There is no sense proceeding until your TPS is at zero at key-on. 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. 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. 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. Shut off car/restart and it's back to idle at You can re-enable this after you have completed this idle speed adjustment process. I'm running a 408 sbc. 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. Or alternator? If you use your handheld to go here: I would start by datalogging the situation and seeing exactly what your learn table looks like in the area immediately around the tip-in. Take it a step at a time. 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. Watch videos on installation hints and if you haven't yet, download & read every Sniper installation guide you can find online. It started right up and we did your idle control fix and all is good at idle. I, too, wish you'd bought your Sniper from us! I have a set of 8.8 Accel Rfi suppression wires on it. any ideas? The engine ran so good, I would have never suspected the Fuel Pressure to be an That is what I really respect about Holley. When I am coming to a stop, the rpms will hang at 1200-1500 rpms. Holley Sniper Iac Delete With select intake manifolds, the distributor housing and IAC valve on the back of the Sniper EFI throttle body are fighting for the same . It is temperature dependent but 30 is commonly where you find it. around 45 mph it bogs down, catches itself, bogs, catches, bogs and catches. :-). Price Point: $$, Robust, feature-rich multi-port EFI systems offer easy plug-and-play late-model V8 engine swaps. Fought a high idle issue until I changed your idle speed curve fix along with dropping the IAC hold to 10%. Learning to install these is great--you're about to embark on the next great adventure of advanced troubleshooting. I recommend confirming there is no throttle linkage issue first. I'll bet you find that you can get it working great without any manual tuning. The first place my eyes go when there is any issue with the idle is to the TPS value. I did all of this before seeing the link you sent. No power at the programmer and no fuel pump running. :-) Just don't let the parts go flying. installing and cruising down the highway 70 mph I just wonder if all I have to do 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%. As I would slow down for a stop sign or stop light, the car would run really rough and the idle did not want to come down. When I see that your TPS is 1%, that tells me that you may have an RFI problem. During cruising at 30 miles and release the gas pedal the engine revs at aproximaly 1500 RPM and it won't drop. In your case, however, I think you're close to getting it running. Thanks Again for your help. It runs perfectly fine other wise. When I first told him to check for leaks he looked back there and said "all good". 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. Sniper EFI Idle Tuning. About two minutes after I get it set at 850 & 5%, it has progressed to 100%. Ive had an idle at neutral as high as 2400 rpm. Thank you for any advice. 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. They are prone to be inaccurate. 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. A problem since day 1 - YouTube Leave a comment if you've had this issue and how you resolved. Simply turn the idle speed screw on the linkage in until the throttle plates open enough for the idle to increase. The biggest issue is these problems are intermittent meaning they do not occur all the time. No big deal, just time to re-adjust! And thanks again for taking your time to answer these questions. The IAC reads 36 when at idle fully warmed up. I've been trying to correct that 1% small issue/annoyance. When you key on, you will hear three distinct sounds: The ECU initializing the IAC, the fuel pump priming, and the injectors firing their prime shot. That is the IAC hold position. I notice at 2-3% tps the iac is 18-25% and it stumbles, when the iac gets to my hold position of 30 it stops. I have been able to get it pretty Thanks again. Possibly cap, rotor, coil? It's a Chevy 350 bored .030" over it has a cam in it what I was told is the cam has the firing order swapped. I would gladly engage with you to solve this but ultimately you are going to need to go through whomever you purchased the system if a warranty return is in order. Can the return line be an issue?So far this sounds like an ideal setup.>I have had 2 faulty gpa-4 255 walbro pumps go bad. All of the wiring exits below the rear fuel injector cover, for a completely stealth installation. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. 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. Remember that as an EFI System Pro customer you have access to me at any time via my cell phone. Incorrect connections will result in excessive resistance. The headache is the Acceleration Enrichment. 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. It is working fine when you restart the car, controlling idle perfectly at 8 steps open so it is unlikely to fail when the car warms up--or correct itself instantly when you restart it..So, if you don't have any vacuum leak, and the throttle plates are fully closed, the only thing I can guess is something is causing your ignition timing to change. 680-700.I can't find any reason other than it looses where it is in the firmware with Resistance results in heat and heat results in more resistance. 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 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. If you have performed the adjustments above and still have RPM issues, it's time to look for clues. 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. School's out for spring break this week though so I'm covering for employees on vacation. Hello Chris. If your mixture is too rich, it means there's too much fuel and not enough air. Your AFR is pegged lean. It turns out that some of the Snipers are shipping with the minus 40-degree setting drastically lower, as shown in the following image. I set the AFR at 13.5 and all is good now. Several good bits here. I very pleased with the performance, it is a huge improvement from the 800CFM carb I had on this motor. 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 have a feeling it's something simple but I thought I'd ask you first before I inadvertently change something that affects other areas. If the TPS reading on your Sniper EFI System does not reset to zero that is a problem that needs to be addressed. Ive played with the timing on this thing multiple times.Car was fullly restored last year. That will happen occasionally, but less as time goes and on and the engine tune stabilizes. :-). I think that your timing is too retarded. 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. I then saw you guys have an awesome little gauge that can hookup inline to the snipers existing fuel feed?? 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 will at least tell you something. But there are several degrees of play there in which it should still work fine. 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. This item: Holley - 543-105 EFI Idle Air Control Motor , Black $71.72 Holley Sniper EFI 870001 Throttle Position Sensor $34.60 Holley 860004-1 92MM Sniper Throttle BDY $223.93 Customers who viewed this item also viewed Page 1 of 1 Start over Holley EFI Idle Air Control (Iac) Valve Motor 30 13 offers from $79.56 They always responded to my questions with guidance that helped me choose the right system for me. I ask because I'm using a PCV valve with my Sniper and have random idle issues as well. IAC Pos.% = 0 I'll have to check again tomorrow. While it is not mandatory, I recommend the Sniper EFI CAN-to-USB Adapter to move the data between your Sniper EFI and your PC rather than trying to do this via the SD card. I was 20 minutes into a drive yesterday when all of the sudden the RPM increased not commanded. There's still a very small amount of airflow that squeezes past a closed IAC valve; it's that venturi like sound you're hearing. I figured out I was going the wrong direction when I was messing with the AFR programming. I believe because the TPS is not registering. I have not heard of this. 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. Yes, having an accurate TPS is very important at idle. I've been messing around for a bit trying to eliminate any possible vacuum leaks. ps. Note too that the larger the throttle stab, the more brief the time in that cell and the more gradual the change.Here's what I recommend: Get somewhere where you can repeatedly stop and go. It would be possible to set up a 1D or 2D table and do something like this, so if you've gotten into these advanced setups then that would be another thing to check.If neither of these work then I'd recommend that you do a data log of the engine idling as the temperature is reaching and then exceeding 200 degrees. If you have any questions about the car/setup let me know. What could be the cause? other things that might cause the idle to faulter, but this is a good start. Use the idle speed screw to set the idle at a comfortable warm-up speed. Have you confirmed your fuel pressure at idle is 60 PSI? Im thinking a faulty TPS. This can cause the engine to run rough and may even lead to engine damage. May God's grace bless you in the Lord Jesus Christ. When you set the Static Timing to 15, what did you read with the timing light? So you installed your Holley Sniper. 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. I installed another return spring for the rear plates problem solved instantly. I go into much more detail about that in this article on startup tuning. Since a key cycle resets it to 0 and out to 30 or wherever 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. 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. What an amazing site you have here. is jumping all over the place when you experience this condition, it does not Hopefully replacing the pump again will resolve both issuesWhoa. I am extremely suspect of what you were told about the Sniper ECU monitoring fuel pressure, for several reasons. It will learn the fueling eventually either way, it's just that one might get you there a little faster.If the idle is fine at start-up but then increases after you depress the throttle then you might need to lower your IAC Hold Position a bit. 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. Once you have done this the challenge is to create a datalog that includes the ":snap" you describe. Definitely would have went with you guys. Tps is saying 26% when it at idle. The first thing I'd do is check your fuel pressure with a gauge like this. The 10 step set up on your page set my idle perfect and iac perfect a very consitant 700. I have a Holley Sniper EFI with HyperSpark ignition. Duty Cycle% = 3 The throttle blade adjustment is at 2-6% at hot idle, and with warm engine 185F. If you datalog the Sniper ECU and see multiple overlapping traces for the same signal, you likely have RF-induced problems. $107.95. I have changed my roc/tps to 7 from 15 but that only took me out of learn mode. 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. 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. carburetor setup, but it does blow when I can't jump on the highway like I use Sniper EFI offers superior throttle response and wide-open throttle power. It has a lightweight centrifugal spring kit installed so I reach total timing around 2500 rpm. 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. Check the Distributor Tach Connection to the EFI. Get a solid feeling for where it is when the engine is warm and the idle speed is correct. Have you ever experienced a high idle once the engine reaches 200 degrees?Ive set my idle the way you said and it works great until the engine reaches 200 degrees. 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. It could be that you've left a vacuum port unplugged, it could be that the throttle plates are misaligned (unlikely), it could be that your IAC is not closing properly. Ok, we have enough Sniper systems out there that I thought it would be a good idea to create a posting on challenges that might arise during installation. THANK YOU for the "First--Check Your Idle Speed Curve Setting!" The IAC is hanging open and not really at 0. I will try the other stuff when I get off work. Hi Chris, I have a lean stumble on throttle tip in 2-3% tps taking off from a stop light the afr will go to 19afr and the engine will stumble for a split second. The person I bought it from said he never could get it to run for more than a few seconds. If I cruise down the road at lets say 60 mph and lay into it, she will take off and go. One thing you need to sync the timing and set the inductive delay. It appears that I could now use the dongle and a laptop to custom tune for idle issues if needed. This page was generated at 12:26 AM. You may have to register before you can post: click the register link above to proceed. I've helped folks work through a number of challenges with their Sniper EFI System installations. Next, clean the IAC and all related parts with brake cleaner. Yes, let me know how that setup process works. I'm going to jump out on a limb here and say you either don't have adequate fuel flow or pressure. Just wondered if you've ever run across a system not powering up? Try it! So, clearly, the "No" answer is wrong. If the IAC number is increased during this high idle, review the points about high idle from tuning issues. The very first thing I would do is get ground truth on your timing. IAC percentage is 5 to 10% when idling with fans on, What you're experiencing is the delay time between the ECU sensing the additional load and the IAC actually increasing the RPM. Chris's Idle Speed Adjustment Instructions*: *Note: If you are using your Sniper to control ignition timing then I recommend that before you start this process you disable idle spark control If you are trying to do this while the ECU is simultaneously trying to bring your idle under control by adjusting the advance it is going to be counter-productive. In this short video you learn to replace the IAC. Since that has long been corrected we have moved that information to the bottom of the article.). Chris thank you for the info. By the time I was near home, the idle in Park was 1050, IAC 0. 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. However, I have never found that to be the case. After pumping the pedal a few times at different times it dropped to zero and started to work. When I covered the IAC with my finger, the RPM dropped so low it stalled. That is the first thing you must find. The Sniper EFI replacement throttle body for Autolite 1100 carburetors will be right at home on most early in-line 6 cylinder powered grocery getters or weekend cruisers. Super helpful and knowledgeable. 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. 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. Fuel Prime Multiplier is primarily a benefit to throttle-body based EFI systems. We've already tried adjusting the Acceleration Enrichment chart in all ways, going up and down, RoC Blanking, everything, it has no effect. Then Friday night as I was driving home, the car started acting up. Kind of cuts into forum time. That, on top of your air leak, is allowing the engine to idle at 2400 RPM. I tried adjusting my IAC up to 10deg in both directions with no change. Confirm the placement of all wiring, ensure that the WBO2 sensor is positioned properly, etc. The fix? I have now determined with the TPS the noise correlates with the opening of the secondary butterflies. There are two ways to address this--you can let the system learn or you can manually adjust the acceleration enrichment. :-). Thanks for your very detailed question! 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. However, whenever you start changing things, you can get into a chain reaction. Throttle Tip-In puts you in a part of the fuel map where you stay for only milliseconds at a time. Should it not do the opposite and do this on a cold start not warm. Thanks. Start engine let it warm up to 160, learn mode is learning. After much diagnosis, I ended up replacing the intake manifold gaskets. Thank you in advance for your help and providing us rookies with your When I put it in gear, it drops so low that it will stall if I don't add throttle.