Chris---I am contemplating replacing my Holley 750 on my new low vacuum 600 HP 496 with the Holley Sniper FI system. It's all part of the adventure! )Then look a the datalog and find out what TPS ROC and MAP ROC is most likely to cause the problem. Definitely would have went with you guys. The jack-rabbit start can usually be minimized by adjusting the throttle linkage. Look over all of your vacuum lines and fittings. The throttle plates are misaligned. no timing control. I hope everyone enjoys this v. Also ensure the TPS Position returns to zero at idle, & the IAC Hold Position isn't setup too high. Seems to behave more better now. The Fuel Base map is perfect, the car works well, runs well, running through the streets, the car is great. 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. I installed the Holley Sniper in my Chevelle this winter with a brand new BluePrint 496. When you key on, you will hear three distinct sounds: The ECU initializing the IAC, the fuel pump priming, and the injectors firing their prime shot. Also what would you say a desired idle should be for a 3 speed automatic ford? If you don't have a working coolant temperature sensor then it will never bring the idle speed down. First, recognize that the amount below your target where you set the hard idle will be different on different engines. While confirming, in the handheld ensure that the Reference Angle is set to 57.5 and that the Inductive Delay is set to 100. Bottom line ismy first one must have been faulty. The Tech Tips and discussions are also great! If not then you have some other issue that is behind this increased idle. Also when ac kicks on it will idle down and stall. I used the Casper's Electronics 108103 splitter and carefully soldered my connections. 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 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! I've made all the adjustments, all the settings, and the IAC issue is driving me crazy. I have quadruple checked my wiring and am certain it's correct. If your RPM is 2000, your TPS is 0, and your IAC is not closing, then there is some problem. any ideas? Its timed to 36 degrees. Perfectif you have the original synchronous linkage. Eventually the IAC will drop back to zero, I'll readjust it to 850 RPM & 2-9%, and then watch it steadily climb again. Jump on board now! Idle quality is great, RPM is good, sometimes IAC is jumping around from 35 to 60. Adding a wrap to the return spring on the shaft is one alternative to solving this. Is there any chance that your timing has changed since you installed your Sniper? The fuel pressure regulator in the Sniper is fairly simple and not prone to failure, as far as I know. Just getting it to act right at startup is a struggle. I'd really appreciate some help. https://www.gmperformancemotor.com/parts/19210007.html, http://forums.holley.com/showthread.3128#post83128, If this is your first visit, be sure to Reducing that a bit will help. He thought that something was wrong because when he set the idle 50 RPM below his target the resulting IAC postion was far too big. I will let you know what the results are. So the issue Im having is low idle. Turning off and then on again, the engine returns to normal. That is not something I'd ignore. You can find those settings here: Handheld: Tuning > Advanced > Advanced Idle > Rampdown, Software: Idle > IAC Settings > IAC Ramp Down. However based on your reply I connected the Fuel Pressure gauge and They tell you to ask call Holley. But if you can datalog the bog you can know much more precisely what is happening. This increased idle speed is triggered by grounding the orange wire in the 10-pin I/O harness. IAC Creeps To 100% - Holley Performance Products Forums That is certainly not normal! The AFR was pretty consistent around 13. This page was generated at 12:26 AM. 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. It is good to at least know that the Sniper fuel pressure regulator can have high pressure failure issues (contrary to what I posted to Scott back on April 13th!) 680-700.I can't find any reason other than it looses where it is in the firmware with That, I am afraid, is going to involve a little bit of luck if you don't want to create a 250 MB data log. I've helped folks work through a number of challenges with their Sniper EFI System installations. It's a Chevy 350 bored .030" over it has a cam in it what I was told is the cam has the firing order swapped. issue. Both answers you've received greatly oversimplify the truth in favor of the answerer. Please help. I have one customer who is having some similar issues and his AFR is down at 9.6:1 when it won't start. I did buy the Sniper from you guys and the service was fantastic. Thank you. I know this is old, but I bought and installed a Sniper kit in 9/18. Yes it is controlling the timing and I had issues at first and it controlled the idle just fine. I have a set of 8.8 Accel Rfi suppression wires on it. Even at 0% it's sucking a bunch of air through the IAC port. But he kept having problems so eventually he did a complete check and then he found the problem. 90% of time with engine hot. I think in some of the Wizards with the handheld it doesn't use 57.5 as the default. The fix? If you did not rotate the distributor to set the actual timing to 15 that might be the only issue. Throttle body mounted ECU - no extra boxes to mount. If either of these is not the case it must be remedied.After you have done this then you might want to involve Holley Tech Support about the TPS, or it may be easier/faster just to visit the local auto parts store and pick up a new TPS and install it. Your issues are likely related to one of these two things. Sniper EFI offers superior throttle response and wide-open throttle power. This happens no matter how much I adjust the idle screw. (If you do this you will need to reset the -40 degree setting mentioned at the top of this article. The TPS will go red with a -15 and the AFR reads heating for a split second, then the idle kicks up to 2000RPM. 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. Please check your process again and see if you can see very specifically what is not working correctly. Switch power to the Sniper on and crank the engine. If I go any more it will ping. I have now determined with the TPS the noise correlates with the opening of the secondary butterflies. Thanks again for your insights! Yes, let me know how that setup process works. Ensure that the secondary linkage is completely closed (both visually and manually.). The throttle blade adjustment is at 2-6% at hot idle, and with warm engine 185F. Don't try to correct for the fuel. Hi Chris, I have a lean stumble on throttle tip in 2-3% tps taking off from a stop light the afr will go to 19afr and the engine will stumble for a split second. 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. MSD pro billet and 6AL box knowledge with the sniper efi setup. Sniper EFI Idle Tuning - Holley Motor Life Ive also used another snap on light to confirm. Holley Sniper EFI 550-552 Holley Sniper EFI Autolite 1100 - Gold Holley Sniper high RPM - IAC problem? And thanks again for taking your time to answer these questions. TPS 0. About two minutes after I get it set at 850 & 5%, it has progressed to 100%. THANK YOU for the "First--Check Your Idle Speed Curve Setting!" IAC percentage is 5 to 10% when idling with fans on, What you're experiencing is the delay time between the ECU sensing the additional load and the IAC actually increasing the RPM. I followed the instructions and set the IAC to 2-9% when warm with idle at 850 RPM. I would only play with this if you are finding that the other adjustments I suggested aren't working. After it starts it idles around my 960rpm setting + or - 100rpm. There is a chance that the IAC is open but displaying 0% so start by putting your finger over the IAC opening. Throttle Tip-In puts you in a part of the fuel map where you stay for only milliseconds at a time. Thanks Again for your help. Hello, I am having a tps and idle issue. It only comes back to normal if I turn the engine off and on again. I did check for the lightning under the hood but all was well. When I first told him to check for leaks he looked back there and said "all good". Coming home from work today it was much warmer and took a little longer due to traffic. Shut it off and immediately restarted and idle was now 880 with IAC at 8.If this is a vacuum leak I can't figure out what would cause it to go away immediately after shutting down the car and restarting. I have double checked everythingincluding fuel pressureand have followed the directions to a T.I plan on trying your 10 step process as soon as I get a chance. 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. When you open your IAC to 30% you are naturally going to have a high idle condition. It felt like it was flooding out at low speed, low. They always responded to my questions with guidance that helped me choose the right system for me. However, I have what I will call a whistle at a throttle position on 35 - 50. For the first couple of drives it was running well, Sniper EFI was working exactly as advertised. Everything was working perfectly and I shut off the engine. Was perfect idle iac reading 3. 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 We are using Target AFR of 9.0: 1, Fuel Base approximately 40% higher. I took some pics of the sensors page this morning after the car warmed up. But I think it is safe to say that you are now at a point were some manual tuning is a good idea. Chris, Thanks for the info Chris. Copyright 2022 Holley Performance Products, Inc. All right reserved. 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. See these. installing and cruising down the highway 70 mph I just wonder if all I have to do After this whole process, the car normally rotates without a very abrupt pedal. Just thought I'd ask as there isn't a lot of info out there. around 45 mph it bogs down, catches itself, bogs, catches, bogs and catches. What could be the cause? Why is this? We'll also be contacting you for future purchases now that I've discovered you! It then idles up from 750 to 1100. If that tested out okay then I can really guess that there might be some sort of intermittent, temporary RFI. Enjoy! engine works beautiful, the car runs a lot, but suddenly, the engine does that. 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. :-DStill, I hate to leave someone hanging so I'll try to help. Thank you for any advice. Even at 0% it's sucking a bunch of air through the IAC port. If not then I think you are going to find that this will solve much of your problem. :-). I have an entire article on choosing between Sniper and Terminator X throttle body solutions and while Sniper is still a sound choice for some applications, Terminator X (with transmission control) is hands-down the way to go for those who need that. 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. I have a Holley Sniper for almost 11 month now and it was running fine with no problems until now. As always, I recommend great restraint in changing any of the parameters until a significant amount of learning has taken place. That could be a problem with the TPS or it could be some sort of throttle linkage issue. But when you have it then you can look for exactly what the IAC is doing at that point, and if there is anything that might lead to this happening. This may require shortening or lengthening a rod. Now it's at 5% on a big cam 440 Mopar. Price Point: $$, Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps. Capability Range: Advanced One of the signs of a vehicle with a rough idle is a faulty Idle Air Control (IAC) Motor. 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. What I would recommend is getting somewhere that you can spend a significant amount of time doing starts. FYI: Car is a 1970 Mustang 302 Ford Racing roller motor. 400 engine, C6 3 speed automatic, with standard canister coil for ignition, and My dad wanted to recheck the timing so I set the Static Timing at 15 and it runs perfect. Should it not do the opposite and do this on a cold start not warm. Definitely not 90. If you datalog the Sniper ECU and see multiple overlapping traces for the same signal, you likely have RF-induced problems. This page was generated at 12:25 AM. That will happen occasionally, but less as time goes and on and the engine tune stabilizes. My IAC and TPS show zero when it does this. If you look down and your TPS is 2% then either your throttle is stuck slightly open (which itself will cause the idle-up) or RFI riding on the TPS signal has caused the ECU to see the throttle as open and, as a result, open the IAC to the hold position. idle counts from 0. By the way your site and your accessory products are nice. What should I be looking at to calm this down? And if you're going to go this route I'd recommend that you switch from "Simple" (3 A/F targets, one each for Idle, Cruise, and WOT) and go to the 2-D Table Hi I wish I had bought from you but I didn't find this site until now. If that happens then follow my 10-step process shown above. Hi Chris thanks in advance for any tips. Let )Since this isn't a consistent issue with all Snipers that tells me that different IAC settings tend to make the whistle. Now, 1% on the TPS isn't a problem, but when it goes to 2% (which is inevitable if you have RFI moving it to 1%) then the IAC is going to go to it's hold position (30% by default) and the engine is going to rev up. And Earl's makes a fantastic little 100 PSI gauge. It shuts off when coming to a stop sign, at any cruising speed and romdomly at idle in park but never when excelerating. I was looking at a data log from my truck earlier this week and noted that at idle my IAC was zero. I ask because I'm using a PCV valve with my Sniper and have random idle issues as well. I have verified that there are no vacuum leaks, not to mention the car runs to good to have a vacuum leak bad enough to make this noise. Commanding the engine to automatically increase speed when switching into drive is a little scary to me though. My IAC was constantly at 100% at idle. *Possible delays due to Covid-19 click for more information. Duration @.050 is 240 intake 246 exhaust with .574/.578 lift. EFI Systems based on Holley's world-class Dominator and HP ECU's. You may have to register before you can post: click the register link above to proceed. If I block off the iac with tape , I can get it to somewhat idle, but its not consistent. Suddenly, the engine accelerates alone, hears a great deal of air being sucked in, I have it set at 650 and it idles anywhere from 590 to 700. If the IAC is zero, and if putting your finger over the IAC port doesn't lower it, then it's not the IAC circuit. It does this with the engine off. If ChrisI finally got everything resolved. Holley EFI Electronic Fuel Pressure Gauge, article on choosing between Sniper and Terminator X throttle body solutions. 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). 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%. My problem is low idle. Are these compatible enough? 2. 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. When you set the Static Timing to 15, what did you read with the timing light? Even though the Sniper's fuel map is programmed to provide the correct amount of fuel via injectors spraying at 60 PSI, if the pressure is jacked up to 90 PSI the wideband sees that you are rich and faster than you can even detect it audibly lowers the duty cycle to inject the correct amount of fuel. I.e. Thank you very much. It drops about 200rpm when clutch engages. But nothing beats a good solid gut-check mail today. Maybe give it a half-turn before you start it and then start and tweak. Hey Tommy, we've got at least one thing in common. Therefore The iac will always be at 10% now, correct? A couple of possibilities that come to mind in order of likelihood: Im having an issue with what I think is the Iac. I am right back to where I started. 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. Any suggestions? If you can track specific engine coolant temperatures where the engine stumbles and dies that would be a good place to start. Holley will take a look and tell you you have RFI and wish you good luck in finding it. Hey Chris 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). holley efi. You can re-enable this after you have completed this idle speed adjustment process. 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. The Sniper EFI remote IAC (Idle Air Control) and plug is designed to gain installation clearance on some Sniper EFI 2x4 installations. He said they have been having an issue with these lately. By the time I was near home, the idle in Park was 1050, IAC 0. I recently install a sniper efi. If I put the truck in neutral the TPMS will raise all the way up over 2000.