Hello Chris. You can find those settings here: Handheld: Tuning > Advanced > Advanced Idle > Rampdown, Software: Idle > IAC Settings > IAC Ramp Down. These problems will go away when you do that. I asked him a million questions and waited a long time to save up before purchasing the system and I have asked a lot of questions throughout the installation process. 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. It is always best to get the base map as close as possible before adding acceleration enrichment. Unfortunately I did not buy my sniper efi from you. Let Perfectif you have the original synchronous linkage. All times are GMT-6. 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've increased the IAC rampdown time to 8 seconds to try to combat this, but wondering if it will correct itself over time or if I need to possibly replace this TP sensor. idle counts from 0. I set the AFR at 13.5 and all is good now. 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. Then why don't you Get On The List for Emails Straight From Our Pro? Then Friday night as I was driving home, the car started acting up. I have a Holley Sniper for almost 11 month now and it was running fine with no problems until now. Pw. 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. is jumping all over the place when you experience this condition, it does not 2. 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. is the fuel pressure. Hope this helps! This can cause the engine to run rough and may even lead to engine damage. Bryan McTaggart 02/28/2023 news 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. The Sniper resets the TPS to 0% each time that you key the system on. Short drives is fine then it'll If so remove it. MSD pro billet and 6AL box 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. I think I figured some of my problems outI'll try to explain. I went on the good ole interweb and found your website which was VERY helpful! Thank you in advance for your help and providing us rookies with your In fact, it is those users who seem to end up most impressed with the system. 30 minutes later CTS reads 161, start engine Idle is jumping from 450 (almost stall) to 1500, IAC is jumping all over 10 90. Now it's at 5% on a big cam 440 Mopar. If the solutions suggested above are not working then you need to review my article on IAC Testing Procedures. Some advanced conceptsIf you have the Sniper Can-Bus to USB Adapter, you can connect your laptop, open the software to the learn table, and get a visual for where in the table you are experiencing the lean bog. No problems with either cold or hot starts. After much diagnosis, I ended up replacing the intake manifold gaskets. How can I adjust the startup speed down to about 1400 RPM? This happens no matter how much I adjust the idle screw. I'm Having trouble with the Sniper on high Idle. Getting the throttle blades and IAC to work together will keep your fuel injected hot rod running smooth and predictable. Thanks again Chris, your help has been invaluable.If anyone is considering going EFI, Chris is the man to chat with. Bolt-on carburetor style EFI for your classic car or truck. If you have an installation or start-up issue that is nagging you then please use the comments section to reply and we will gladly provide more information that we hope will be useful to you. I did notice that when I thought I had it set Advanced throttle body injection systems capable of transmission control and more. It didnt do this with the carb on it. If no air is passing (and the idle doesn't drop) then your IAC is working. Cracked casing from a side cover screw being installed crossed threaded. One additional wrap on the secondary coiled shaft spring is all that's necessary. And the rather cavalier "Absolutely!" 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.) 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. I have changed my roc/tps to 7 from 15 but that only took me out of learn mode. For someone in your position, it will become an indispensable tool in your tool box. Could you provide me with some things to check or some things to adjust? I installed my Sniper and the engine fired up great. other things that might cause the idle to faulter, but this is a good start. 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. Idle was back to normal but iac was at 0. The idle will not return to the set value.The second issue is the same as the first but the motor will stall out. Now, in my lifetime of experience with Holley ECU's that seems unlikely, but this guy sounded really sharp and had nothing to gain by convincing me of his dilemma. A problem since day 1 - YouTube Leave a comment if you've had this issue and how you resolved. Has a good size camshaft cant find any vacuum leaks. Hey Tommy, we've got at least one thing in common. 400 engine, C6 3 speed automatic, with standard canister coil for ignition, and It may take a few tries. But as you see from the recent revision I did above you seem to be having a fixable issue. applies here because it is so important to realize that just because the IAC 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. Were the additional load a simple step function it would be challenge enough for the ECU to gracefully increase the engine speed without overshooting. Hopefully replacing the pump again will resolve both issuesWhoa. You should get a light spray evenly distributed in all four barrels. I have driven car about 200 miles. 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%. The learn function will offset the base fuel table until the closed-loop compensation only requires minimal changes. Even at 0% it's sucking a bunch of air through the IAC port. The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. Once you've done this, the next natural step is to transfer the learn table to the base map, then go in and smooth out the sharp edges, which are going to be at these transitional states. 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. An undersized or partially plugged fuel filter is a classic EFI installation mistake. May God's grace bless you in the Lord Jesus Christ. It could be, but that seems unlikely.Instead, you need to look at the basics. Please advise. If I read it correctly, the solution from the other thread seemed to fix a constant 300 or so RPM increase. Your suggestion to remove the PCV valve is just for diagnosis purposes, right? I believe because the TPS is not registering. The tps has slotted holes, can you adjust it to get to zero? In the setup, I set the hot idle for 850. Hi. From herethe cycle continues and I am Idle > IAC Kick. Thank you for this guide on setting IAC. Earl's Mechanical Fuel Pressure GaugeI could use that for a quick troubleshooting for 1/3rd the cost of the Holley one. You mentioned going from 13.5 to 14.2 but you'd want to go in the other direction--maybe to 13.2. Even at 0% it's sucking a bunch of air through the IAC port. :-). Turned it off and on again. Idle quality is great, RPM is good, sometimes IAC is jumping around from 35 to 60. Duration @.050 is 240 intake 246 exhaust with .574/.578 lift. The "Gauge Text" is what would be shown on a 2-1/16 gauge or the Avenger handheld display. Hot start it most of the time wont start unless I give it a little throttle. Or is there something else I should 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 the IAC number is increased during this high idle, review the points about high idle from tuning issues. After a complete cool down it will do the same thing. We will definitely be sticking with Holley from here on out for future retro-fits. Using a Snap-on variable timing light so this is why I say timing is perfect. Idle when warm was 850-ish and IAC 3-4 just as when I readjusted it the night before. (Do this while you are cranking.) 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. idle at 1100 on the "stock" file it's better with street strip.The IAC counts will be at zero. Thanks for the information you have provided on this site. It sounds a little different from mine, since it commands a 1300 or so increase intermittently. Doesn't want to start, runs like crap. 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. There are a few tell-tale signs that can help you diagnose the problem. THANK YOU for the "First--Check Your Idle Speed Curve Setting!" Yes, it will talk to you--but not with words. But once you come off the throttle there is a minimum RPM that the ECU wants to see before it releases the IAC from the park position and that is normally 1000 RPM over the target idle. Shut off the engine, ensure power to the Sniper is switched off. 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. Hey Chris, I installed a Holley sniper on a small block 400, first start was great! 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. The team at Holley has designed the perfect solution for your problems. EFI System Pro had everything I needed for my EFI upgrade. 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. 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 So if you are trying to achieve a stoichiometric mixture in ethanol (which is achieved at an AFR of 9.0:1) then you should continue to target 14.7:1 since that is what will be displayed. I think that your Sniper system is working fine but would definitely check ouf the fuel pump. Look over all of your vacuum lines and fittings. However based on your reply I connected the Fuel Pressure gauge and 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. I have a Holley Sniper EFI with HyperSpark ignition. I would recommend that you call first thing in the morning, as they tend to get quite busy during the day and wait times can get long. Everything was working perfectly and I shut off the engine. I'm new to the efi thing and any help would be seriously appreciated. The first thing I'd do is check your fuel pressure with a gauge like this. )Then look a the datalog and find out what TPS ROC and MAP ROC is most likely to cause the problem. Maybe Holley will add Fuel Prime Multiplier to Terminator X later. Hello Chris. 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! Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. Handheld shows plenty of fuel so I dought it's an issue there. This value is itself enough to raise the idle a bit. The person I bought it from said he never could get it to run for more than a few seconds. First--besides the fact that it's not represented on the display, it is not even a parameter that you can datalog. Ok, so there are a couple peculiar things going on here. He has walked me through every question Iv. Interesting situation you have. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. 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. We have never had that problem with any of the units that we have shipped. If you did not rotate the distributor to set the actual timing to 15 that might be the only issue. I had this same exact issue. 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. 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. If you haven't confirmed that they it is worth checking. Thanks again. But nothing beats a good solid gut-check Featured Products EFI - Fuel Injection $2.59 - $6,499.95 2179 Products View Parts Sensors Thanks again for your insights! 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. In some cases, you may only be able to put as little as 10 RPM between the hard idle and the target idle. 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! The throttle plates are misaligned. Price Point: $, Advanced throttle body injection systems capable of transmission control and more. When you set the Static Timing to 15, what did you read with the timing light? This is normally used as an A/C idle-up circuit. Maybe here will work better ?Sniper High Fuel PSIMy fuel psi is over 90 according to a brand new Auto Meter pro mechanical gauge tied in at the inlet to the Sniper using an AN adapter.I did the search function on here and found a similar high PSI issue that was fixed by clearing the return line.I have checked the return line hose for kinks and have removed it and blew thru it without any back pressure. When I shut it off then start it You will have to do this until the TPS stays at 0% when the throttle is closed. Going back to what you said. In your case, however, I think you're close to getting it running. I have a 406SBC that does most everything right with this sniper setup. I had HIGH Idle issue and fixing this curve FIXED the ISSUE --- THANK YOUCan you explain what "Current Learn % means, after finally fixing the idle problem this % jump from -1 to -30% in about 5 minutes at idle with CTS @ about 170.Also when starting the car at hot the engine goes to about 2300+ RPM for a few seconds then crashes down to my Hot idle speed of 950 -- bounces a little and then smooths out. I installed a sniper efi system on my 1969 Camaro. The problem I'm having is I cant get the IAC to drop down off 100%. You'll be amazed at how much of this just "goes away" when you drive it enough. Now it registers zero and I have good idle but it will not register until it hits 60 and up. Tps is saying 26% when it at idle. you have it set. Good afternoon Chris, thanks for taking the time to help all of these folks that didn't purchase from you- myself included!The issue I seem to be having is at idle in both park/neutral and drive.