the minus 40-degree setting drastically lower, as shown in the following image. So what--you're never going to drive in minus 40 degrees, right? Well, it turns out that with the current firmware this throws the IAC control into a bit of confusion. When this happens, it is impossible to convince the Sniper ECU to allow the RPM to drop below a set RPM--regardless of what the target idle speed setting is.
The fix? Simply use your handheld controller and go to the Tuning > Advanced > Advanced Idle > Idle Speed screen and click on the Idle Speed Curve function. The window you saw in the image above pops up. If the minus 40 degree setting is lower than the setting to the right, simply move it up so that it looks something like this:
The folks who have tried this have found that their idle speed control behaves much more as they expect. Some have suggested mis-setting sets the idle speed at 850 RPM but I suspect it is not a fixed number but rather a delta of about 300 RPM above the target. At any rate, once the setting was moved up, the RPM jumped right to the target RPM and was solved.
If you have an installation or start-up issue that is nagging you then please use the comments section to reply and we will gladly provide more information that we hope will be useful to you. Thanks so much for reading!
Did you find this enlightening? Then why don't you Get On The List for Emails Straight From Our Pro? In the time it takes to add your email address you can be at the top of the heap for getting the latest information from our authority. We're never going to fill up your email box with nonsense. These aren't generic newsletters either but instead personalized emails. Jump on board now!