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. I can drive it a bit but pops through the throttle body when pulling out from a stop (4 speed) and sometimes in the exhaust out on the road. Idle Tuning is a very important part of tuning any EFI system, especially our self-learning units like Sniper or Terminator X EFI. When I covered the IAC with my finger, the RPM dropped so low it stalled. I installed the Holley gauge you suggested in another thread at the fuel input to the TBI, and the fuel pressure is constant around 64 according to the gauge. Capability Range: Advanced and when I close the IAC's hole with his finger, the engine is normal.The data on the touch screen I see are:AFR, A / F = 35.6 I have changed my roc/tps to 7 from 15 but that only took me out of learn mode. I also noted that after some time, I could change those values as I saw fit. We have never had that problem with any of the units that we have shipped. The first 250-300 miles were amazing as the Sniper EFI worked flawlessly. In this short video you learn to replace the IAC. How can I adjust the startup speed down to about 1400 RPM? Unless you have ignition control enabled, that is the only thing it can do to reduce the idle.Realize the only things that can cause the car to idle up as you describe are air and ignition advance. Strangely, what I've seen is that it idles too lean as the injectors are effectively shut off.Thanks again for the follow-up and glad to hear that everything is working well now. Also when ac kicks on it will idle down and stall. It sounds a little different from mine, since it commands a 1300 or so increase intermittently. Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps. I am having an idle issue (other than that is absolutely perfect). 90% of problems, (INCLUDING MYSELF) could be answered/fixed by just reading the instructions. I put it in neutral and the idle RPM had increased to 2100-2200. If I block off the iac with tape , I can get it to somewhat idle, but its not consistent. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. Hi. NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160F! is jumping all over the place when you experience this condition, it does not Commanding the engine to automatically increase speed when switching into drive is a little scary to me though. Using a Snap-on variable timing light so this is why I say timing is perfect. When you open your IAC to 30% you are naturally going to have a high idle condition. That could be a problem with the TPS or it could be some sort of throttle linkage issue. Tps is saying 26% when it at idle. While it is not mandatory, I recommend the Sniper EFI CAN-to-USB Adapter to move the data between your Sniper EFI and your PC rather than trying to do this via the SD card. I've tried repeatedly re-creating the scenario in hopes that the E.C.M. No timing control, coil negative ignition type. If you haven't installed a The fact that it ran so (at times) with 90+ PSI fuel pressure is a testimony to the Holley's closed-loop technology. 63 bomb Second--even in the HP and Dominator systems where a fuel pressure sensor can be dalogged and displayed, the fuel pressure is not fed back into the algorithm. Give them a call and if they are unable to provide customer support the contact the Holley tech support line at 1-866-464-6553. Have you confirmed your fuel pressure at idle is 60 PSI? Thanks for the information you have provided on this site. In fact, it is those users who seem to end up most impressed with the system. But you've got to find where air is getting into your engine.The reason it's going up as high as 2400 RPM is because once you press the throttle beyond 1% the IAC opens to the park position. Ensure that the secondary linkage is completely closed (both visually and manually.). I have installed my Sniper and the car runs great. I set it exactly like the instructions said and my iac is not only all over the place but when I finally did get it to the 2-10 range it's highlighted in red. Give that a go and see if you don't make some progress! Technically it is a warranty-voiding maneuver so proceed at your own risk. It only comes back to normal if I turn the engine off and on again. the issue FYI: Car is a 1970 Mustang 302 Ford Racing roller motor. 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. shut truck off. If your RPM is 2000, your TPS is 0, and your IAC is not closing, then there is some problem. Rpm with 4-8 iac but it still shows red and shuts off randomly at idle and it won't even drive 2 miles without shutting off. Note too that the larger the throttle stab, the more brief the time in that cell and the more gradual the change.Here's what I recommend: Get somewhere where you can repeatedly stop and go. Since the load is more of a wave that increases the most initially and then decreases again, the ECU is doing really well to get the idle under control in only two or three over/under shots as you describe.You don't mention if you have your Sniper ECU controlling timing. I installed a Holley Sniper on my Ford Maverick 302 V8. I have been able to get it pretty If you're having issues with your Holley Sniper IAC getting stuck at 20, there are a few things you can try to fix the problem. Bryan McTaggart 02/28/2023 news I did buy the Sniper from you guys and the service was fantastic. Interesting question. Holley Sniper IAC Surging???? If you go the other way then you might find that the IAC zero's out when the fans are off. These aren't generic newsletters either but instead personalized emails. The noise is definitely coming OUT of the throttle body. If you use your handheld to go here: If the screen shows iac at 0 and you block the hole to find it open what does that mean? The idle will not return to the set value.The second issue is the same as the first but the motor will stall out. 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. After it starts it idles around my 960rpm setting + or - 100rpm. Again, I would lean on that solution to let the vehicle drive/learn before you try to "fix" anything. Except at idle. If it does then you can put on a heavier spring so the advance doesn't come in as fast, or use a lighter weight. I did notice that when I thought I had it set Unfortunately I did not buy my sniper efi from you. When I turn it off and try to restart it just cranks. :-)Yes, learn impacts idle too, and remember the even when the basic learning is done there will continue to be some learning for changes in weather, altitude, etc.Go ahead and try a few idle settings and see how they impact the idle-speed searching. I'm new to the efi thing and any help would be seriously appreciated. ChrisI finally got everything resolved. The next time it happens is the perfect opportunity to find the problem. Very annoying ended up being simple my rear plates would stay open constantly it was driving me nuts I'd let off the pedal idle at 1300 blip the throttle a few times finally come back to 850. And increasing your idle via the idle screw was also a good idea, because that will lower your amount of IAC that is necessary to keep your engine at the target idle speed. I have a Holley Sniper EFI with HyperSpark ignition. So, if pressing the throttle is making it start, it's because you're flooded.Which is consistent with your rich idle condition comment, right? Good afternoon Chris, thanks for taking the time to help all of these folks that didn't purchase from you- myself included!The issue I seem to be having is at idle in both park/neutral and drive. An undersized or partially plugged fuel filter is a classic EFI installation mistake. Should i adjust idle screw with the fans already on? Then a little faster--until bogs at that level work themselves out. No power at the programmer and no fuel pump running. This is actually more troubling than the sound you originally described. P.S. Featured Products Sniper EFI $7.07 - $2,457.95 470 Products View Parts author Staff Writer 1711 Posts An Article About Video tech Sniper EFI Videos Sniper EFI Tech Sniper EFI sniper Installation I've changed all the These are "transitional" cells, and you really have to make the effort to learn in these areas of the map. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. )Take a look at your AFR during the starting process. It might be necessary to insulate or re-route your fuel lines if this can't be solved any other way. If there is an issue with using the Sniper EFI TPS signal, is there a remote TPS or an adaptor for the Sniper EFI that allows the TPS signal to be accessed for the transmission. The learn function will offset the base fuel table until the closed-loop compensation only requires minimal changes. have the system learn the higher speeds? (It should be at or near 60 PSI at idle. (Note: in the original version of this post we had a section about checking the idle speed curve setting. I'm going to jump out on a limb here and say you either don't have adequate fuel flow or pressure. That is certainly not normal! Take a drive and stop somewhere for 30 minutes, CTS is 170 when engine was shutoff. No problems with either cold or hot starts. Don't know if I should put this in a separate post. any ideas? If the issue persists, you may need to replace the IAC. When this occurs, I sometimes can shut it down and it will return to the correct settiings. You've got it running and warmed up but now you need to set. A good example of why it's so important to run a good pre filter in the fuel line. As inconvenient as it might seem, I'd recommend keeping a timing light handy and checking your timing during the high idle condition and then again after restarting. I would suspect something is coming loose causing a stop to the EFI system/Fuel flow. Start engine let it warm up to 160, learn mode is learning. I've read that a spacer with 4 individual holes will solve this, but after I installed the progressive linkage the noise went away!! One thing you need to sync the timing and set the inductive delay. Anyway I have a 327 sbc in a 1987 Monte SS with a T5 5 speed and 3:73 posi rear. Keep in mind that at 60 miles the Sorry for all the questions, new to the efi world. However, I have never found that to be the case. Fortunately, these are much easier to solve. Now it's at 5% on a big cam 440 Mopar. I am having an issue with the IAC on the Sniper. I'm running a 408 sbc. Maybe give it a half-turn before you start it and then start and tweak. With an assistant pressing the accelerator, you need to make sure that when the accelerator is pressed to WOT that the throttle blades are fully opened, and when accelerator is lifted the linkage is fully at rest against the idle speed screw. I had a customer who struggled to understand that. You can disable the idle spark control at the locations below. That, on top of your air leak, is allowing the engine to idle at 2400 RPM. Yes, let me know how that setup process works. Holley Sniper IAC Problem 04-26-2018, 11:30 AM Hello. The idle is 1350-1400 with the idle screw at initial contact. It really takes a lot of throttle tip-ins before you get anywhere near "learned" in this part of the fuel map.Based on your description, it sounds like you have a lean stumble. I didn't find your site until I was having trouble. Is that normal? We can not hit it at all, we hit the pedal abruptly, the engine gives a lot of excess fuel, the AFR gets super poor at first, the car stops, then the AFR gets super rich and the car runs until it cleans up. The throttle position should be zero. I think that a great number of the challenges that Sniper EFI System Owners face are brought on themselves by getting into the control settings before the system has really had a chance to learn. I' m going to put the 3 rd new pump this coming friday. Im not sure what its doing, have messed with after start fuel, fuel at cranking. You can drop it down and you will find it will behave more like you expect. If you get into the practice of hearing all three of these sounds you will know if you have a problem even before you turn the key to crank. That initial rev is going to be determined by your IAC Park Position. Glad to hear that things are working well! If the solutions suggested above are not working then you need to review my article on IAC Testing Procedures. However I do have a couple of issues I hope you can help me resolve. Pricing was reasonable, shipping was prompt and Chris helped me with a wiring question during my install. But, if the idle is so high that it is making you crazy then you might try dropping that number just a bit. I'd recommend you contact Holley Tech support to get their input (1-866-464-6553; call early for the shortest wait times.) IAC Pos.% = 0 EFI Systems based on Holley's world-class Dominator and HP ECU's. If the ECU has not spent some significant time learning yet, I'd recommend going back through the setup wizard and getting everything back to default. I ask because I'm using a PCV valve with my Sniper and have random idle issues as well. I have it set at 650 and it idles anywhere from 590 to 700. I will a, Scott has been very helpful and informative on guiding me through the purchasing and installation of my terminator X max system. Try it! This page was generated at 12:26 AM. It's hard to know what the previous owner did right versus wrong. When the system is up and running the fuel pressure regulator inside the Sniper is making a rattling sound like a shaking a paint can. Drives just fine but won't stay running unless I keep my foot on the gas. If the TPS is even just 2%, the IAC will go to the hold position (normally 30%) and will not change until the TPS goes back below 2%.If you create a datalog you will be better able to confirm if something is not working correctly. 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. Ive had an idle at neutral as high as 2400 rpm. That is the default "Clear Flood" TPS setting and turns all fuel off until the engine cranks. Holley EFI Electronic Fuel Pressure GaugeI think its a little ridiculous that I cant see fuel pressure on the display even though its measuring it but whatever. A few, however, get tangled up getting the idle control working just the way they want. It would be possible to set up a 1D or 2D table and do something like this, so if you've gotten into these advanced setups then that would be another thing to check.If neither of these work then I'd recommend that you do a data log of the engine idling as the temperature is reaching and then exceeding 200 degrees. Those don't impact the way the engine runs and can cause the whistle sound you describe. Why is this? This was an issue in the earliest version of the Sniper firmware. But he kept having problems so eventually he did a complete check and then he found the problem. You can find those settings here: Handheld: Tuning > Advanced > Advanced Idle > Rampdown, Software: Idle > IAC Settings > IAC Ramp Down. You mentioned going from 13.5 to 14.2 but you'd want to go in the other direction--maybe to 13.2. Running the vacuum advance and of course I time it disconnected. Chris I am having a little different idle problem I did your -40 thing and that help with high idle but my problem is it idles fine until I drop it in gear and it stumbles a couple times catches up and then idles fine again. When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC. Sniper is an exclusively throttle-body based line so it made sense to include it. Both answers you've received greatly oversimplify the truth in favor of the answerer. Relatively new Sniper EFI install on a '69 Mustang 302. I have probably 200 - 300 miles on this engine and it has always done this. Incorrect connections will result in excessive resistance. My dad wanted to recheck the timing so I set the Static Timing at 15 and it runs perfect. As I have it set right now, my idle at park is in the high 700s and my desired idle in gear is set at about 700 cold (80 degrees) and gradually lowers to 590 once engine temp reaches 160 degrees. I went on the good ole interweb and found your website which was VERY helpful! This is more of a bit of a reality check. My issue is that the TP% will not reset with key cycle and its idleing at 9% TP. Advanced throttle body injection systems capable of transmission control and more. Since your target is probably more like 700, and since 2400 is way over 1700 RPM, it's going to leave the IAC in the park position.Buckle down and find how air is getting into your engine. Thank you for your input. THANK YOU for the "First--Check Your Idle Speed Curve Setting!" To figure this out it's going to be important to gather a bit more data. It is how the engineers allow you to clear a flood condition when you detect it. If that tested out okay then I can really guess that there might be some sort of intermittent, temporary RFI. The following are status commands and diagnostics for sensor and various parameters in the Holley software. 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. To do this, open up the Initial Startup gauge screen that was used in section 17.0. :-). About two minutes after I get it set at 850 & 5%, it has progressed to 100%. I have seen this become blocked with debris / dirt in the fuel system and cause a high fuel pressure condition . Also ensure the TPS Position returns to zero at idle, & the IAC Hold Position isn't setup too high. But there are several degrees of play there in which it should still work fine. Well you were right air was entering from another source. As far as the timing light, I don't know, because I was having problems getting it to work, and that's where I stopped. If the connection is loose it will cause the system to shut fuel off because the signal telling the EFI the motor is turning stops (to prevent excess fuel from being dumped in the motor). Do please let us know what you find out! WIthout knowing quite a bit more it will be more than challenging for you to identify the problem and solve it.Fortunately, Holley provides their amazing Sniper Software. I've abbreviated it just a little bit but am appreciative of the added insight your comments provided.Off-idle performance can really be a challenge to self-learn but be assured that it can almost always be done. Of the two options, I generally recommend the self-learn. Then do it just a bit faster--just enough for it to bog a bit. If idle drops below 800 it wont come back itll chug around 300 rpm for a few seconds then die. (I'm running from a fuel cell on the garage floor 10 feet away with lines in plain sight and do see fuel coming from the return at a decent flow.

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