In this short video you learn to replace the IAC. That's a nice change of pace--a low idle issue! The first thing I'd do is check your fuel pressure with a gauge like this. 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%. What an amazing site you have here. I've helped folks work through a number of challenges with their Sniper EFI System installations. 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. Yes, you are correct. I' m going to put the 3 rd new pump this coming friday. Seems like its too slow to grab idle when ac kicks on. Both answers you've received greatly oversimplify the truth in favor of the answerer. The on board fuel pressure regulator in the Sniper throttle body has a small filter clipped over one end . I was shocked to see it at 95lbs!! I hope everyone enjoys this v. 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. Adding a wrap to the return spring on the shaft is one alternative to solving this. Coming home from work today it was much warmer and took a little longer due to traffic. Holley Sniper EFI Problems: Best Fixes According to Manufacturer This only happens when coming to a stop and the idle is ramping down to the set idle RPM. Bolt on 4150 Flange Carburetor Replacement. When I start the motor I have to push on the accelerator pedal for the motor to start. Since that has long been corrected we have moved that information to the bottom of the article.). 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. Fortunately, I have an article that goes into this in some detail. That is what I really respect about Holley. You might have a bad IAC, but you can also have a bad vacuum pod on the 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. Then Friday night as I was driving home, the car started acting up. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. 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. If idle drops below 800 it wont come back itll chug around 300 rpm for a few seconds then die. 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. Except at idle. Now that you've got your IAC set I'm going to recommend that you run your setup wizard again, which will reset the ECU to the default settings. Is that normal? It only lowers to 2-6% when I take my foot off the gas. Is there away to program the ecu to compensate for this at start up. I am Japanese who attached Sniper EFI. Hello. I can adjust at 160deg, but my fans turn on at 180deg. AGAIN This is Intermittent meaning on a recent trip I stopped 3 times and issued occurred once. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. 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. I do know that the reference angle is 57.5, the inductive delay says 100.0. The "PC Text" indicates what will be shown on the PC/Laptop data monitor or data logger. If you suspect this then try to find a situation where this occurs where you can safely check the secondary throttle shaft and see if i's slightly open. To be honest, you sound like an ideal candidate for Sniper ECU ignition timing control. 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. Should it not do the opposite and do this on a cold start not warm. Then, when you experience the high idle, note if the IAC number has increased. These aren't generic newsletters either but instead personalized emails. Hot start it most of the time wont start unless I give it a little throttle. But as you see from the recent revision I did above you seem to be having a fixable issue. Both Sniper and trans controller grounds were direct to the battery ground, as they should be. 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. But if you can datalog the bog you can know much more precisely what is happening. I think you'll be all set! IAC Testing Procedure for EFI Systems What would cause the idle to faulter like that? 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 Hang in there--you can do it. You'll have to go back and forth a couple of times to get it just right. Thank you for any advice. Did your process to adjust idle to 860. Price Point: $$, Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps. 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. I put sniper on in hopes to be able to just turn key and start without fumbling with pedal to keep it going and to correct idle drop when ac kicks on. The problem was RF interferance . However based on your reply I connected the Fuel Pressure gauge and Hi Chris , greetings from Down Under (AUS) Just a note on the hi fuel pressure issue . Start engine let it warm up to 160, learn mode is learning. 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. What you are experiencing is rather common. It shuts off when coming to a stop sign, at any cruising speed and romdomly at idle in park but never when excelerating. If you've been running a filter then you have to wonder if you have a legitimate Walbro pump.If you install a new pump and the noise is still coming from the Sniper EFI System then only the dealer who sold you your system can help you. Hopefully replacing the pump again will resolve both issuesWhoa. Yes, having an accurate TPS is very important at idle. All times are GMT-6. A good example of why it's so important to run a good pre filter in the fuel line. Going lower with the blanking might pay dividends, but there is so little room below 7/8 that you will quickly be in a range where every tiny variation in the TPS or MAP is throwing extra fuel into the engine. It works instantly for him.If that fixes your problem then you have a starting place. I guess we can't have everything. started up the engine. I did change the -40 thing also. I think that your Sniper system is working fine but would definitely check ouf the fuel pump. Not that I noticed. If Not good.There isn't set solution here that works for all engines. There's a procedure there I can share with you if you'd like.. 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. 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. They also worked with me on a sale I missed and price matched those parts. Thanks again Chris, your help has been invaluable.If anyone is considering going EFI, Chris is the man to chat with. Setup: 1965 Impala SS; ZZ6 Crate Engine, EFI Distributor. On startup- cold or hot, I get a 2 second high idle of about 1500 RPM before normal set idle of 750 RPM happens. Could be a bad IAC motor, replace it and see if that solves the problem. Price Point: $, Advanced throttle body injection systems capable of transmission control and more. When the lambda is 1.0, the displayed AFR is 14.7;1 REGARDLESS OF THE FUEL. Super helpful and knowledgeable. When I put it in park the idle RPM was 2100-2200 each time. 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. 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. All EFI systems need a large fuel filter to trap dirt and yet not reduce volume. Repeat until that stumble goes away, and then try a bit more throttle. After 50 on the throttle position I'm not sure if the whistle goes away or you just can't here it anymore. The engine has 14: 1 compression ratio, we can not use gasoline. 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. There is no sense proceeding until your TPS is at zero at key-on. IAC Pos.% = 0 If I adjust idle screw out to get the tps to zero or even 1% the engine will not idle. The Sniper EFI Manal says not to but many EFI installers have informed me that the transmission only reads the 5V TPS signal from the Sniper EFI & does not draw any power so will not affect the Sniper EFI TPS output. I would disregard any correlation between idle control between the Stock and Street/Strip setups. Then it will ramp down to 1200 but will not return to idle. :-). The IAC going to 30 is normal. I have an adapter on the manifold for squarebore to spreadbore and then a phenolic spacer. They always responded to my questions with guidance that helped me choose the right system for me. 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. I'm so glad you found this helpful--that makes my day!Don't get too concerned about the specific learn percentage. Make sure that your blanking level is _below_ that (being careful not to find yourself in the situation I describe above.) Holley documentation and videos didn't work and the $300 I paid for "expert" tuning didn't work either. We have never had that problem with any of the units that we have shipped. 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). Save Share. So this is my issue ( I did just email Holly). Any suggestions would be appreciated. So I had my Idle set up perfect, with idle timing control off and engine hot the IAC was right at 2-4%. 90% of time with engine hot. You will find a startup IAC percentage, an amount of time it holds at that percentage, and an amount of time it takes to idle down to the normal idle speed.By default, that number is 50% at normal operating temperature. The throttle position should be zero. 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. 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. When you open your IAC to 30% you are naturally going to have a high idle condition. :-). The car would idle, I could hit the gas rev the car up and it ran great I also noticed two nice black spots on my garage floor from the exhaust. We are using Target AFR of 9.0: 1, Fuel Base approximately 40% higher. 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. Now I have most of the bugs worked out it runs fine on the highway and around town it's just the idle. Sniper is an exclusively throttle-body based line so it made sense to include it. I would continue checking the electrical connections along the fuel supply. Only in the unlikely event that your engine simply won't run well enough to drive and self-learn should you consider tweaking anything inside of the first several hundred miles. If you haven't confirmed that they it is worth checking. 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. You just need to go back through the IAC adjustment procedure now that idle timing control is enabled. Always had to set idle above 950. To do this, open up the Initial Startup gauge screen that was used in section 17.0. You'll be amazed at how much of this just "goes away" when you drive it enough. Data logs show no EMI/RFI. Can the return line be an issue?I have had 2 faulty gpa-4 255 walbro pumps go bad. To figure this out it's going to be important to gather a bit more data. I took some pics of the sensors page this morning after the car warmed up. This is Intermittent meaning, I can run this test 5 times and IAC will function incorrectly 2 out of the 5 times. 30 minutes later CTS reads 161, start engine Idle is jumping from 450 (almost stall) to 1500, IAC is jumping all over 10 90. I've been messing around for a bit trying to eliminate any possible vacuum leaks. After a stall the car will restart but will be in a high idle. Your issues are likely related to one of these two things. The Tech Tips and discussions are also great! Does this seem reasonable and how hard will it be to get the idle and off-idle performance correct? 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. Have a look--I think this is going to allow you to fix your idle problem. Okay, try my method. Ok, so there are a couple peculiar things going on here. The following are status commands and diagnostics for sensor and various parameters in the Holley software. I have it set at 650 and it idles anywhere from 590 to 700. Sniper EFI Problems - Holley Performance Products Forums It might be necessary to insulate or re-route your fuel lines if this can't be solved any other way. If no air is passing (and the idle doesn't drop) then your IAC is working. Definitely not 90. )Since this isn't a consistent issue with all Snipers that tells me that different IAC settings tend to make the whistle. Cheers Darren. I have replaced the IAC motor and the problem remains. Worst case you'll have a spare on hand, and if the TPS is faulty you will have solved the mystery. Going in the direction you did (higher) is going to reduce the acceleration fueling that the engine sees. Be aware that there is a spring behind there and a diaphragm that you don't want to tear. Ensure there isn't a vacuum leak causing the IAC Position to drop to 0%. When this occurs, I sometimes can shut it down and it will return to the correct settiings. It could be that the air flow across the secondaries as they are opening is creating that whistle but that isn't commonly the case.Did you check for leaks around the gasket of the air cleaner? I recently had IAC issues identical to what you describe. Your mechanical advance will naturally change the timing a bit but it should be fairly close. I've changed all the Why is this? Shut off the engine, ensure power to the Sniper is switched off. I can have it working fine (5% to 10% at target idle at operating temp.) :-) Just don't let the parts go flying. 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. One way is to very carefully watch the handheld monitor, and that may be adequate. Also when ac kicks on it will idle down and stall. 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. At idle my IAC is 3-4, AFR around 13-14, TPS is 0, timing 15-17. 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. 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. 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. Then your low idle problem will go away. When I covered the IAC with my finger, the RPM dropped so low it stalled. It wont fire up. Enjoy your Sniper! Turning it off and back on would reset it, and then it would work as advertised for a while. Sniper EFI Update: Weeks Later, Do I Still Feel It Was Worth It? PDF Sensor Diagnostics and Statuses - Holley Jump on board now! I started with right after I first adjusted for 2% IAC and took pics about every 30 seconds over about 2 minutes. If you complete the process and find that the IAC is less than 2% at idle, repeat the process and use the set screw to make the RPM about 60 RPM below the target. Now it's at 5% on a big cam 440 Mopar. Sometimes it sounds like it wants to crank at the start but runs out of gas. Any ideas here? is train the system or there is actually something wrong.I do love the system at Running the vacuum advance and of course I time it disconnected. First, let me congratulate you on your patience in letting the system learn. Short drives is fine then it'll If there's any run time on your current setup the Sniper may have some bad learn data due to what appears to be timing issues. Sniper EFI Initial Startup and Troubleshooting Staff Writer 01/20/2020 If the regulator is working correctly and there is no restriction in the return line that should make no difference however.Sorry I didn't see this on the Holley forum. It felt like it was flooding out at low speed, low. I believe that you have this problem solved now with your new inline filter/regulator. 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. 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. Well, it sounds to me like your Sniper is doing its best to reduce your idle. The "Gauge Text" is what would be shown on a 2-1/16 gauge or the Avenger handheld display. Copyright 2022 Holley Performance Products, Inc. All right reserved. Also its extremely rich at idle. It's all part of the pleasure of EFI. NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160F! Give it a watch: https://youtu.be/7SO7-tZn6iw. Then it started behaving oddly. Next, clean the IAC and all related parts with brake cleaner. Let By the way your site and your accessory products are nice. 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. 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. But I can tell you that for most people who try this it introduces so much RFI onto the Sniper that it never works right. When the system is up and running the fuel pressure regulator inside the Sniper is making a rattling sound like a shaking a paint can. New install, when in setup wizard TPS says 90 percent and I checked the linkage and butterflies. We have shipped quite a few of these to customers in Australia and New Zealand so I know that there is becoming a good following there!We recommend this Inline 10-micron fuel filter to prevent problems like that. 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. First, check to make sure that the IAC is properly mounted and connected. No power at the programmer and no fuel pump running. I believe that for the HyperSpark the Reference Angle should be 57.5. The AFR was pretty consistent around 13. Otherwise, if removing the air cleaner eliminates the whistle then try to use a thicker gasket or try lightly greasing the gasket. it seems to ramp to 60 psi on the initial prime, but as soon as the motor start the psi spikes.I guess a workaround would be an inline return/filter regulator? 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. Target AFR at idle is 13.8%. Holley Motor Life 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. The first 250-300 miles were amazing as the Sniper EFI worked flawlessly. That is likely just confusing the issue.Instead, choose whichever setup most resembles your camshaft and stick with that. Fortunately, Holley has another product that can solve that: Hydramat.. Hydramat is not inexpensive but you won't believe what it can do. 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. Im thinking a faulty TPS. back upthe RPMs shoot up to anywhere between 1500 and 2000 and they will not get The window you saw in the image above pops up. Usually it wont stay on 0% very long and soon changes to another number like 1 or 2%. Holley Sniper IAC Problem - Holley Performance Products Forums If not then you have some other issue that is behind this increased idle. But, if the idle is so high that it is making you crazy then you might try dropping that number just a bit. It'll start & run till it's warm, then when I try setting the IAC every time, I try getting it between the 2 & 8% it quits.
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