One of them might be faulty. The symptoms I had was a low cold start idle and going lean coming to a stop. Holley will take a look and tell you you have RFI and wish you good luck in finding it. and when I close the IAC's hole with his finger, the engine is normal.The data on the touch screen I see are:AFR, A / F = 35.6 Confirm the placement of all wiring, ensure that the WBO2 sensor is positioned properly, etc. I don't want to go on too long here but once you know if you're trying to add or remove fuel, there are a couple of ways to go. Then your low idle problem will go away. When this occurs, I sometimes can shut it down and it will return to the correct settiings. i'm having is I can't seem to get the truck to run faster than 45 mph at speeds 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. Given the circumstances I would say that it is either the IAC motor itself or RFI but you seem to have ruled both of those out. If it is then something is commanding the ECU to open the IAC. To be honest, you sound like an ideal candidate for Sniper ECU ignition timing control. I installed the Holley Sniper in my Chevelle this winter with a brand new BluePrint 496. No air should be able to pass. Ive tried setting the prime setting above 150 but it wont take, it always goes back to 150. Are these compatible enough? We're having trouble with a Ford Maverick 302 V8, using ethanol. Once engine is warmed up been driving for awhile. The Sniper EFI system looks at the closed-loop fuel compensation required to reach your target AFR. But as you see from the recent revision I did above you seem to be having a fixable issue. I went on the good ole interweb and found your website which was VERY helpful! It then started working normally again. The last 2 times have been shorter and one time the high idle was around 1400, this time around 1100. Sniper EFI Idle Tuning - Holley Motor Life Thank you for your input. Stupid question, but where do I see if it's entering Learn mode? Resistance results in heat and heat results in more resistance. Technically it is a warranty-voiding maneuver so proceed at your own risk. I readjusted my IAC, now it's perfect. The tps has slotted holes, can you adjust it to get to zero? Is this normal ? If no air is passing (and the idle doesn't drop) then your IAC is working. Fortunately, I have an article that goes into this in some detail. However, I can't think of a single one that was because of low vacuum. If you go the other way then you might find that the IAC zero's out when the fans are off. Ok, so I'm stumped! The latest was changing the power brake booster.Today I drove it to work and no issues at all. You might have a bad O2 sensor, really bad exhaust leak or a problem with the ECU. I received from the controller manufacturer greatly understates (at best) the repeated failures of others I know personally who have tried and failed. Contact whomever sold you your system or Holley directly. Ensure all your sensors are displaying proper values. 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 Thanks. I guess we can't have everything. 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. Both Sniper and trans controller grounds were direct to the battery ground, as they should be. It sounds a little different from mine, since it commands a 1300 or so increase intermittently. The team at Holley has designed the perfect solution for your problems. Engine warms up to 195 degrees and stays. There's nothing wrong with manual tuning, but at this point that is just compensating for an inadequate fuel map. Having a TPS that won't go lower than 9% will affect the acceleration enrichment correction, and could create a stumble at the first moment of throttle opening.Yes, the IAC can and will fluctuate depending on changing conditions. holley efi. View Holley Sniper EFI Self-Tuning Kit - Shiny Finish. back to trying to zero down an idle. During cruising at 30 miles and release the gas pedal the engine revs at aproximaly 1500 RPM and it won't drop. But they are 100% committed to your satisfaction. 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. Properly configured, the Sniper does a fantastic job of responding to the transition from Park to Drive. I have replaced the IAC motor and the problem remains. 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. This is more of a bit of a reality check. It is how the engineers allow you to clear a flood condition when you detect it. The fuel pressure regulator in the Sniper is fairly simple and not prone to failure, as far as I know. 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. That will at least tell you something. 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. It drops about 200rpm when clutch engages. Sniper EFI Initial Startup and Troubleshooting Staff Writer 01/20/2020 Could the IAC be broken/malfunctioning? Even at 0% it's sucking a bunch of air through the IAC port. At some point you come upon problems that evade the easy answers and this is a good example. Mechanical Fuel Pressure Gauge on the inlet of your Sniper, now is the time. Should it not do the opposite and do this on a cold start not warm. After a stall the car will restart but will be in a high idle. If I try and get the 2-10% i get all the way up to 1200 rpm. Turning it off and back on would reset it, and then it would work as advertised for a while. Thanks for sharing that, Jason--great info! The Fuel Base map is perfect, the car works well, runs well, running through the streets, the car is great. My guess is a faulty IAC since it is intermittent and I have not done any setup changes. If the solutions suggested above are not working then you need to review my article on IAC Testing Procedures. It is temperature dependent but 30 is commonly where you find it. That, on top of your air leak, is allowing the engine to idle at 2400 RPM. 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. And since they really had an insanely-tight monetary and real estate budget in the Sniper EFI System, it is unlikely that the added something that wasn't absolutely necessary--and then forgot to use it..And you are spot on about the little Earl's gauge with optional -6 AN port. Or ?I have put a fuel pressure gauge right at the inlet of the sniper and it is reading 60-64 psi. I have tried your 10-step idle adjust and ive adjusted the idle curve. :-). A problem since day 1 - YouTube Leave a comment if you've had this issue and how you resolved. By the way, this is a new installation on a 69 Camaro, stock 350, dual sync, etc. Your AFR is pegged lean. normal city driving, I no longer have other problems I had with the original And your question is very perceptive: You must first know whether the bog is a lean or a rich condition before you can make the correct adjustments. I keep doing that with the same result. Enjoy! If i set the idle to 750, the only way i can get it there is to turn the idle screw all the way out but then its at 0 iac. And Earl's makes a fantastic little 100 PSI gauge. I tried adjusting my IAC up to 10deg in both directions with no change. (Grease can sometimes do the same thing as a more permanent gasket sealer without making the removal of the air cleaner such a pain.). Its just at low speeds, not sure if its loading up or leaning out. Why is this? hard start about 1/2 throttle from stop it bogs down after 3 or 4 seconds.What I Sniper EFI Tuning & Tech. The idle is 1350-1400 with the idle screw at initial contact. Make sure that your blanking level is _below_ that (being careful not to find yourself in the situation I describe above.) You are aware of the idle-up problem. These problems will go away when you do that. I started with right after I first adjusted for 2% IAC and took pics about every 30 seconds over about 2 minutes. 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. FYI: Car is a 1970 Mustang 302 Ford Racing roller motor. Shutoff engine wait 30 seconds, turn key wait for display to come up, start engine. Going in the direction you did (higher) is going to reduce the acceleration fueling that the engine sees. I would continue checking the electrical connections along the fuel supply. Take a drive and stop somewhere for 30 minutes, CTS is 170 when engine was shutoff. Took it for a lap around the block and came back. Relatively new Sniper EFI install on a '69 Mustang 302. Tps is saying 26% when it at idle. 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. Hang in there--you can do it. Relatively new Sniper EFI install on a '69 Mustang 302. Holley Sniper EFI Troubleshooting Mudford Garage 8.6K subscribers 38K views 3 years ago My Bronco with Holley Sniper EFI was running poorly. I followed the instructions and set the IAC to 2-9% when warm with idle at 850 RPM. I have seen this become blocked with debris / dirt in the fuel system and cause a high fuel pressure condition . Do you have a PCV on the engine? So check that timing and I think that you're going to find you need a good bit of advance. I think that the more important point is that Holley kept sending him units until everything was working. other things that might cause the idle to faulter, but this is a good start. I had this same exact issue. Key, I believe, in this success is solid connections, resistance-free signal and ground paths, and solid RFI rejection. I am right back to where I started. Either the Walbro pumps you are getting are not genuine (lots of forgeries being sold) or else you have something that is killing them. Please check your process again and see if you can see very specifically what is not working correctly. The broad consensus has been that the Sniper is an amazingly straight-forward install and starts and tunes as expected. So you installed your Holley Sniper. It's not necessary to drive it that way. It didnt do this with the carb on it. Any idea's? The fact that it ran so (at times) with 90+ PSI fuel pressure is a testimony to the Holley's closed-loop technology. I'll bet you find that you can get it working great without any manual tuning. If you can track specific engine coolant temperatures where the engine stumbles and dies that would be a good place to start. In your case, however, I think you're close to getting it running. Price Point: $$, EFI Systems based on Holley's world-class Dominator and HP ECU's. mail today. I have a feeling it's something simple but I thought I'd ask you first before I inadvertently change something that affects other areas. We offer some tips to help with that. I did buy the Sniper from you guys and the service was fantastic. check out the. When I turn the key on I can hear it prime, but I don't think im getting enough fuel. Jump on board now! I thought 12.0 was leaner at idle, but I figured out I was wrong.lol. I've been trying to correct that 1% small issue/annoyance. Thank you for any advice. Do please let us know what you find out! There are six different acceleration enrichment tables that you can tweak and that may be the way to go. Remove the tape from the IAC breather hole and restart the engine. Start with the most gradual throttle input you need to launch well, then slightly increase until you feel some stumble. Copyright 2022 Holley Performance Products, Inc. All right reserved. Two months fighting, cursing, not getting any help from Holley OR the forum, and a stupid little tin plate. That's a nice change of pace--a low idle issue! 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. Next, reach down into the secondaries and push the butterflies closed. The only way to confirm RFI problems is by doing a data log. This is normally used as an A/C idle-up circuit. 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. After speaking with Holley Tech Support and Tech Support from where I purchased the systemthey decided to replace it. 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. A couple of those and you should feel it getting better. Thanks for any help. Ive had an idle at neutral as high as 2400 rpm. One of the signs of a vehicle with a rough idle is a faulty Idle Air Control (IAC) Motor. Is there away to program the ecu to compensate for this at start up. The first place my eyes go when there is any issue with the idle is to the TPS value. When you open your IAC to 30% you are naturally going to have a high idle condition. But I am having troubles.When stepping on the accelerator slightly with idling, it will be 2000 RPM all the time. NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160F! This can cause the engine to run rough and may even lead to engine damage. If that tested out okay then I can really guess that there might be some sort of intermittent, temporary RFI. I have a 406SBC that does most everything right with this sniper setup. Interesting question. 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. THANK YOU for the "First--Check Your Idle Speed Curve Setting!" First, check to make sure that the IAC is properly mounted and connected. 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. Plus, you can email that file to me and I can be of more help. The IAC reads 36 when at idle fully warmed up. Kind of cuts into forum time. You can disable the idle spark control at the locations below. Fortunately, these are much easier to solve. To get it to idle the tps is at 2-3-4% even with linkage disconnected and a return spring installed. Hello Do you have any clue? I recommend confirming there is no throttle linkage issue first. :-)Yes, learn impacts idle too, and remember the even when the basic learning is done there will continue to be some learning for changes in weather, altitude, etc.Go ahead and try a few idle settings and see how they impact the idle-speed searching. So try changing your IAC hold value slightly:Tuning : Advanced : Adv. Capability Range: Advanced 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. 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. I've changed all the I have not heard of this. Thanks for the info Chris. What should I be looking at to calm this down? Get On The List for Emails Straight From Our Pro? I had a customer recently with a high idle problem that he eventually traced to pad plug on one of the vacuum ports. This increased idle speed is triggered by grounding the orange wire in the 10-pin I/O harness. installing and cruising down the highway 70 mph I just wonder if all I have to do My primary reason for going EFI was drive-ability, (Startup and take off without waiting for the engine to warm up) and not have the occasional hesitation a carburetor has especially just barely opening the secondaries. There is no real mystery here. Hi Chris I didn't get any traction on Holley.com And, while that is happening, make a note of the temperature before you engage the starter, and then the rpm when it starts.The Idle Parked Position is set on a temperature-based graph like the Idle Speed Curve. I did all of this before seeing the link you sent. Using a Snap-on variable timing light so this is why I say timing is perfect. Ive played with the timing on this thing multiple times.Car was fullly restored last year. This is actually more troubling than the sound you originally described. the issue To keep it running in gear, I have to bump the neutral idle up just over 1000 RPM. 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. The tps will not auto reset to zero. The problem was RF interferance . 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. Camshaft is M-6250-B303 .480 lift intake & exhaust, duration at .050 is 224 degrees for intake & exhaust. When stopping, the brakes are unable to overcome the engine so I go to neutral just to stop fighting the engine. Initial Baseline Idle Speed Screw Setting, http://forums.holley.com/showthread.neral-IAC-Info, http://documents.holley.com/199r11031r.pdf, https://forums.holley.com/showthread-Idle-Solution, If this is your first visit, be sure to 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. In the setup, I set the hot idle for 850. 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. 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 is the only way to fly. The biggest issue is these problems are intermittent meaning they do not occur all the time. is the fuel pressure. issue. The solution is to either lower the IAC hold position or increase the RPM above idle to start ramp (default is 1000 RPM). Your suggestion to remove the PCV valve is just for diagnosis purposes, right? 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. On a cold start it will idle at 750 everytime, But if its hot start it will jump upto 1600rpm for 2 seconds then come back to 750. 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. Again, I would lean on that solution to let the vehicle drive/learn before you try to "fix" anything. But if you can datalog the bog you can know much more precisely what is happening. Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. When I put it in park the idle RPM was 2100-2200 each time. 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. Not good.There isn't set solution here that works for all engines. When you experience this, before you touch anything or shut the engine down, first look at your TPS and your IAC. 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 is a chance that the IAC is open but displaying 0% so start by putting your finger over the IAC opening. My car will not idle right until it gets to around 130 -140 degrees. 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. If you go too low then it may stumble or even stall when coming off of throttle. It felt like it was flooding out at low speed, low. )Since this isn't a consistent issue with all Snipers that tells me that different IAC settings tend to make the whistle. Holley Motor Life You might have a bad IAC, but you can also have a bad vacuum pod on the transmission. Um, no. I did read some comments on regulator issues is there a way to check it for an issue ? Eventually the IAC will drop back to zero, I'll readjust it to 850 RPM & 2-9%, and then watch it steadily climb again. Is that normal? If you did not rotate the distributor to set the actual timing to 15 that might be the only issue. You might even want to add our 4-foot extension harness that will allow you to connect/disconnect the display or CAN-to-USB adapter from inside the car (rather than trying to do that leaning over the engine and under the breather. If idle drops below 800 it wont come back itll chug around 300 rpm for a few seconds then die. This value is itself enough to raise the idle a bit. I've read that a spacer with 4 individual holes will solve this, but after I installed the progressive linkage the noise went away!! I will try the other stuff when I get off work. I'm running a 408 sbc. I also noted that after some time, I could change those values as I saw fit. Now it's at 5% on a big cam 440 Mopar. Sometimes an engine can produce enough vacuum to pull the secondaries open slightly. I would suggest you take a look at that if you haven't already. The weather in Ct has finally improved and I have put about 60 miles on the car with the Sniper system. I've helped folks work through a number of challenges with their Sniper EFI System installations. Copyright 2022 Holley Performance Products, Inc. All right reserved. IAC Pos.% = 0 I installed another return spring for the rear plates problem solved instantly. Is this an issue to worry about? If your TPS is at zero and your IAC is at some random number above 8% (but not exactly 30%) then for some reason your engine has not met the conditions to ramp down to target idle. 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. Tuning > Advanced > Adv Idle > IAC Startup What I would recommend is getting somewhere that you can spend a significant amount of time doing starts. 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. to. I was shocked to see it at 95lbs!! How to replace the IAC in the Holley Super Sniper. - YouTube 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 you rule out a fuel supply issue then we're going to have to gather a few more clues. 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. I recently had IAC issues identical to what you describe. 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. The learn percentage should gradually decrease to virtually nothing as the map plus learn table begin to get more and more accurate to your specific setup. This will go a long way to improving your fuel map without manually adjusting the acceleration enrichment. Therefore The iac will always be at 10% now, correct? Thanks for your very detailed question! I was looking at a data log from my truck earlier this week and noted that at idle my IAC was zero. If you haven't installed a 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. I believe that you have this problem solved now with your new inline filter/regulator. Though it started and ran good, it was dumping fuel and would not lean out to AFR set points. This is a mighty big subject for a blog post reply, I should probably start doing some videos on this. 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. Thanks. I think you will find that it will learn its way through this. Sniper EFI - Holley