I am at the point where I almost insist that every Sniper EFI System owner purchase one of these. 90% of problems, (INCLUDING MYSELF) could be answered/fixed by just reading the instructions. Commanding the engine to automatically increase speed when switching into drive is a little scary to me though. TPS 0. Thanks so much for reading! Intermittent stalling usually points to radio frequency or electro-magnetic intereference (RFI/EMI). If you have any questions about the car/setup let me know. I followed the instructions and set the IAC to 2-9% when warm with idle at 850 RPM. Running the vacuum advance and of course I time it disconnected. It starts cold fine, its just when its hot. 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. But another thing to consider is adjusting your target A/F ratio. If I were there in person I would test the function of the IAC (see this article.) Anyway I have a 327 sbc in a 1987 Monte SS with a T5 5 speed and 3:73 posi rear. You may have to register before you can post: click the register link above to proceed. The person I bought it from said he never could get it to run for more than a few seconds. Cycle the ignition as instructed by the handheld and then navigate to the distributor setup screen. Please help. All times are GMT-6. any advise would be appreciated. For the first couple of drives it was running well, Sniper EFI was working exactly as advertised. That initial rev is going to be determined by your IAC Park Position. At that point, with 90 PSI of fuel, the ECU can't turn the duty cycle down low enough to idle properly. Please let us know how this works out for you! 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. 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.) Be aware that there is a spring behind there and a diaphragm that you don't want to tear. Hey Chris! Capability Range: Moderate The only way to confirm RFI problems is by doing a data log. If I block off the iac with tape , I can get it to somewhat idle, but its not consistent. That is not the way to go. 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. Only show this user . 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. Genuine Walbro fuel pumps are virtually bullet-proof. The IAC is hanging open and not really at 0. I've abbreviated it just a little bit but am appreciative of the added insight your comments provided.Off-idle performance can really be a challenge to self-learn but be assured that it can almost always be done. Once we recognize that, the next step is to narrow down all possible sources of additional air until we discover the cause.Start by keeping an eye on your IAC number. 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. Yes, it will talk to you--but not with words. I'd suggest that you assume everything the previous owner did was wrong until you can prove that it was done correctly. I think you will find that it will learn its way through this. 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 Does this seem reasonable and how hard will it be to get the idle and off-idle performance correct? 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? Stupid question, but where do I see if it's entering Learn mode? A question I cannot get a 100% answer on is can you piggy back off the Sniper EFI TPS for an electronic transmission? Then it will ramp down to 1200 but will not return to idle. That's not the IAC Hold Position, it's a percentage value. I have certainly seen this before on other fuel injected vehicles when hot. :-). Your second problem should be a bit more concerning. I have been reading these posts and have learned a lot. I did change the -40 thing also. 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. I hold my foot steady in place it does this in 5 second cycles and if i let go of Now it's at 5% on a big cam 440 Mopar. An under-sized filter will allow part- throttle operation but fuel pressure will drop at WOT and run very lean - perhaps surge under power. P.S. Thank you for your input. These are "transitional" cells, and you really have to make the effort to learn in these areas of the map. That is the only way to fly. I'll give the ". Seems to behave more better now. It started right up and we did your idle control fix and all is good at idle. = 2.34 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. I appreciate everything you are saying. No power at the programmer and no fuel pump running. This curve turns the idle speed down as the engine warms. Wish I had bought my sniper from you, but unfortunately didnt. Capability Range: Advanced 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. 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). Thanks for the great question! )Take a look at your AFR during the starting process. But after sitting static idling for a little bit, the IAC goes to 100% & stays there. At 0% it shouldn't be sucking any air through that port, correct? 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. Thanks for your very detailed question! After much diagnosis, I ended up replacing the intake manifold gaskets. If you have a bellcrank in your throttle linkage, ensure that the linkage is not engaging the bellcrank at an angle greater than 45 degrees at either end of the throw. This page was generated at 12:26 AM. I certainly appreciate your frustration (as well as your wife's!) Good I appreciate the help youve given to everyone as it continually helps me! The latest was changing the power brake booster.Today I drove it to work and no issues at all. Ive tried setting the prime setting above 150 but it wont take, it always goes back to 150. Took it for a lap around the block and came back. 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. I have been able to get it pretty 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. Do you have a PCV on the engine? 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. That is what I really respect about Holley. Thanks. I looking for your expert opinion. Get a solid feeling for where it is when the engine is warm and the idle speed is correct. It is always best to get the base map as close as possible before adding acceleration enrichment. We'll also be contacting you for future purchases now that I've discovered you! Well, it sounds to me like your Sniper is doing its best to reduce your idle. By going into the IAC settings and turning off the Idle Spark control and setting Target Idle to 750 RPM my idle issues are gone, and it now returns to desired idle after cruise. :-). In the datalog the engine is running at 1400 RPM, TPS is zero, IAC is zero, CTS is 185F but it's in Open Loop. It didnt do this with the carb on it. Advanced throttle body injection systems capable of transmission control and more. Tried that and it didn't work? Copyright 2022 Holley Performance Products, Inc. All right reserved. Do please let us know what you find out! I have driven it a few times maybe 100 miles or so. If not then I think you are going to find that this will solve much of your problem. Just add 5 or 10 degrees of advance and see if it doesn't idle better. >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. One of the most common symptoms of a Holley Sniper EFI problem is an air/fuel mixture that's too rich or too lean. This is actually more troubling than the sound you originally described. Either the Walbro pumps you are getting are not genuine (lots of forgeries being sold) or else you have something that is killing them. Fortunately, I have an article that goes into this in some detail. It turns out that some of the Snipers are shipping with the minus 40-degree setting drastically lower, as shown in the following image. When I turn it off and try to restart it just cranks. :-). If you do find you have RFI issues then I've written an . Copyright 2022 Holley Performance Products, Inc. All right reserved. Yes, the sound coming out of your Sniper throttle body is a pulsation from the fuel pump that is pulsing the mechanical fuel pressure regulator. View Holley Sniper EFI Self-Tuning Kit - Shiny Finish. Yes it is controlling the timing and I had issues at first and it controlled the idle just fine. To finish, I rather tightly twisted the TPS signal and ground wires all the way from the controller to the Sniper TPS and very carefully routed them away from sources of RFI. I know this is old, but I bought and installed a Sniper kit in 9/18. Very annoying ended up being simple my rear plates would stay open constantly it was driving me nuts I'd let off the pedal idle at 1300 blip the throttle a few times finally come back to 850. Note that sometimes you can get into a back-and-forth situation. Somehow air is entering the engine that was not entering the engine when you originally set the idle speed screw. Rpm with 4-8 iac but it still shows red and shuts off randomly at idle and it won't even drive 2 miles without shutting off. 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 was looking at a data log from my truck earlier this week and noted that at idle my IAC was zero. Save Share. installing and cruising down the highway 70 mph I just wonder if all I have to do Your suggestion to remove the PCV valve is just for diagnosis purposes, right? Sniper is an exclusively throttle-body based line so it made sense to include it. In the time it takes to add your email address you can be at the top of the heap for getting the latest information from our authority. Hot start it most of the time wont start unless I give it a little throttle. If you use your handheld to go here: I used the Casper's Electronics 108103 splitter and carefully soldered my connections. So, if pressing the throttle is making it start, it's because you're flooded.Which is consistent with your rich idle condition comment, right? Enjoy! I'm going to jump out on a limb here and say you either don't have adequate fuel flow or pressure. Fuel Flow lb / h = 12.1 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 It sounds a little different from mine, since it commands a 1300 or so increase intermittently. The throttle plates are misaligned. Will restart but only for a minute or so a couple of times then shuts down fuel delivery and will not restart. I received from the controller manufacturer greatly understates (at best) the repeated failures of others I know personally who have tried and failed. Yes its at 95lbs, needless to say he promised a new regulator would be in the But I think it is safe to say that you are now at a point were some manual tuning is a good idea. A problem since day 1 - YouTube Leave a comment if you've had this issue and how you resolved. 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. I would start by datalogging the situation and seeing exactly what your learn table looks like in the area immediately around the tip-in.
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