This may sound crazy but I'm going to jump out on a limb here and say you don't have an idle issue--you have a timing issue. Hello Chris. Does that make sense to you? I took some pics of the sensors page this morning after the car warmed up. I have a Holley Sniper EFI with HyperSpark ignition. 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. At this time, TPS is 0%, IAC is 50 to 60%. Use the idle speed screw to set the idle at a comfortable warm-up speed. Idle when warm was 850-ish and IAC 3-4 just as when I readjusted it the night before. It's not necessary to drive it that way. 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. 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. When this occurs, I sometimes can shut it down and it will return to the correct settiings. SNIPER EFI TO HOLLEY DUAL SYNC HARNESS Part# 558-493 $34.44 Qty: Add To Cart Idle Air Control Motor Replacement Idle Air Control (IAC) Motor for Sniper EFI TBI Systems, Sniper 90/92/102mm Throttle Bodies, Terminator TBI, Avenger 4bbl TBI, HP 4bbl TBI, Commander 950 & Digital Pro-Jection Systems Part# 543-105 $71.72 Qty: Add To Cart hard start about 1/2 throttle from stop it bogs down after 3 or 4 seconds.What I The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. nothing stays steady. And Earl's makes a fantastic little 100 PSI gauge. This will go a long way to improving your fuel map without manually adjusting the acceleration enrichment. The throttle blade adjustment is at 2-6% at hot idle, and with warm engine 185F. I have now determined with the TPS the noise correlates with the opening of the secondary butterflies. Duration @.050 is 240 intake 246 exhaust with .574/.578 lift. In the wizard I set my Idle to 500RPM but it never got slower than 800RPM, if I run the wizard again and lower to 400 RPM then it never gets lower than 700RPM.After reading about the Idle Speed curver I checked its settings and found that the curve was 300rpm faster at every point over the temp range no matter what temp I had, I adjusted the curve to match what I put in on the wizard and now the RPM is correct, I'd say you have a bug in the wizard.Idle Speed > Idle Speed Curve: Here is where the lack of coolant temperature is going to affect you. Lubricate the linkage so there isn't as much native resistance. At idle my IAC is 3-4, AFR around 13-14, TPS is 0, timing 15-17. If I block off the iac with tape , I can get it to somewhat idle, but its not consistent. Idle Tuning is a very important part of tuning any EFI system, especially our self-learning units like Sniper or Terminator X EFI. I certainly appreciate your frustration (as well as your wife's!) Once it commands that high idle I haven't found anything to return it to normal, other than shutting it down and restarting. Don't be surprised if one or the other is slightly open. When I put it in gear, it drops so low that it will stall if I don't add throttle. If the screen shows iac at 0 and you block the hole to find it open what does that mean? Engine warms up to 195 degrees and stays. In this short video you learn to replace the IAC. I would suggest you take a look at that if you haven't already. issue. I keep doing that with the same result. The first 250-300 miles were amazing as the Sniper EFI worked flawlessly. 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. Be sure to re-enable it once you get your idle tuned. For the first couple of drives it was running well, Sniper EFI was working exactly as advertised. Thanks for the information you have provided on this site. installing and cruising down the highway 70 mph I just wonder if all I have to do That initial rev is going to be determined by your IAC Park Position. It is temperature dependent but 30 is commonly where you find it. 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. Ran 2 Holley carbs and an Edelbrock. They are prone to be inaccurate. 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. Do you have any clue? I would continue checking the electrical connections along the fuel supply. I will try the other stuff when I get off work. MSD pro billet and 6AL box Yes it is controlling the timing and I had issues at first and it controlled the idle just fine. Initial thought is timing but Im running a cd box and the ecu is not controlling and I did not physically change it during the install. You'll have to go back and forth a couple of times to get it just right. I emphasize "and" because the transmission controller manufacturer I used had the TPS ground terminated within the harness to the unit's main ground, which I find to be an unthinkable choice. back to trying to zero down an idle. I am new to the EFI scene but want to learn. It is simply for the benefit of the user. I then saw you guys have an awesome little gauge that can hookup inline to the snipers existing fuel feed?? Did you find this enlightening? However, I always preach to never touch any of the controls on the handheld until you have a couple hundred miles on the engine in a range of driving situations. I will turn it up some. Follow this link to download it for free if you have not already done so. This happens no matter how much I adjust 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 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. To keep it running in gear, I have to bump the neutral idle up just over 1000 RPM. me know how it works for you. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. mean that the IAC is causing it. The IAC reads 36 when at idle fully warmed up. If you did not rotate the distributor to set the actual timing to 15 that might be the only issue. Once engine is warmed up been driving for awhile. Covered the IAC port and set idle for 850 ish. So as much as I can I have been taking off real slow and let it fall on itself to try to learn and its not learning its way out of it. 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. If you find that adding 5-10 degrees of advance helps then it's time to do reconfirm TDC. Tps is saying 26% when it at idle. When I turn the key on I can hear it prime, but I don't think im getting enough fuel. Don't try to correct for the fuel. What is it supppse to be at idle and while driving under heavy acceleration? Fortunately, Holley has another product that can solve that: Hydramat.. Hydramat is not inexpensive but you won't believe what it can do. Check the Distributor Tach Connection to the EFI. All in all, considering the system has been installed for less than 2 hours drive time we're BLOWN AWAY at how quickly it is "learning" this engine. (Don't drive and watch--get a helper!) Laptop Access I recommend confirming there is no throttle linkage issue first. If idle drops below 800 it wont come back itll chug around 300 rpm for a few seconds then die. The noise changes sound with the throttle position. Your suggestion to remove the PCV valve is just for diagnosis purposes, right? Getting the throttle blades and IAC to work together will keep your fuel injected hot rod running smooth and predictable. Holley Sniper IAC Surging???? 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. 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. Check fuel pressure too (. I can adjust at 160deg, but my fans turn on at 180deg. The Super Sniper will allow you to monifor fuel pressure if you add an electronic sender but this is not an option with the standard Sniper. 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. The Street/Strip and race cam setups tend to be too rich initially. I'd really appreciate some help. Cracked casing from a side cover screw being installed crossed threaded. Some have suggested the gasket might cause it but I've never heard of anyone fixing the whistle by adjusting the gasket (and many have tried. Its on a big block Mopar with stock electronic ignition . 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. As you have noted, each time the idle goes up. ps. Thank you so much for your follow-up. I installed another return spring for the rear plates problem solved instantly. All times are GMT-6. 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. Common killers: No filter in front of the pump, reverse wiring, driving with PWM voltage, running at dead-head pressure.Since it sounds like your pressure is right, and since the Holley system doesn't provide a PWM voltage, that pretty much rules out everything but the lack of a filter. One thing you need to sync the timing and set the inductive delay. Sometimes an engine can produce enough vacuum to pull the secondaries open slightly. I.e. If you haven't confirmed that they it is worth checking. Cl. When I finished the install on my C10, I set it as follows: 13.1 at idle, 14.2 at cruise, and 12.9 at WOT. That disappears as soon as the throttle is pressed and then you immediately revert to your timing table.You can certainly use the compressor to initate the IAC Kick, but remember that this is just a temporary idle boost to ensure that the engine doesn't die when the AC is first turned on. On EFI systems such as Holley's Sniper, all of the EFI sensors (except for the O2 and coolant temperature sender) are mounted snuggly in the throttle body. 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. I called support line he said he would have to look into it and call back. I installed the Sniper on my 1978 Ford F-100 with a small block The tps has slotted holes, can you adjust it to get to zero? 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. Take it a step at a time. https://www.gmperformancemotor.com/parts/19210007.html, http://forums.holley.com/showthread.3128#post83128, If this is your first visit, be sure to You mentioned going from 13.5 to 14.2 but you'd want to go in the other direction--maybe to 13.2. So I have been doing the slow take offs and thinking that it would learn its way out. If you have performed the adjustments above and still have RPM issues, it's time to look for clues. Let's start by not assuming anything. The biggest issue is these problems are intermittent meaning they do not occur all the time. I have certainly seen this before on other fuel injected vehicles when hot. I have probably 200 - 300 miles on this engine and it has always done this. Replacement Idle Air Control (IAC) Motor for Sniper EFI TBI Systems, Sniper 90/92/102mm Throttle Bodies, Terminator TBI, Avenger 4bbl TBI, HP 4bbl TBI, Commander 950 & Digital Pro-Jection Systems. But I wanted to go ahead and answer this so that it would make sense to someone who might not go that route.I think the first thing I'd do is try another pressure gauge. Sorta similar to a carb having the idle mixture set incorrectly (rich) or the idle speed too low. I chased that gremlin for about three weeks and was convinced I had a bad throttle cable. This only happens when coming to a stop and the idle is ramping down to the set idle RPM. Others might require 60 RPM. One of the best Ive seen so far. I did read some comments on regulator issues is there a way to check it for an issue ? At low levels RF interference will often reset the ECU so quickly that the engine will not stall. After 50 on the throttle position I'm not sure if the whistle goes away or you just can't here it anymore. I would gladly engage with you to solve this but ultimately you are going to need to go through whomever you purchased the system if a warranty return is in order. Bolt-on carburetor style EFI for your classic car or truck. The Fuel Base map is perfect, the car works well, runs well, running through the streets, the car is great. I think that the more important point is that Holley kept sending him units until everything was working. The 10 step set up on your page set my idle perfect and iac perfect a very consitant 700. If In your case, however, I think you're close to getting it running. It is a common one. ChrisI finally got everything resolved. 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. It works instantly for him.If that fixes your problem then you have a starting place. I do know that the reference angle is 57.5, the inductive delay says 100.0. Please check your process again and see if you can see very specifically what is not working correctly. The symptoms I had was a low cold start idle and going lean coming to a stop. Thank you chris for for getting back to me on this matter.I'm using russell hi pressure gas line to feed the gas up to the sniper and using the stock steel gas line that use to be the feed line for the carb to return the gas to the tank. If the engine idles at 750 RPM with the throttle plates all the way closed and the IAC at zero then there is some sort of an issue. It does this with the engine off. Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps. Earl's Mechanical Fuel Pressure GaugeI could use that for a quick troubleshooting for 1/3rd the cost of the Holley one. 2. :-). I readjusted my IAC, now it's perfect. By the way your site and your accessory products are nice. Hello. Shut off car/restart and it's back to idle at The hold position is part of the response that keeps the car from dying when you come off the throttle. If no air is passing (and the idle doesn't drop) then your IAC is working. Just add 5 or 10 degrees of advance and see if it doesn't idle better. 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. So I have been driving it for about 400 miles now to numerous car shows and going out for cruises around town, trying to work some of the bugs out from everything we did this winter, but I notice when I take off from a stop sign or I cruise at a very low speed (say30 mph) it seems to be very boggy from no throttle to about 1/8th throttle. I thought 12.0 was leaner at idle, but I figured out I was wrong.lol. Or alternator? Plus, you can email that file to me and I can be of more help. You advise would be greatly appreciated. I believe that you have this problem solved now with your new inline filter/regulator. These problems will go away when you do that. When I drive with warm engine the IAC is at 30% when pushing gas, but shouldn't it be at 0%? Can the return line be an issue?I have had 2 faulty gpa-4 255 walbro pumps go bad. 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. 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. 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. 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. As always, I recommend great restraint in changing any of the parameters until a significant amount of learning has taken place. Comp. Installed sniper on 65 galaxie. Don't make any changes more than about 10% and keep the same basic shape as the original (High/flat below 20 degrees, sloped downward up to 180 degress, and then flat again above that.) You have to remove all hoses in order to debug the problem. The only way to confirm RFI problems is by doing a data log. 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.) Using a Snap-on variable timing light so this is why I say timing is perfect. you have it set. Just getting it to act right at startup is a struggle. Your issues are likely related to one of these two things. check out the. I'll bet you find that you can get it working great without any manual tuning. I will confirm TDC with balancer but I have had balancer off and timed it before and after with same results. If the TPS is 1% or below then the air is coming from somewhere else. Price Point: $$, EFI Systems based on Holley's world-class Dominator and HP ECU's. The engine runs beautifully, with perfect idle at 650 RPM, but every now and then I hear the IAC give a sort of "snap" and the idle is at 1200 RPM. If this is the case then some adjustment of the linkage or the butterfly plates themselves is necessary. TP range is normal goes up to about 90% with throttle pedal to the floor. You're going to have to clean up the wiring in your engine compartment, In particular, look for spark plug wires that might be running near your throttle position sensor. When you open your IAC to 30% you are naturally going to have a high idle condition. That's a nice change of pace--a low idle issue! See these. 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. That way you can get into that part of the table that needs tuning, and you can watch your learn numbers grow. If the IAC number is increased during this high idle, review the points about high idle from tuning issues. But as you see from the recent revision I did above you seem to be having a fixable issue. Duty Cycle% = 3 The TPS will go red with a -15 and the AFR reads heating for a split second, then the idle kicks up to 2000RPM. Also ensure the TPS Position returns to zero at idle, & the IAC Hold Position isn't setup too high. We're never going to fill up your email box with nonsense. % = 49 Any suggestions would be appreciated. Why is this? Short drives is fine then it'll = 2.34 Car was running great initially. 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 drove it a bunch more yesterday afternoon/evening and the same thing happened several times. Idle quality is great, RPM is good, sometimes IAC is now between 2 and 5 exactly where it should be. 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. Chris thank you for the info. *Possible delays due to Covid-19 click for more information. The idle will not return to the set value.The second issue is the same as the first but the motor will stall out. Idle : IAC Rampdown : IAC hold positionChange this by maybe 2% in either direction. 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. They also worked with me on a sale I missed and price matched those parts. I have replaced the IAC motor and the problem remains. :-). I have a feeling it's something simple but I thought I'd ask you first before I inadvertently change something that affects other areas. As I said above, you could have a bad IAC, but then again, the IAC might be fine and there's a deeper problem such as RFI noise causing the issue or a vacuum leak that is confusing things. And the rather cavalier "Absolutely!" 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. He said they have been having an issue with these lately. :-)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. Thanks Again for your help. Intake has been on and off 3 times no change. Add To Cart. One of the great features of Holley's Sniper is the ability to set your air/fuel ratio (AFR) where you want it. Be aware that there is a spring behind there and a diaphragm that you don't want to tear. No, the idle speed curve setting isn't something that you normally worry about--and especially not down at minus 40 degrees farenheit. We've already tried adjusting the Acceleration Enrichment chart in all ways, going up and down, RoC Blanking, everything, it has no effect. )Since this isn't a consistent issue with all Snipers that tells me that different IAC settings tend to make the whistle. Since that has long been corrected we have moved that information to the bottom of the article.). If you use your handheld to go here: Copyright 2022 Holley Performance Products, Inc. All right reserved. Now that you've installed at least four Snipers it is going to be imperative that you learn to create and read datalogs. But I still get the iac at 0 and the rpm at 1200. any ideas? It could be a problem with the power/ground for the Sniper but much more commonly this is a result of too much RFI. Those little 1/8 NPT gauges are pretty inexpensive and generally pretty easy to find locally.If you confirm that the pressure is indeed 90 PSI you could pull the fuel pressure regulator apart and check it. the issue 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. Price Point: $$$. After speaking with Holley Tech Support and Tech Support from where I purchased the systemthey decided to replace it. If I put the vehicle in gear the idle gets higher with temp. So I had my Idle set up perfect, with idle timing control off and engine hot the IAC was right at 2-4%. Everything was working perfectly and I shut off the engine. Thanks for all your help Chris! The fuel pump is mounted under rocker panel as low as possible and far away from any heat. Thank you. Again, I would lean on that solution to let the vehicle drive/learn before you try to "fix" anything. Hey Chris The manifold pressure increases with the throttle opening but the RPMs are still low. Second, Holley just released over the weekend a video on how to implement a flex fuel sensor on their HP and Dominator ECU's. Definitely not 90. Have you confirmed your fuel pressure at idle is 60 PSI? Perfectif you have the original synchronous linkage. As I said I didn't buy from you so you don't owe me anything. So you installed your Holley Sniper. Car has run perfect every time and has never hesitated or stalled since. Have you ever experienced a high idle once the engine reaches 200 degrees?Ive set my idle the way you said and it works great until the engine reaches 200 degrees. 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 That will at least tell you something. You are aware of the idle-up problem. Also, I was seriously rich at idleso rich it hurt your eyes. datsun sniper efi Holley RetroBright This 1974 Datsun 620 Bulletside Cruises With The Help Of Sniper EFI Bradley Iger 01/13/2023 features Latest News sweepstakes 2023 Hemi Engine Sweepstakes Gen III Hemi Enter To Win Holley's 2023 Hemi Engine Sweepstakes For Your Chance To Win A 600+ Horsepower 392 Stroker! Im in Australia, so stuck the sniper on a 355 Holden engine with CD box. It's all part of the pleasure of EFI. One of the signs of a vehicle with a rough idle is a faulty Idle Air Control (IAC) Motor. Start with the most gradual throttle input you need to launch well, then slightly increase until you feel some stumble. Shut off the engine, ensure power to the Sniper is switched off. And thanks again for taking your time to answer these questions. 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. If you see that the ECU is commanding the IAC to 0 but there is air entering the IAC port then it's time to refer to my article on IAC Testing Procedures, Hello,I installed my sniper system on a 65 mustang, with a 302. This is Intermittent meaning, I can run this test 5 times and IAC will function incorrectly 2 out of the 5 times. Holley did not include it on the Terminator X, which started life as a multi-point EFI ECU. Please give this a try and let us know how it works! I have changed my roc/tps to 7 from 15 but that only took me out of learn mode. It's all part of the adventure! I'm wonder if the iac can cause this. Hey Tommy, we've got at least one thing in common. It is always best to get the base map as close as possible before adding acceleration enrichment. 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've read that a spacer with 4 individual holes will solve this, but after I installed the progressive linkage the noise went away!! Ensure that the secondary linkage is completely closed (both visually and manually.). Relatively new Sniper EFI install on a '69 Mustang 302. May God's grace bless you in the Lord Jesus Christ. If you datalog the Sniper ECU and see multiple overlapping traces for the same signal, you likely have RF-induced problems. After it starts it idles around my 960rpm setting + or - 100rpm. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. I've not heard of any others with this exact issue so I don't think it is a common problem. At some point you come upon problems that evade the easy answers and this is a good example. Handheld shows plenty of fuel so I dought it's an issue there. Sniper EFI Idle Tuning. While confirming, in the handheld ensure that the Reference Angle is set to 57.5 and that the Inductive Delay is set to 100. No power at the programmer and no fuel pump running. Find a lower price anywhere and we'll beat it by 5%! Yes, it will talk to you--but not with words.