Thanks for the great question! I will try the other stuff when I get off work. There is no sense proceeding until your TPS is at zero at key-on. Both answers you've received greatly oversimplify the truth in favor of the answerer. If I'm driving along and pull up to a light and leave it in gear it idles just fine but it seems not to be able to compensate if I put it in neutral and then back and drive. I keep wondering how it was running so good with The engine has 14: 1 compression ratio, we can not use gasoline.
IAC Testing Procedure for EFI Systems Great work, expert! I am new to the EFI scene but want to learn. My IAC was constantly at 100% at idle. 680-700.I can't find any reason other than it looses where it is in the firmware with Always had to set idle above 950. It meets the target idle perfectly in either but if I lightly stab the throttle it tries to stall after slightly revving. These will fix the noise but if the performance is suffering then likely you won't see any difference since it is not likely to be related to this sound. If this is the case then I would look particularly close at the IAC hold position and IAC ramp start.Let us know what you find and what works for you! Also, I was seriously rich at idleso rich it hurt your eyes. No timing control, coil negative ignition type. Holly offers a very nice Analog-Style Fuel Pressure Gauge that is another option. I hold my foot steady in place it does this in 5 second cycles and if i let go of What must remain foremost in your mind is that the only thing that can cause the idle to increase is additional air getting into the engine. The Sniper EFI Manal says not to but many EFI installers have informed me that the transmission only reads the 5V TPS signal from the Sniper EFI & does not draw any power so will not affect the Sniper EFI TPS output. Confirm the placement of all wiring, ensure that the WBO2 sensor is positioned properly, etc. Give that a go and see if you don't make some progress! The distributor was loose. I went on the good ole interweb and found your website which was VERY helpful!
Solving Holley Sniper High Idle Issues - EFISystemPro.com Consider adding fuel in the AE vs TPS and/or AE vs MAP ROC tables in the area where the stumble is occuring.Since this is happening at such low TPS levels it is possible that your engine would prefer a lower (richer) target AFR number at idle. And yes, monitoring the fuel pressure is the right answer. any advise would be appreciated. :-) Just don't let the parts go flying. 63 bomb Thanks for the info Chris. To be honest, you sound like an ideal candidate for Sniper ECU ignition timing control. Idle quality is great, RPM is good, sometimes IAC is now between 2 and 5 exactly where it should be. Sniper EFI Tuning & Tech. I'm new to the efi thing and any help would be seriously appreciated. Plus, you can email that file to me and I can be of more help. I will a, Scott has been very helpful and informative on guiding me through the purchasing and installation of my terminator X max system. Your second problem should be a bit more concerning. Is this normal ? Seems to be working. To start viewing messages, select the forum that you want to visit from the selection below. I do know that the reference angle is 57.5, the inductive delay says 100.0. Using the handheld, navigate to Tuning > Basic > Basic Idle and ensure your target idle speed is set to the RPM you desire. It's hard to know what the previous owner did right versus wrong. We'll also be contacting you for future purchases now that I've discovered you! New install, when in setup wizard TPS says 90 percent and I checked the linkage and butterflies. Sorry for all the questions, new to the efi world. So I have been doing the slow take offs and thinking that it would learn its way out. You should get a light spray evenly distributed in all four barrels. I will turn it up some more.Is this something that the ECU will learn? The progressive link can be a great solution on standard (non-Stealth) throttle bodies but I would install this LAST after everything else is working perfectly. Try it! I figured out I was going the wrong direction when I was messing with the AFR programming. Give it a watch: https://youtu.be/7SO7-tZn6iw. After the start process, If the idle speed is higher than the target idle then the IAC should begin closing as long as the TPS is below 2%. I would not expect that an electric fan would create a noticeable load on the engine but if it did then you'd want to set the idle screw when the fan was not running. Suddenly, the engine accelerates alone, hears a great deal of air being sucked in, The Sniper ECU can use the timing to help maintain the idle speed and that will definitely be useful in that transition from Park/Neutral to Drive.If you don't have ECU-controlled timing, or if you do and it's not fully compensating, it may be necessary to increase your target idle slightly. I'd really appreciate some help. The RPM would increase for no reason. A few, however, get tangled up getting the idle control working just the way they want.
Start engine let it warm up to 160, learn mode is learning. Ensure that the secondary linkage is completely closed (both visually and manually.). Thanks for the information you have provided on this site. I have a Holley Sniper for almost 11 month now and it was running fine with no problems until now. mean that the IAC is causing it. Thanks so much for reading! Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. If The small rubber plug had a leak. Chris---I am contemplating replacing my Holley 750 on my new low vacuum 600 HP 496 with the Holley Sniper FI system. First thing I would check Yes its at 95lbs, needless to say he promised a new regulator would be in the And so glad you guys are enjoying the Sniper EFI system. In most cases the IAC (Idle Air Control) circuit is the source of the whistle. Drive great and idles perfect at stop signs. % = 49 On a cold start it will idle at 750 everytime, But if its hot start it will jump upto 1600rpm for 2 seconds then come back to 750. idle at 1100 on the "stock" file it's better with street strip.The IAC counts will be at zero. NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160F! The TPS will go red with a -15 and the AFR reads heating for a split second, then the idle kicks up to 2000RPM. Copyright 2017 Cyberspace Automotive Performance, Inc. All Rights Reserved. It is probably that your RPM above the maximum point at which ramp-down can occur. Going in the direction you did (higher) is going to reduce the acceleration fueling that the engine sees. I installed another return spring for the rear plates problem solved instantly. 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. I keep doing that with the same result. Im in Australia, so stuck the sniper on a 355 Holden engine with CD box. I started with right after I first adjusted for 2% IAC and took pics about every 30 seconds over about 2 minutes. If no air is passing (and the idle doesn't drop) then your IAC is working. Interesting situation you have. When the secondary throttle blades are centered in their bores and pivot freely, an additional return spring is not necessary. The team at EFI pro are some of the best I have ever dealt with when coming to ordering parts or having the knowledge to answer any question you may have. Does anyone have photos of this additional return spring they installed? Due to when the pump i'm using now makes a loud howling noise when it gets ran for awhile and it gets at a 1/4 tank of fuel or less. I have turned ignition off turned screw in 2 turns and turned ignition back on and tps is at 1-2% not sure whats going on. Interesting question. The problem I'm having is I cant get the IAC to drop down off 100%. 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. These problems will go away when you do that. We are using Target AFR of 9.0: 1, Fuel Base approximately 40% higher. And, hopefully, within those degrees you will find a place where you don't get the whistle. 2. Key, I believe, in this success is solid connections, resistance-free signal and ground paths, and solid RFI rejection. Worst case you'll have a spare on hand, and if the TPS is faulty you will have solved the mystery. The 5-6 times it has happened now have been after the car has been running for at least 20 minutes. That is not a huge problem but it just means the IAC has no ability to lower the idle beyond what it is running at that point. If the TPS is 1% or below then the ECU is in control--2% or greater and the ECU thinks you've got it under control. Fortunately, these are much easier to solve. I've tried repeatedly re-creating the scenario in hopes that the E.C.M.
Sniper EFI Problems - Holley Performance Products Forums If the engine will after the 4 seconds that the IAC kick drops off then it's not really going to help.At any rate, it costs you nothing to advance the ignition and see if that doesn't improve the idle, right? You might even want to add our 4-foot extension harness that will allow you to connect/disconnect the display or CAN-to-USB adapter from inside the car (rather than trying to do that leaning over the engine and under the breather. You mentioned going from 13.5 to 14.2 but you'd want to go in the other direction--maybe to 13.2. Price Point: $, Advanced throttle body injection systems capable of transmission control and more. When stopping, the brakes are unable to overcome the engine so I go to neutral just to stop fighting the engine. Sniper is still learning so it will continue to improve.Second, you may have heard the phrase, "correlation is not causation." Simply turn the idle speed screw on the linkage in until the throttle plates open enough for the idle to increase. I have a 406SBC that does most everything right with this sniper setup. It's pretty hard to get the header tubes glowing at idle with a lean AFR. Hi Chris. To keep it running in gear, I have to bump the neutral idle up just over 1000 RPM. I had a customer who struggled to understand that. By the time I was near home, the idle in Park was 1050, IAC 0. idle counts from 0. If I read it correctly, the solution from the other thread seemed to fix a constant 300 or so RPM increase. I've been messing around for a bit trying to eliminate any possible vacuum leaks. It may take a few tries. The whole topic of using the Sniper TPS for transmission control is one deserving of it's own article but I'll try to summarize a bit here. I have now determined with the TPS the noise correlates with the opening of the secondary butterflies. So you installed your Holley Sniper. Once we recognize that, the next step is to narrow down all possible sources of additional air until we discover the cause.Start by keeping an eye on your IAC number. I'll have to check again tomorrow. Ive had an idle at neutral as high as 2400 rpm. I then saw you guys have an awesome little gauge that can hookup inline to the snipers existing fuel feed?? Bolt on 4150 Flange Carburetor Replacement. 34K views 1 year ago Holley Sniper How to Set The IAC Idle air Control in 5 minutes or less. Stupid question, but where do I see if it's entering Learn mode? Chris, I'd recommend you contact Holley Tech support to get their input (1-866-464-6553; call early for the shortest wait times.) If the vendor from whom you bought the system is coming up blank on ideas then don't hesitate to contact Holley's outstanding tech support department directly at 866-464-6553. I have a bone stock 350 that I installed a Sniper on and had the same whistle noise, presumably from air going past the butterflies. The IAC is hanging open and not really at 0. Give us a hand! Thanks for any info./insight you can provide, Mark. Given the circumstances I would say that it is either the IAC motor itself or RFI but you seem to have ruled both of those out. Get a solid feeling for where it is when the engine is warm and the idle speed is correct. Definitely would have went with you guys. 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. Just thought I'd ask as there isn't a lot of info out there. But another thing to consider is adjusting your target A/F ratio. Properly configured, the Sniper does a fantastic job of responding to the transition from Park to Drive. I will be at a red light trying to brake against the engine. Your mechanical advance will naturally change the timing a bit but it should be fairly close. If you have performed the adjustments above and still have RPM issues, it's time to look for clues. When I drive with warm engine the IAC is at 30% when pushing gas, but shouldn't it be at 0%? It could be a problem with the power/ground for the Sniper but much more commonly this is a result of too much RFI. For the first couple of drives it was running well, Sniper EFI was working exactly as advertised. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. 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 Bottom line ismy first one must have been faulty. This question is really outside both the scope of what we try to discuss in the comments section as well as the overall subject of this article. It's all part of the pleasure of EFI. Car was running great initially. 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. idles good, runs amazing. When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC. Shut off the engine, ensure power to the Sniper is switched off. Hang in there--you can do it. https://www.gmperformancemotor.com/parts/19210007.html, http://forums.holley.com/showthread.3128#post83128, If this is your first visit, be sure to
Glad to hear that things are working well! As you see above, the Sniper is going to dump in a maximum amount of fuel at zero TPS, begins to remove acceleration enrichment at 60 percent TPS, and then removes all acceleration enrichment correction at 100% TPS. But get that fuel system fixed before going any further. Idles ok, runs great cruising, but from a stand still or downshifting and making a turn, when I get back into it, it wants to fall on its face. At low levels RF interference will often reset the ECU so quickly that the engine will not stall.
I would suspect something is coming loose causing a stop to the EFI system/Fuel flow.
How To Adjust Iac On Holley Sniper The idle is 1350-1400 with the idle screw at initial contact. First, recognize that the IAC and the TPS are not inter-related in any way. If I try and get the 2-10% i get all the way up to 1200 rpm. 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. First, I'm kind of insistent about not changing any of the default settings unless the vehicle absolutely will not cooperate enough to drive/learn, and only then if you have a specific understanding of the problem and a specific solution. The 10 step set up on your page set my idle perfect and iac perfect a very consitant 700. If not then you have some other issue that is behind this increased idle. If you can track specific engine coolant temperatures where the engine stumbles and dies that would be a good place to start. I think that the more important point is that Holley kept sending him units until everything was working. Do I need to try taping up the IAC port and setting the idle off the idle screw? Hope this helps! But they are 100% committed to your satisfaction. You can re-enable this after you have completed this idle speed adjustment process. If your TPS has snuck up to 2% then your IAC will be at the hold position, which by default is 30%. If you are using your Sniper EFI System to control timing, navigate to Tuning > Advanced > Advanced Idle > Idle Spark and ensure that the Idle Spark Enabled is set to Disabled. Ive tried setting the prime setting above 150 but it wont take, it always goes back to 150. It is made by one of the biggest names in fuel filters and sold under the Parts Master label so it is quality and great price in one. They also recommended that their ground be spliced into the Sniper ground as close to the Sniper as possible. With select intake manifolds, the distributor housing and IAC valve on the back of the Sniper EFI throttle body are fighting for the same . Turned it off and on again. Try it! Idle was back to normal but iac was at 0. Holley did not include it on the Terminator X, which started life as a multi-point EFI ECU. I'm new to EFI and have no idea what to try next. Cheers Darren. If you hit the gas it pops & backfires through the throttle body. This is a mighty big subject for a blog post reply, I should probably start doing some videos on this. If you go the other way then you might find that the IAC zero's out when the fans are off. One way is to very carefully watch the handheld monitor, and that may be adequate. It sounds to me like it is way retarded.In the event that the timing is right then take a look at your AFR--the actual AFR, not the target. Let me be perfectly clear: If your engine will not drop below 1350 RPM with the idle speed screw turned all the way out then you have an air leak. 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. https://www.youtube.com/watch?v=2JpHlS1ymBc, If this is your first visit, be sure to
I took some pics of the sensors page this morning after the car warmed up. The Sniper EFI remote IAC (Idle Air Control) and plug is designed to gain installation clearance on some Sniper EFI 2x4 installations. Since the shield was put on, not a single problem, not one. started up the engine. We do that but most places don't. The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. It's called tuning. It started right up and we did your idle control fix and all is good at idle. This page was generated at 12:25 AM. I've not heard of any others with this exact issue so I don't think it is a common problem. I have one customer who is having some similar issues and his AFR is down at 9.6:1 when it won't start. Is there any chance that your timing has changed since you installed your Sniper? Hopefully replacing the pump again will resolve both issues. Just getting it to act right at startup is a struggle. Thanks for your very detailed question! Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps. Idle quality is great, RPM is good, sometimes IAC is jumping around from 35 to 60. Cl. Full product line and accessories at excellent pricing. Switch power to the Sniper on and crank the engine. Shut off car/restart and it's back to idle at Thank you for any advice.
Sniper EFI Problems - Holley Performance Products Forums That is a good thing.I don't have a specific target RPM but always encourage automatic transmission users to bias the idle just a tiny bit higher than what you might otherwise. I have changed my roc/tps to 7 from 15 but that only took me out of learn mode. 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. When you first posted this I had no idea how to respond. I very pleased with the performance, it is a huge improvement from the 800CFM carb I had on this motor. We will definitely be sticking with Holley from here on out for future retro-fits. Note that sometimes you can get into a back-and-forth situation.