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. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. I installed a Holley Sniper on my Ford Maverick 302 V8. Thanks again Chris, your help has been invaluable.If anyone is considering going EFI, Chris is the man to chat with. That's what you're seeing. 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. Will restart but only for a minute or so a couple of times then shuts down fuel delivery and will not restart. 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. TP range is normal goes up to about 90% with throttle pedal to the floor. I had a customer recently with a high idle problem that he eventually traced to pad plug on one of the vacuum ports. If i adjust the throttle plate screw in to bring IAC in to proper range say around 7 the engine is running around 2000 rpm. Yes it is controlling the timing and I had issues at first and it controlled the idle just fine. Running new vintage air system so the is only a single power wire to compressor thats why I asked if I needed to run input wire to ac relay or if iac would pick it up fast enough(which its not). But before you adjust the ECU to lean the idle out, first confirm that your fuel pressure is right. After doing TPS reset it starts fine but when you give it some gas it hangs at 1500 and will not return to idle. A couple of those and you should feel it getting better. So you installed your Holley Sniper. You might have a bad O2 sensor, really bad exhaust leak or a problem with the ECU. Switch power to the Sniper on and crank the engine. One of the signs of a vehicle with a rough idle is a faulty Idle Air Control (IAC) Motor. 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. A problem since day 1 - YouTube Leave a comment if you've had this issue and how you resolved. Pw. and if you do run into any problems then, yes, the plethora of tunability adjustments available through either the handheld or the Sniper Software will certainly be enough to get you right where you need to be! 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. I've been trying to correct that 1% small issue/annoyance. Holley Sniper IAC Problem 04-26-2018, 11:30 AM Hello. ?I never had my Carb Cold start RPM any higher then 1600 RPM.THANK YOU. The 10 step set up on your page set my idle perfect and iac perfect a very consitant 700. Fortunately, Holley has another product that can solve that: Hydramat.. Hydramat is not inexpensive but you won't believe what it can do. Your closed loop compensation is adding a full 50% fuel. Member List; Calendar; Forum; Holley EFI; Sniper EFI; If this is your first visit, be sure to check out the FAQ by clicking the link above. In the time it takes to add your email address you can be at the top of the heap for getting the latest information from our authority. Sorry I didn't buy from you but I didn't know you had sold them. 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 then idles up from 750 to 1100. So this is my issue ( I did just email Holly). Others might require 60 RPM. I have quadruple checked my wiring and am certain it's correct. Get that thing installed and you're going to know a whole lot more about what's going on. holley efi. If you can send a data log to the vendor from who you bought your Sniper EFI System they should be willing and able to take a look and recognize RFI and then give you some ideas on solving it. )If you rule out a fuel supply issue then we're going to have to gather a few more clues. It's going to be really difficult to nail down the problem with the several simultaneous changes that you've made. Featured Products EFI - Fuel Injection $2.59 - $6,499.95 2179 Products View Parts Sensors 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. Short drives is fine then it'll Idle was around 1000 mark and iac 0. Bottom line ismy first one must have been faulty. 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'm so glad you found this helpful--that makes my day!Don't get too concerned about the specific learn percentage. any ideas? itself out and hold idleeventually stalling. I will a, Scott has been very helpful and informative on guiding me through the purchasing and installation of my terminator X max system. At some point you come upon problems that evade the easy answers and this is a good example. If I put the vehicle in gear the idle gets higher with temp. OK, I did the baseline idle speed screw setting. Next, clean the IAC and all related parts with brake cleaner. If your RPM is 2000, your TPS is 0, and your IAC is not closing, then there is some problem. After manually making the sensor go through the full range a few times, I reinstalled it and now my TP will read anywhere from 0% to 4% when I key on. Idle quality is great, RPM is good, sometimes IAC is now between 2 and 5 exactly where it should be. 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. Sniper EFI Tuning & Tech. I believe that you have this problem solved now with your new inline filter/regulator. That is certainly not normal! Just add 5 or 10 degrees of advance and see if it doesn't idle better. Also ensure the TPS Position returns to zero at idle, & the IAC Hold Position isn't setup too high. When I start the motor I have to push on the accelerator pedal for the motor to start. At that point the tps is pretty high, then shut the ignition off, pull the tape restart the engine and idle goes into hold mode and idle is through the roof. It will learn the fueling eventually either way, it's just that one might get you there a little faster.If the idle is fine at start-up but then increases after you depress the throttle then you might need to lower your IAC Hold Position a bit. I notice at 2-3% tps the iac is 18-25% and it stumbles, when the iac gets to my hold position of 30 it stops. Tuning > Advanced > Adv Idle > IAC Startup 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. I will turn it up some. Thanks in advance for any advice. A good example of why it's so important to run a good pre filter in the fuel line. Ive had an idle at neutral as high as 2400 rpm. That's not the IAC Hold Position, it's a percentage value. I have tried your 10-step idle adjust and ive adjusted the idle curve. Once you so this, and after you have your CAN-to-USB harness attached to your laptop with the Sniper software, you can see precisely the cells where the system is operating when the bog occurs. Cheers Darren. Thanks for the information you have provided on this site. Technically it is a warranty-voiding maneuver so proceed at your own risk. If I were there in person I would test the function of the IAC (see this article.) These aren't generic newsletters either but instead personalized emails. Now it registers zero and I have good idle but it will not register until it hits 60 and up. However, I can't think of a single one that was because of low vacuum. the gas it catches itself and runs fine at slower speeds. 2. This is a mighty big subject for a blog post reply, I should probably start doing some videos on this. is the fuel pressure. Though they both are indications of the amount of opening through the throttle body, the TPS is the throttle opening percentage and the IAC number tells us how far the IAC stepper motor is opening the bypass air circuit.If I understand you correctly you are saying that the TPS reads somewhat normally (traveling from 9% to 100% or so) but that when you cycle the key it once again starts at 9%. Fortunately, I have an article that goes into this in some detail. EFI parts, including the throttle body, and the problem persists.Please give me a hand. Therefore The iac will always be at 10% now, correct? NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160F! Once you know that then you can work on those problems. Several good bits here. If you do find you have RFI issues then I've written an . 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. Your mechanical advance will naturally change the timing a bit but it should be fairly close. I recently bought the car with the EFI system on it. This increased idle speed is triggered by grounding the orange wire in the 10-pin I/O harness. Either the Walbro pumps you are getting are not genuine (lots of forgeries being sold) or else you have something that is killing them. We do that but most places don't. During after-start idle, the idle will jump up to about 70% if the engine is cold, stay there about 4 seconds and then ramp down to the target idle speed for the current engine temperature. Hello Full product line and accessories at excellent pricing. At 0% it shouldn't be sucking any air through that port, correct? But he kept having problems so eventually he did a complete check and then he found the problem. Just thought I'd ask as there isn't a lot of info out there. 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. Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. The noise is definitely coming OUT of the throttle body. I cut and heat-shrink wrapped the 5V wire and then ran both the signal and ground wires all the way back to the transmission controller. This curve turns the idle speed down as the engine warms. Find a lower price anywhere and we'll beat it by 5%! The last 2 times have been shorter and one time the high idle was around 1400, this time around 1100. Even at 0% it's sucking a bunch of air through the IAC port. But nothing beats a good solid gut-check It has a lightweight centrifugal spring kit installed so I reach total timing around 2500 rpm. 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. Bolt-on carburetor style EFI for your classic car or truck. Super helpful and knowledgeable. But I am having troubles.When stepping on the accelerator slightly with idling, it will be 2000 RPM all the time. Thank you for this guide on setting IAC. Holley Sniper IAC Surging???? Yes, it will talk to you--but not with words. I installed a sniper efi system on my 1969 Camaro. In the warm state IAC adjusted to a position of 2 to 10%. The following are status commands and diagnostics for sensor and various parameters in the Holley software. IAC looks good once it finally s fires. That is the default "Clear Flood" TPS setting and turns all fuel off until the engine cranks. It is a common one. 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! Anyway I have a 327 sbc in a 1987 Monte SS with a T5 5 speed and 3:73 posi rear. When the idle speed screw is turned all the way out there should be just enough room between the bore and the blade to catch your fingernail. = 2.34 All EFI systems need a large fuel filter to trap dirt and yet not reduce volume. Turned it off and on again. Except at idle. This will tell us if the ECU thinks that it is in control of setting the idle or if it thinks that you are driving the engine speed with the pedal. I looking for your expert opinion. If not then you have some other issue that is behind this increased idle. My sniper is doing two thingsFirst issue, the idle is set at 800 and will idle fine, then There is a glitch in the system. In the context of the Sniper the AFR that is being displayed is the AFR of ethanol-free gasoline based on the lambda that is being read by the AFR. After 50 on the throttle position I'm not sure if the whistle goes away or you just can't here it anymore. When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC. 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. You can adjust this number up or down but there is really no need to change it unless the car is stalling.The sucking sound is just what happens when the Sniper EFI System is paired with certain intake manifolds. First thing I would check Otherwise, if removing the air cleaner eliminates the whistle then try to use a thicker gasket or try lightly greasing the gasket. Idle : IAC Rampdown : IAC hold positionChange this by maybe 2% in either direction. 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. My car will now start when its cold, but after about 30 seconds the idle drops down and begins to run like crap. What I would recommend is getting somewhere that you can spend a significant amount of time doing starts. I tried adjusting my IAC up to 10deg in both directions with no change. I'm new to the efi thing and any help would be seriously appreciated. The warmer the motor, the higher the idle will be at this point. It will drop down to 400 RPM then climb 500 and then shoot to 900 and then come back sometimes two or three times then catch it self an idle just fine again. My issue is that when Im in stop and go traffic, I can let off the clutch and the engine revs and doesnt quite want to come back to idle. 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. In this short video you learn to replace the IAC. I think you'll be all set! I installed the Holley Sniper in my Chevelle this winter with a brand new BluePrint 496. It only lowers to 2-6% when I take my foot off the gas. When I see that your TPS is 1%, that tells me that you may have an RFI problem. 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. Any help would b great. 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. If not then I think you are going to find that this will solve much of your problem. I followed the instructions and set the IAC to 2-9% when warm with idle at 850 RPM. I recommend you have a look:https://www.efisystempro.com/efi-pro-hangout/holley-sniper-efi-instruction/solving-sniper-rfi-problems, I recently purchased your fixed linkage to open primaries first and the throttle linkage extender to also get a smoother pedal. Good But another thing to consider is adjusting your target A/F ratio. I guess we can't have everything. I've helped folks work through a number of challenges with their Sniper EFI System installations. When I drive with warm engine the IAC is at 30% when pushing gas, but shouldn't it be at 0%? Take a drive and stop somewhere for 30 minutes, CTS is 170 when engine was shutoff. I am having an issue with the IAC on the Sniper. If I rev the engine a couple times in neutral it will finally return to idle & usually will not do it again for the rest of my trip. i'm having is I can't seem to get the truck to run faster than 45 mph at speeds That is the first thing you must find. Again, I would lean on that solution to let the vehicle drive/learn before you try to "fix" anything. Then your low idle problem will go away. MAP Sensor. In the setup, I set the hot idle for 850. Contact whomever sold you your system or Holley directly. 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. This minimizes installation time and packages really well on a diverse group of engine applications. You can drop it down and you will find it will behave more like you expect. It meets the target idle perfectly in either but if I lightly stab the throttle it tries to stall after slightly revving. Jump on board now! It's the same one that Holley puts in their Sniper Master Kits and I've never heard anyone with anything but good things to say about it. I presume your idle speed table doesn't increase at 200 degrees? 3 different fuel pumps. That is what I really respect about Holley. Maybe give it a half-turn before you start it and then start and tweak. They always responded to my questions with guidance that helped me choose the right system for me. 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. Also, I was seriously rich at idleso rich it hurt your eyes. It's hard to know what the previous owner did right versus wrong. One way is to very carefully watch the handheld monitor, and that may be adequate. If you hit the gas it pops & backfires through the throttle body. It is always best to get the base map as close as possible before adding acceleration enrichment. If I put the truck in park it comes down to idle. And thanks again for taking your time to answer these questions. 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.) Sorry for all the questions, new to the efi world. I can tell you that when things aren't working the way you wanted them to work that nothing beats knowing for-sure that you don't have a fuel supply problem. Both Sniper and trans controller grounds were direct to the battery ground, as they should be. 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.) Hi I wish I had bought from you but I didn't find this site until now. Is there away to lean the idle out? Engine has never stalled with Sniper system, once placed in Drive it just goes!!! 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. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. Intake has been on and off 3 times no change. Clearly, something is changing. Thanks. 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 did all of this before seeing the link you sent. Holley Idle Air Control Motor Idle Air Control Motor Fits the Following Applications: Sniper EFI 90 mm, 92 mm, 102 mm Throttle Bodies Digital Pro-Jection Systems Avenger 4-bbl TBI Commander 950 Terminator TBI 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. It may take a few tries. 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. 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. You just need to go back through the IAC adjustment procedure now that idle timing control is enabled. Realize that when you drop the throttle, the engine enters a condition it will only see for a fraction of a second at a time. If you use your handheld to go here: Keep in mind that at 60 miles the The only other thing I changed was accel enrich but whatever way I go doesn't seem to change anything unless I change it drastically. 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. Hopefully replacing the pump again will resolve both issuesWhoa. Inj. The resulting resistance can burn up fuel pumps, wiring and relays. 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.