RPM = 1200My slow gear I leave with 650 RPM, the IAC Position I leave between 5 and 6%, the I think that this time around you will find that it starts and idles really well and only gets better from there. A simple remove & clean will remedy this . Bolt-on carburetor style EFI for your classic car or truck. For someone in your position, it will become an indispensable tool in your tool box. Enjoy your Sniper! Shut it off and immediately restarted and idle was now 880 with IAC at 8.If this is a vacuum leak I can't figure out what would cause it to go away immediately after shutting down the car and restarting. Seems to behave more better now. The fuel pump is mounted under rocker panel as low as possible and far away from any heat. Ok, so there are a couple peculiar things going on here. Interesting question. As always, I recommend great restraint in changing any of the parameters until a significant amount of learning has taken place. I certainly appreciate your frustration (as well as your wife's!) I have a Holley Sniper for almost 11 month now and it was running fine with no problems until now. I did read some comments on regulator issues is there a way to check it for an issue ? When I start the motor I have to push on the accelerator pedal for the motor to start. I keep doing that with the same result. 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. 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. Throttle body mounted ECU - no extra boxes to mount. In the Wizard, select the stock cam setting. Now it's at 5% on a big cam 440 Mopar. Advanced throttle body injection systems capable of transmission control and more. I have a set of 8.8 Accel Rfi suppression wires on it. Its on a big block Mopar with stock electronic ignition . First, recognize that the IAC and the TPS are not inter-related in any way. :-). My problem is low idle. It sounds a little different from mine, since it commands a 1300 or so increase intermittently. This will go a long way to improving your fuel map without manually adjusting the acceleration enrichment. Drives just fine but won't stay running unless I keep my foot on the gas. Turning off and then on again, the engine returns to normal. I installed the Holley Sniper in my Chevelle this winter with a brand new BluePrint 496. I have never seen issue when CTS is below 120 degrees. IAC looks good once it finally s fires. Fought a high idle issue until I changed your idle speed curve fix along with dropping the IAC hold to 10%. back to trying to zero down an idle. After the start process, If the idle speed is higher than the target idle then the IAC should begin closing as long as the TPS is below 2%. There are two ways to address this--you can let the system learn or you can manually adjust the acceleration enrichment. This is normally used as an A/C idle-up circuit. https://www.gmperformancemotor.com/parts/19210007.html, http://forums.holley.com/showthread.3128#post83128, If this is your first visit, be sure to This is extremely unreliable afrer warm. 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. OK, I did the baseline idle speed screw setting. I think you will find that it will learn its way through this. They always responded to my questions with guidance that helped me choose the right system for me. Start engine let it warm up to 160, learn mode is learning. Take it a step at a time. 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. The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. On startup- cold or hot, I get a 2 second high idle of about 1500 RPM before normal set idle of 750 RPM happens. Is this normal ? These problems will go away when you do that. While adjusting the screw if the TPS position reads begins to read higher than 0% cycling the ignition switch will recalibrate the TPS back to zero. Part# 538-13. Usually it wont stay on 0% very long and soon changes to another number like 1 or 2%. Sorry for all the questions, new to the efi world. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. View Holley Sniper EFI Self-Tuning Kit - Shiny Finish. If this is the case then some adjustment of the linkage or the butterfly plates themselves is necessary. 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. It turns out that some of the Snipers are shipping with the minus 40-degree setting drastically lower, as shown in the following image. Fortunately, I have an article that goes into this in some detail. My issue is that the TP% will not reset with key cycle and its idleing at 9% TP. Throttle Tip-In puts you in a part of the fuel map where you stay for only milliseconds at a time. 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. Price Point: $$, EFI Systems based on Holley's world-class Dominator and HP ECU's. The AFR was pretty consistent around 13. If that tested out okay then I can really guess that there might be some sort of intermittent, temporary RFI. Maybe give it a half-turn before you start it and then start and tweak. Yes, having an accurate TPS is very important at idle. Hey Chris! carburetor setup, but it does blow when I can't jump on the highway like I use Check fuel pressure too (. It starts cold fine, its just when its hot. Installed sniper on 65 galaxie. :-). Thanks, That is an strange situation. I have driven car about 200 miles. No matter what do, my idle will not drop below 1350-1400 RPM when the engine warms. That is likely just confusing the issue.Instead, choose whichever setup most resembles your camshaft and stick with that. Data logs show no EMI/RFI. The IAC is hanging open and not really at 0. Let me start with the engine not starting until you press the throttle. But they are 100% committed to your satisfaction. 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. Glad to hear that you have timing control enabled, Gary. Are these compatible enough? When I am coming to a stop, the rpms will hang at 1200-1500 rpms. Any suggestions would be appreciated. It is probably that your RPM above the maximum point at which ramp-down can occur. It will still change a bit with weather changes and when you get into infrequently-used sections of the map, but it's nothing to worry about.Regarding your idle speed immediately after start-up, that is determined by your Idle Parked Position. If I read it correctly, the solution from the other thread seemed to fix a constant 300 or so RPM increase. By the way, this is a new installation on a 69 Camaro, stock 350, dual sync, etc. Hi Chris thanks in advance for any tips. This is Intermittent meaning, I can run this test 5 times and IAC will function incorrectly 2 out of the 5 times. That way you can get into that part of the table that needs tuning, and you can watch your learn numbers grow. An undersized or partially plugged fuel filter is a classic EFI installation mistake. I have certainly seen this before on other fuel injected vehicles when hot. Thanks. It is good to at least know that the Sniper fuel pressure regulator can have high pressure failure issues (contrary to what I posted to Scott back on April 13th!) You may have to register before you can post: click the register link above to proceed. I have installed my Sniper and the car runs great. Running a bbc with coil - my timing is perfect. 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. Closed Loop Compensation rises to 100%, Do I just keep pushing it the same way to Thanks for sharing that, Jason--great info! (Grease can sometimes do the same thing as a more permanent gasket sealer without making the removal of the air cleaner such a pain.). This increased idle speed is triggered by grounding the orange wire in the 10-pin I/O harness. 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. I did check for the lightning under the hood but all was well. But I still get the iac at 0 and the rpm at 1200. Idle was back to normal but iac was at 0. 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. If you go too high then the motor will not return to your target idle when you come off the throttle. It's all part of the adventure! Worst case you'll have a spare on hand, and if the TPS is faulty you will have solved the mystery. If you do find you have RFI issues then I've written an . Engine has never stalled with Sniper system, once placed in Drive it just goes!!! Thank you for any advice. 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. Not to bandstand here but this is the point when where you bought your system is so important. The car cruises fine, and if I was to keep idle at 2000rpm the issue wont happen, its only when the car tries to ramp down to idle position.Thank you for your help, any advice would be appreciated.Thank you,Eric, Whenever we see the AFR go to "Heating" that is an indication that the ECU has been reset. One of the great features of Holley's Sniper is the ability to set your air/fuel ratio (AFR) where you want it. Let it will jerk and rpm will go up and down and AFR will be around 20 : 1 or more or less. It could be a couple of things. I had this same exact issue. (Do this while you are cranking.) 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. Copyright 2022 Holley Performance Products, Inc. All right reserved. 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 throttle position should be zero. Super helpful and knowledgeable. All times are GMT-6. In that case, and if you have an EGR valve, I might be suspicious of something going on there. >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. In the warm state IAC adjusted to a position of 2 to 10%. Do please let us know what you find out! have the system learn the higher speeds? After a stall the car will restart but will be in a high idle. Contact whomever sold you your system or Holley directly. Thanks again Chris, your help has been invaluable.If anyone is considering going EFI, Chris is the man to chat with. I ask because I'm using a PCV valve with my Sniper and have random idle issues as well. 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. After talking to Holley tech, I replaced the factory regulator and problem solved.The regulator had what appeared to be a film or something almost clear embedded in some of the screen, maybe from factory or from install, but that was my issue.PS : this page and other forums have helped me a lot. The IAC should display a 2-8% to bring the idle up to the actual target. Overview. Engine warms up to 195 degrees and stays. The weather in Ct has finally improved and I have put about 60 miles on the car with the Sniper system. hard start about 1/2 throttle from stop it bogs down after 3 or 4 seconds.What I He has walked me through every question Iv. Give that a go and see if you don't make some progress! Ilike a few othersam having idle issues. idle counts from 0. Start with the most gradual throttle input you need to launch well, then slightly increase until you feel some stumble. Bottom line ismy first one must have been faulty. any advise would be appreciated. Genuine Walbro fuel pumps are virtually bullet-proof. 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. Hey Chris 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. 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. One way is to very carefully watch the handheld monitor, and that may be adequate. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. 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.) Just getting it to act right at startup is a struggle. If you haven't installed a Sorta similar to a carb having the idle mixture set incorrectly (rich) or the idle speed too low. Idle quality is great, RPM is good, sometimes IAC is now between 2 and 5 exactly where it should be. The problem I experience is that after driving for about 10-15 minutes, the car starts idle to high. These aren't generic newsletters either but instead personalized emails. There are six different acceleration enrichment tables that you can tweak and that may be the way to go. That is the only way to fly. 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. Capability Range: Professional As soon as I got the new one installed and wiredit fired right up and did everything it was suppose to do with no issues. Both answers you've received greatly oversimplify the truth in favor of the answerer. check out the. 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. 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. First--besides the fact that it's not represented on the display, it is not even a parameter that you can datalog. Should the iac% fluctuate? I had a customer who struggled to understand that. I was 20 minutes into a drive yesterday when all of the sudden the RPM increased not commanded. 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. Hopefully replacing the pump again will resolve both issuesWhoa. When I covered the IAC with my finger, the RPM dropped so low it stalled. I have seen this become blocked with debris / dirt in the fuel system and cause a high fuel pressure condition . Thanks in advance for any advice. That I presume your idle speed table doesn't increase at 200 degrees? I did change the -40 thing also. I have turned ignition off turned screw in 2 turns and turned ignition back on and tps is at 1-2% not sure whats going on. I know this is old, but I bought and installed a Sniper kit in 9/18. One additional wrap on the secondary coiled shaft spring is all that's necessary. 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). Earl's Mechanical Fuel Pressure GaugeI could use that for a quick troubleshooting for 1/3rd the cost of the Holley one. 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. This is a mighty big subject for a blog post reply, I should probably start doing some videos on this. The RPM would increase for no reason. But get that fuel system fixed before going any further. The tps will not auto reset to zero. If you go the other way then you might find that the IAC zero's out when the fans are off. I have a Holley Sniper EFI with HyperSpark ignition. I think you'll be all set! Except at idle. If you feel you have no other choice but to run a Sniper and stand-alone controller then you can give this a try. I also noted that after some time, I could change those values as I saw fit. 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. Thanks for all your help Chris! IAC Pos.% = 0 As you have noted, each time the idle goes up. Jun 12, 2021. I have not heard of this. It won't take much! Start by doing the fastest start you can that doesn't bog. Turned it off and on again. Save Share. Don't try to correct for the fuel. is jumping all over the place when you experience this condition, it does not First, let me congratulate you on your patience in letting the system learn. All EFI systems need a large fuel filter to trap dirt and yet not reduce volume. 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. Then do it just a bit faster--just enough for it to bog a bit. That is certainly not normal! Follow this link to download it for free if you have not already done so. 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. We're never going to fill up your email box with nonsense. The engine ran so good, I would have never suspected the Fuel Pressure to be an I would start by datalogging the situation and seeing exactly what your learn table looks like in the area immediately around the tip-in. 400 engine, C6 3 speed automatic, with standard canister coil for ignition, and 90% of time with engine hot. Properly configured, the Sniper does a fantastic job of responding to the transition from Park to Drive. EFI parts, including the throttle body, and the problem persists.Please give me a hand. = 2.34 Pw. Or, at least, it should. 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. Since your target is probably more like 700, and since 2400 is way over 1700 RPM, it's going to leave the IAC in the park position.Buckle down and find how air is getting into your engine. The problem was RF interferance . It's not necessary to drive it that way. (If you do this you will need to reset the -40 degree setting mentioned at the top of this article. I would continue checking the electrical connections along the fuel supply. It then idles up from 750 to 1100. 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. I have verified that there are no vacuum leaks, not to mention the car runs to good to have a vacuum leak bad enough to make this noise. Should I just disable idle timing control? The first place my eyes go when there is any issue with the idle is to the TPS value. Let's start by not assuming anything. I think that your timing is too retarded. Eventually the IAC will drop back to zero, I'll readjust it to 850 RPM & 2-9%, and then watch it steadily climb again. All times are GMT-6. Going in the direction you did (higher) is going to reduce the acceleration fueling that the engine sees. Duration @.050 is 240 intake 246 exhaust with .574/.578 lift. The Sniper even has a feature that allows it to use the idle timing to control the idle speed. That is what I really respect about Holley. 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. The engine has 14: 1 compression ratio, we can not use gasoline. Thanks for the info Chris. I am at the point where I almost insist that every Sniper EFI System owner purchase one of these. 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 hope everyone enjoys this v. Any suggestions? :-). Even at 0% it's sucking a bunch of air through the IAC port. back upthe RPMs shoot up to anywhere between 1500 and 2000 and they will not get However, I have never found that to be the case. (Note: in the original version of this post we had a section about checking the idle speed curve setting. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. 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. I was looking at a data log from my truck earlier this week and noted that at idle my IAC was zero. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. I've been having problems with my sniper efi just shutting off. I figured out I was going the wrong direction when I was messing with the AFR programming. 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. The latest was changing the power brake booster.Today I drove it to work and no issues at all. Your suggestion to remove the PCV valve is just for diagnosis purposes, right? 3 different fuel pumps. After much diagnosis, I ended up replacing the intake manifold gaskets. First thing I would check But another thing to consider is adjusting your target A/F ratio. I've tried repeatedly re-creating the scenario in hopes that the E.C.M. Relatively new Sniper EFI install on a '69 Mustang 302. The biggest issue is these problems are intermittent meaning they do not occur all the time. That is not something I'd ignore. I would suspect something is coming loose causing a stop to the EFI system/Fuel flow. The tps has slotted holes, can you adjust it to get to zero? Give us a hand! Repeat until that stumble goes away, and then try a bit more throttle. 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. 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. I know its not flooded because I can pour a little gas in the throttle body and play with the accelerator and it will start and run fine.