If you did not rotate the distributor to set the actual timing to 15 that might be the only issue. your IAC is at zero. Duration @.050 is 240 intake 246 exhaust with .574/.578 lift. Wish I knew about it before I made my purchase. As I said I didn't buy from you so you don't owe me anything. Holley have given a new unit. Start engine let it warm up to 160, learn mode is learning. Give it a watch: https://youtu.be/7SO7-tZn6iw. 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 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. EFI Systems based on Holley's world-class Dominator and HP ECU's. These are "transitional" cells, and you really have to make the effort to learn in these areas of the map. Ran 2 Holley carbs and an Edelbrock. Check the Distributor Tach Connection to the EFI. We are using Target AFR of 9.0: 1, Fuel Base approximately 40% higher. You can re-enable this after you have completed this idle speed adjustment process. Have a look--I think this is going to allow you to fix your idle problem. Interesting situation you have. With an assistant pressing the accelerator, you need to make sure that when the accelerator is pressed to WOT that the throttle blades are fully opened, and when accelerator is lifted the linkage is fully at rest against the idle speed screw. I presume your idle speed table doesn't increase at 200 degrees? If that tested out okay then I can really guess that there might be some sort of intermittent, temporary RFI. Should I just disable idle timing control? Your second problem should be a bit more concerning. 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. If the engine will after the 4 seconds that the IAC kick drops off then it's not really going to help.At any rate, it costs you nothing to advance the ignition and see if that doesn't improve the idle, right? The Sniper Quick-Start Manual provides the following instructions for setting the idle. Also its extremely rich at idle. 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. You could go either way.. I installed a sniper efi system on my 1969 Camaro. Am I missing something. It won't take much! 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. If the connection is loose it will cause the system to shut fuel off because the signal telling the EFI the motor is turning stops (to prevent excess fuel from being dumped in the motor). When I turn the key on I can hear it prime, but I don't think im getting enough fuel. 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. The noise changes sound with the throttle position. I have tried your 10-step idle adjust and ive adjusted the idle curve. Find a lower price anywhere and we'll beat it by 5%! 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. Please check your process again and see if you can see very specifically what is not working correctly. And, hopefully, within those degrees you will find a place where you don't get the whistle. MAP Sensor. There's nothing wrong with manual tuning, but at this point that is just compensating for an inadequate fuel map. If it is already adding fuel, it may be worth expanding this into the area where the tip-in is occuring (and where there is no learning occuring. I recommend confirming there is no throttle linkage issue first. One of the most common symptoms of a Holley Sniper EFI problem is an air/fuel mixture that's too rich or too lean. first attempt but as it tries to idle down to the target RPMsit can never even I am new to the EFI scene but want to learn. See these. Take it a step at a time. I called support line he said he would have to look into it and call back. We'll also be contacting you for future purchases now that I've discovered you! What might cause the TPS to go to 2%? The tps will not auto reset to zero. :-DStill, I hate to leave someone hanging so I'll try to help. Duty Cycle% = 3 And thanks again for taking your time to answer these questions. I can adjust at 160deg, but my fans turn on at 180deg. Holley will take a look and tell you you have RFI and wish you good luck in finding it. If you patiently adjust this over the course of days you will get it just right.Again, glad this is working for you and look forward to a good report in the future! Learning to install these is great--you're about to embark on the next great adventure of advanced troubleshooting. I'm thinking it could be the fuel pressure--- since I have a new Spectra EFI tank and there's been some reports of the interior coating coming off and gumming up the pump however the sniper display DOES NOT show fuel pressure.the Sniper DOES measure fuel pressure on its own - i've confirmed that with holley techs as they told me to purchase the fuel pressure gauge that can just hook up to the 1 wire gauge harness from the Sniper. Camshaft is M-6250-B303 .480 lift intake & exhaust, duration at .050 is 224 degrees for intake & exhaust. I did change the -40 thing also. I've made all the adjustments, all the settings, and the IAC issue is driving me crazy. I would not expect that an electric fan would create a noticeable load on the engine but if it did then you'd want to set the idle screw when the fan was not running. I have an adapter on the manifold for squarebore to spreadbore and then a phenolic spacer. Reply Quote. Edit I just ordered a Holley return / regulator and cap for the sniper ouletOh, this is not an OEM Master Kit, but the fuel pump should be the same EFI Pro shipped this kit. 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. Except at idle. With everything else being right and since you can make it start by adding fuel it seems like you must have some sort of fuel pressure issue. If you remove the air cleaner entirely and the whistle continues then you can rule that out. Your AFR is pegged lean. Now it's at 5% on a big cam 440 Mopar. (Don't drive and watch--get a helper!) such high fuel pressure. No air should be able to pass. Chris---I am contemplating replacing my Holley 750 on my new low vacuum 600 HP 496 with the Holley Sniper FI system. Thanks, That is an strange situation. Reducing that a bit will help. Earl's Mechanical Fuel Pressure GaugeI could use that for a quick troubleshooting for 1/3rd the cost of the Holley one. 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. You might have a bad IAC, but you can also have a bad vacuum pod on the transmission. The last pic is with the car in Drive. Idle was around 1000 mark and iac 0. That could be a problem with the TPS or it could be some sort of throttle linkage issue. I go into much more detail about that in this article on startup tuning. EFI System Pro had everything I needed for my EFI upgrade. I appreciate everything you are saying. Thank you for any advice. The fuel pressure regulator in the Sniper is fairly simple and not prone to failure, as far as I know. 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. To start viewing messages, select the forum that you want to visit from the selection below. Once engine is warmed up been driving for awhile. Always had to set idle above 950. It starts cold fine, its just when its hot. I think in some of the Wizards with the handheld it doesn't use 57.5 as the default. THANK YOU for the "First--Check Your Idle Speed Curve Setting!" Im in Australia, so stuck the sniper on a 355 Holden engine with CD box. If I keep the rpm's up it does fine but my clutch can't keep up with this for long.Also when I cover the IAC port the engine dies. So what--you're never going to drive in minus 40 degrees, right? I'm wonder if the iac can cause this. 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 Remove the tape from the IAC breather hole and restart the engine. Bolt on 4150 Flange Carburetor Replacement. A problem since day 1 - YouTube Leave a comment if you've had this issue and how you resolved. I certainly appreciate your frustration (as well as your wife's!) Idle : IAC Rampdown : IAC hold positionChange this by maybe 2% in either direction. 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. I had a customer recently with a high idle problem that he eventually traced to pad plug on one of the vacuum ports. 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. Once you confirm the operation of your IAC then it's time to read my article on Solving RFI Problems. I have changed my roc/tps to 7 from 15 but that only took me out of learn mode. My car will now start when its cold, but after about 30 seconds the idle drops down and begins to run like crap. But there are several degrees of play there in which it should still work fine. 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%. One of the great features of Holley's Sniper is the ability to set your air/fuel ratio (AFR) where you want it. Throttle body mounted ECU - no extra boxes to mount. In the warm state IAC adjusted to a position of 2 to 10%. Tps is saying 26% when it at idle. The problem was RF interferance . At that point, with 90 PSI of fuel, the ECU can't turn the duty cycle down low enough to idle properly. Im thinking a faulty TPS. )If you rule out a fuel supply issue then we're going to have to gather a few more clues. It could be a problem with the power/ground for the Sniper but much more commonly this is a result of too much RFI. Going in the direction you did (higher) is going to reduce the acceleration fueling that the engine sees. It does this with the engine off. Hopefully replacing the pump again will resolve both issues. There is a chance that the IAC is open but displaying 0% so start by putting your finger over the IAC opening. 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. We have never had that problem with any of the units that we have shipped. 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 will let you know what the results are. You should get a light spray evenly distributed in all four barrels. You will need to change the -40 degree idle speed setting again but I recommend not touching anything else. Let's start by not assuming anything. Maybe Holley will add Fuel Prime Multiplier to Terminator X later. It might be necessary to insulate or re-route your fuel lines if this can't be solved any other way. A few, however, get tangled up getting the idle control working just the way they want. But you've got to find where air is getting into your engine.The reason it's going up as high as 2400 RPM is because once you press the throttle beyond 1% the IAC opens to the park position. But I am having troubles.When stepping on the accelerator slightly with idling, it will be 2000 RPM all the time. So I had my Idle set up perfect, with idle timing control off and engine hot the IAC was right at 2-4%. I installed my Sniper and the engine fired up great. I guess we can't have everything. around 45 mph it bogs down, catches itself, bogs, catches, bogs and catches. I very pleased with the performance, it is a huge improvement from the 800CFM carb I had on this motor. (Do this while you are cranking.) Cycled the ignition off. If not then you have some other issue that is behind this increased idle. Solution #1 Put car in gear take off and the engine runs GREAT, no issues drive for 10minutes take car out of gear and engine idles correctly IAC between 2 and 5 Solution #2 Shutoff engine wait 30 seconds, turn key wait for display to come up, start engine. ps. Bottom line ismy first one must have been faulty. When I shut it off then start it That is likely just confusing the issue.Instead, choose whichever setup most resembles your camshaft and stick with that. )Then look a the datalog and find out what TPS ROC and MAP ROC is most likely to cause the problem. I will turn it up some more.Is this something that the ECU will learn? This may require shortening or lengthening a rod. Simply use your handheld controller and go to the Tuning > Advanced > Advanced Idle > Idle Speed screen and click on the Idle Speed Curve function. Was perfect idle iac reading 3. It sounds like you need a bit more of a fuel squirt on acceleration, Brett. Your suggestion to remove the PCV valve is just for diagnosis purposes, right? But they are 100% committed to your satisfaction. I would suggest at that point you need to contact whoever is providing your tech support and find out why the default values are not working for you. I followed the instructions and set the IAC to 2-9% when warm with idle at 850 RPM. Throttle Tip-In tuning can be a bit of a challenge but I'm confident you can get this resolved, Mike.Let me start by saying that unless you've really done a lot of driving on the system in some useful learning situations then I would set this issue aside and not even think about it. 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. Every time though I can turn the car off and restart and it settles at 850 with IAC 2-4.The thing that has me puzzled is how the with the only difference in condition of the car being the restart, the idle is "fixed"Any clues on where to look next please let me know. All times are GMT-6. What can I do? 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. These problems will go away when you do that. That will at least tell you something. This is more of a bit of a reality check. Took it for a lap around the block and came back. I'm running a 408 sbc. Plus, you can email that file to me and I can be of more help. While this video is not meant for the Sniper EFI user it does provide a great overview of how your ethanol tuning adjustments must be made not only to the base fuel map but to the other configuration settings. 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'm Having trouble with the Sniper on high Idle. !I called Holley today, and before I could even described the symptoms the Anyway I have a 327 sbc in a 1987 Monte SS with a T5 5 speed and 3:73 posi rear. The fact that it ran so (at times) with 90+ PSI fuel pressure is a testimony to the Holley's closed-loop technology. Engine has never stalled with Sniper system, once placed in Drive it just goes!!! Laptop Access The data that you provide shows that you have at least two problems. Since the load is more of a wave that increases the most initially and then decreases again, the ECU is doing really well to get the idle under control in only two or three over/under shots as you describe.You don't mention if you have your Sniper ECU controlling timing. When I put it in gear, it drops so low that it will stall if I don't add throttle. I have a Holley Sniper for almost 11 month now and it was running fine with no problems until now. knowledge with the sniper efi setup. Suddenly, the engine accelerates alone, hears a great deal of air being sucked in, No, the idle speed curve setting isn't something that you normally worry about--and especially not down at minus 40 degrees farenheit. If you find that adding 5-10 degrees of advance helps then it's time to do reconfirm TDC. any ideas? (If you do this you will need to reset the -40 degree setting mentioned at the top of this article. First thing I would check It is probably that your RPM above the maximum point at which ramp-down can occur. 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. I'll have to check again tomorrow. If more info is needed just ask. I put it in neutral and the idle RPM had increased to 2100-2200. I have a Holley Sniper for almost 11 month now and it was running fine with no problems until now. Thank you for this guide on setting IAC. The biggest issue is these problems are intermittent meaning they do not occur all the time. Two months fighting, cursing, not getting any help from Holley OR the forum, and a stupid little tin plate. Thank you in advance for your help and providing us rookies with your That initial rev is going to be determined by your IAC Park Position. However I do have a couple of issues I hope you can help me resolve. If I read it correctly, the solution from the other thread seemed to fix a constant 300 or so RPM increase. 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. 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. As you see above, the Sniper is going to dump in a maximum amount of fuel at zero TPS, begins to remove acceleration enrichment at 60 percent TPS, and then removes all acceleration enrichment correction at 100% TPS. https://www.youtube.com/watch?v=2JpHlS1ymBc, If this is your first visit, be sure to When I put it in park the idle RPM was 2100-2200 each time. I'm going to jump out on a limb here and say you either don't have adequate fuel flow or pressure. The IAC going to 30 is normal. The headache is the Acceleration Enrichment. I pulled over and turned the car off and then back on. May God's grace bless you in the Lord Jesus Christ. The Sniper even has a feature that allows it to use the idle timing to control the idle speed. Once it commands that high idle I haven't found anything to return it to normal, other than shutting it down and restarting. Then do it just a bit faster--just enough for it to bog a bit. 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.