We offer some tips to help with that. 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. close to idle with the IAC between 2% & 12%. After a stall the car will restart but will be in a high idle. Its on a big block Mopar with stock electronic ignition . Once it commands that high idle I haven't found anything to return it to normal, other than shutting it down and restarting. You have to remove all hoses in order to debug the problem. Could you provide me with some things to check or some things to adjust? If you datalog the Sniper ECU and see multiple overlapping traces for the same signal, you likely have RF-induced problems. I installed a Holley Sniper on my Ford Maverick 302 V8. Should it not do the opposite and do this on a cold start not warm. You advise would be greatly appreciated. While you have over 200 miles on the system, you must realize that in the part of the map where the ECU finds itself during lanches you might only have a total of 5-10 seconds in any given cell. May God's grace bless you in the Lord Jesus Christ. I can adjust at 160deg, but my fans turn on at 180deg. Give us a hand! The next time it happens is the perfect opportunity to find the problem. I am having an idle issue (other than that is absolutely perfect). IAC Calibration / Hanging rpms | Team Chevelle That's not the IAC Hold Position, it's a percentage value. Fuel Prime Multiplier is primarily a benefit to throttle-body based EFI systems. I am new to the EFI scene but want to learn. If I block off the iac with tape , I can get it to somewhat idle, but its not consistent. I would continue checking the electrical connections along the fuel supply. As I would slow down for a stop sign or stop light, the car would run really rough and the idle did not want to come down. When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC. 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. 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. Kind of cuts into forum time. I set the AFR at 13.5 and all is good now. Have you checked your fuel filter and made sure it's not plugged?If both of these are okay you're going to have to find a way to monitor your fuel pressure while under load. That, on top of your air leak, is allowing the engine to idle at 2400 RPM. My problem with the sniper is the whistling and hard throttle pedal, I have a 700r tranny with a kick down cable. mail today. I've been messing around for a bit trying to eliminate any possible vacuum leaks. Drive great and idles perfect at stop signs. When running it will only stay in closed loop and learn at idle. But if the idle is a little bit higher then it doesn't have to jump quite as much in response to the load, and tends to react a little bit more smoothly. It could be that you've left a vacuum port unplugged, it could be that the throttle plates are misaligned (unlikely), it could be that your IAC is not closing properly. You want to ensure that nothing is hung up in there.The only thing that I can think of that would cause the fuel pressure to spike when the motor starts is the increased fuel flow at the higher alternator voltage (jumping from 12.0 to 13.5 volts or so.) I put it in neutral and the idle RPM had increased to 2100-2200. However I do have a couple of issues I hope you can help me resolve. The timing can drift 0-30 degrees just due to the width of the rotor tip. check out the. Short drives is fine then it'll Thanks again. 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. If I put the truck in neutral the TPMS will raise all the way up over 2000. 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. Chris, port that goes right on the inlet of your Sniper and makes installation a breeze.If your fuel pressure is solid at about 60 PSI then you should start looking at The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. If you remove the air cleaner entirely and the whistle continues then you can rule that out. 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. 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. So the issue Im having is low idle. I was looking at a data log from my truck earlier this week and noted that at idle my IAC was zero. When I removed the tape and started it again, it was idling at 1400-1500 RPM and sucking a bunch of air through the IAC, even though it showed 0% on the sensors screen (pic attached). But there are several degrees of play there in which it should still work fine. It wont fire up. I have replaced the IAC motor and the problem remains. I know its not flooded because I can pour a little gas in the throttle body and play with the accelerator and it will start and run fine. Thanks! Simply go to those cells, tweak them up or down as required, and the ECU should now be able to learn its way around the bog. Generally, one of two things: a stuck throttle or noise on the TPS signal. when things aren't working and this provides just that. On startup- cold or hot, I get a 2 second high idle of about 1500 RPM before normal set idle of 750 RPM happens. An undersized or partially plugged fuel filter is a classic EFI installation mistake. Holley Sniper IAC | Chevy Nova Forum 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. But nothing beats a good solid gut-check Copyright 2017 Cyberspace Automotive Performance, Inc. All Rights Reserved. I installed Holley Sniper on three other Mavericks here in Brazil and the problem also exists.I did not make any changes to the parameters, only on Target AFR and the correction on the Idle Speed Curve chart. The fuel pressure regulator in the Sniper is fairly simple and not prone to failure, as far as I know. And the rather cavalier "Absolutely!" Properly configured, the Sniper does a fantastic job of responding to the transition from Park to Drive. Thank you in advance for your help and providing us rookies with your Remember that as an EFI System Pro customer you have access to me at any time via my cell phone. I'd say make sure you buy from someone who can give you good after-purchase help (hint!) Cycle the ignition as instructed by the handheld and then navigate to the distributor setup screen. I think that the more important point is that Holley kept sending him units until everything was working. Was perfect idle iac reading 3. At that point, with 90 PSI of fuel, the ECU can't turn the duty cycle down low enough to idle properly. 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. Until the engine starts, the throttle only has one purpose: To detect you pressing it to 60%, at which point it shuts off the fuel injectors. Cycling the power to the Sniper EFI would cure the problem, but not prevent it from coming back. 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. Based on your situation above as well as some of other experiences, I recognized that I needed to improve my tuning procedures above to better explain what steps to take if that 10-step process doesn't completely solve the problem. I believe because the TPS is not registering. You can manually set it 57 after you run the Wizard if required. started up the engine. It appears that I could now use the dongle and a laptop to custom tune for idle issues if needed. Comp. (Note: in the original version of this post we had a section about checking the idle speed curve setting. Those don't impact the way the engine runs and can cause the whistle sound you describe. Thanks. I installed a sniper efi system on my 1969 Camaro. Of the two options, I generally recommend the self-learn. I also raised idle at Park a bit with the idle screw. The problem I believe this is creating is after I start vehicle (and its still in park), the IAC drops down to my hold percentage of 10% (since throttle % is not 0) before engine is warm and therefore causing the engine to stall out. The engine might run hot but if the timing is right it should keep that heat in the engine--which is where the damage turns up. I have installed my Sniper and the car runs great. A good example of why it's so important to run a good pre filter in the fuel line. It could be a problem with the power/ground for the Sniper but much more commonly this is a result of too much RFI. My IAC and TPS show zero when it does this. I have driven it a few times maybe 100 miles or so. And all too often we don't take that extra step of using a piston stop to ensure that the timing pointer is on zero when the engine is truly and exactly at top dead center. FYI: Car is a 1970 Mustang 302 Ford Racing roller motor. % = 49 Copyright 2022 Holley Performance Products, Inc. All right reserved. I'm compltely stumped and my wife is certainly upset I'm spending so much time between the garage and the computer for something that should basically run out of the box. 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. Hopefully replacing the pump again will resolve both issuesWhoa. 63 bomb 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 could go either way.. 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. Holley Sniper IAC Problem - Holley Performance Products Forums AGAIN This is Intermittent meaning on a recent trip I stopped 3 times and issued occurred once. Or alternator? However, I have what I will call a whistle at a throttle position on 35 - 50. And the only way to be positive about that is with a gauge.Unfortunately, the Sniper does not provide an input for an electronic sender so the next best thing is an analog gauge. First, recognize that the IAC and the TPS are not inter-related in any way. Holley will take a look and tell you you have RFI and wish you good luck in finding it. Then do it just a bit faster--just enough for it to bog a bit. When I first told him to check for leaks he looked back there and said "all good". Hot start it most of the time wont start unless I give it a little throttle. Don't know if I should put this in a separate post. What you are experiencing is rather common. Start engine let it warm up to 160, learn mode is learning. The team at Holley has designed the perfect solution for your problems. that my Air/Fuel ration was 15:1 and I believe the target is 13.5:1. Even though you think your timing is perfect I'd suggest you try cranking about 5-10 degrees of advance into the distributor and just see if that doesn't work better for you.Remember this: adjustable timing pointers go out of adjustment and harmonic balancers slip. Then your low idle problem will go away. Cl. Then, the next time I cranked it, the idle went high and won't come down!" The RPM would increase for no reason. My Sniper started having a ticking noise-- I have 90 miles on my Sniper, but this started the last 10 miles or so: it still drives fine, but it worries me so i've stopped driving it for now. I pulled over and turned the car off and then back on. I think that this time around you will find that it starts and idles really well and only gets better from there. A question I cannot get a 100% answer on is can you piggy back off the Sniper EFI TPS for an electronic transmission? I have heard some guys complain that the idle is too good and they can't hear their cam anymore I'm kind of like that. We'll also be contacting you for future purchases now that I've discovered you! The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. RPM = 1200My slow gear I leave with 650 RPM, the IAC Position I leave between 5 and 6%, the This page was generated at 12:25 AM. Not to bandstand here but this is the point when where you bought your system is so important. Thanks for all your help Chris! 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. 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. It has a lightweight centrifugal spring kit installed so I reach total timing around 2500 rpm. Not that I noticed. is the fuel pressure. Did you find this enlightening? At low levels RF interference will often reset the ECU so quickly that the engine will not stall. Is there away to program the ecu to compensate for this at start up. have the system learn the higher speeds? That will at least tell you something. The IAC is hanging open and not really at 0. This software is going to allow you to open both the configuration file and the datalogs that you create, overlay them and you can get a much better idea of what is happening. Otherwise, if removing the air cleaner eliminates the whistle then try to use a thicker gasket or try lightly greasing the gasket. The Sniper Quick-Start Manual provides the following instructions for setting the idle. When the lambda is 1.0, the displayed AFR is 14.7;1 REGARDLESS OF THE FUEL. 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. Once it decides to come back down, it does so with no issue. Car was running great initially. It reads 0 at idle and when I accelerate it goes up to 30 and makes a loud sucking sound that seems to be holding the car back. In the setup, I set the hot idle for 850. I ask because I'm using a PCV valve with my Sniper and have random idle issues as well. Be aware that there is a spring behind there and a diaphragm that you don't want to tear. Holley Pro-Jection TBI Replacement Parts - JEGS I, too, wish you'd bought your Sniper from us! 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. And yes, monitoring the fuel pressure is the right answer. But as you see from the recent revision I did above you seem to be having a fixable issue. Supports up to 650hp with Four 100 Lb/Hr Injectors! Physially manipulating the linkage by hand will generally reveal if you have a sticking linkage that is preventing the TPS from returning from zero. With the engine still idling high park, set the brake, open the hood, and remove the air cleaner.