Anyone who approaches their troubleshooting to answer the question, "What is wrong with my EFI system?" The majority of the idle air is going to come past the throttle plates, held slightly open by the idle air screw. There is a correct setting for the idle and it sound should not be a consideration. Get a gauge. Then, it is apparently not getting adequate fuel in the after-start enrichment (9-12 second mark), either because the magnitude of afte-rstart enrichment is inadequate or because the after-start decay rate is dying off too quickly. Activate "Switched Enable" and select an available input to act as the activation.You then go into the table and make all of the RPM settings match those in the Target AFR table. In fact, MOST of the points on the fuse block don't do that! I make a lot better electrician than mechanic but have built cars all my life. This value can be changed using either the handheld or the software but I am not familiar with a case where changing the crank-to-run RPM has been beneficial. Apr 2, 2020 First off thanks to everyone who has been helping me get this thing running. If you free dumped it in the top, it will aerate and foam up the fuel. For the Sniper it is best to run resistor plugs. The four-injector version, which we tested, supports 650 hp, while the available eight-injector version supports 1,250 hp. When a wide band sensor is (DAMAGED) it almost always reads dead lean. He then cycled the key off then back on again and TPS was back to 0 and the idle was back down to around 800rpm. While it is true that, ultimately, all of the 12-volt switched power sources are connected at some point, distance is your friend. I need to get an answer to the question concerning the TPS. But as you go farther back, it only gets better. Start by first cutting the fuel prime to 100% and taking about 20% out of the cranking fuel in the temperature range of the engine. Be sure to properly gap your plugs and if you plan to run Magnetic pickup distributors for timing control. Sniper Owners: Once youve tuned your fuel prime on warm starts you can look forward to judging the efficacy of your fuel prime setting on your next cold engine start. Need to add fuel pump for required pressure. Will going further help more? Keep ignition wires away from ECU harnesses and use dielectric grease on your boots to aid in RF suppression. All seemed well with the setup and going through the handheld. Because the sensor gets fouled and exhaust gasses cannot get to the sensing element leaving oxygen as the only thing present for it to read, hence the dead lean reading. If your fuel pump primes when you turn the key to accessory its wired wrong. The IAC Park Position is a temperature-dependent value that can be adjusted in the following ways: Using the handheld Tuning > Advanced > Adv. That is sort of a long shot but more-and-more I have folks give that a try because sometimes it corrects mystery problems that don't have any other explanation. O2 Sensor Mounting: The O2 needs to be mounted 6-8 after the merge in the header collector.Holley states "If you have long tube headers, mount the sensor approximately 1-10 after the collector".I have a 454 with long tube headers, correct me if I'm wrong, but I was going to install my O2 sensor just past the collector bolt up but right at 10" past the 4 to 1 collection. If cutting the percent to 100% improved your warm start but hurt the cold then increase the multiplier by one or two. And that from a not-so-shabby original 1.13-second start time. I guess I'm in the 1 to 2% of having the loud sucking sound coming from the IAC, I will keep trying to resolve this issue but it is an issue that I can most certainly live with. In a nutshell, you do the following:1. Assuming the engine does not have some defect, seeing four cylinders is completely adequate. Ill check the coil and see if anything else is attached. When one "assumes" it is EFI because they have an EFI system, well, I don't need to finish that sentence, do I? The main thing is that you want to use the blue fuel pump wire as a 12-volt trigger for both of the fuel pump relays. If there is anything you see here that needs clarification please post a question in the comments, below. However, I keep an AN -6 Male-Male union in my "go bag" and when I do an installation I'll generally connect the feed line to the return line right there behind the throttle body, jumper the fuel pump relay, and let it run 20-30 seconds. Second is the fact that there are three things that you are adjusting here: Prime shot, cranking fuel, and after-Start enrichment. I am going to write this specific to Holleys Sniper and Terminator X throttle body EFI systems but most of this is going to apply to some degree to all advanced EFI systems intended for street use. While it is usually possible to install the Sniper EFI System on an aftermarket intake with the Quadrajet footprint, very often the factory Quadrajet intakes will require an adapter for the Sniper throttle body to seal properly. You do have a fuel pressure gauge, right? Therefor, -40 + 100 degrees = 60 degrees. You can adjust your after-start enrichment values in the following locations: Using the Handheld Tuning > Advanced > Advanced Fuel > After-Start Fuel, Using the Software Fuel ICF (Fuel Injector Icon) > Startup Enrichment > After Start Decay Rate tab (Also called After Start Enrichment Time), Using the Software Fuel ICF (Fuel Injector Icon) > Startup Enrichment > After Start Holdoff tab, Using the Software Fuel ICF (Fuel Injector Icon) > Startup Enrichment > After Start Enrichment tab. That helped. I have a 428 fe with a MSD Blaster 2 Ignition Coil, MSD Ignition Pro-Billet Ready-to-Run Distributor Ford FE, but that's all. I really would like to replace the intake gaskets. So now youre left with tuning the Fuel Prime Multiplier. Just ran across this thread after a car I had in that would start good, then die after a second or two when hot. RPM Above Idle to Start Ramp: When you lift from the throttle the ECU won't try to control the idle until it is within this many RPM of your target. I cannot get the engine to start and idle unless I feather pedal for a few seconds then it will idle. I have purchased two sniper EFI with the MSD distributor kit. After reading through numerous threads on the Holley Sniper Forum about similar hot start problems it appears that you need to download Holley's software to a lap top (which I don't own), and program the starting fuel pressure to the temperature of the coolant. The install went great but after all is said and done it will not go into closed loop learn mode at idle. Advanced throttle body injection systems capable of transmission control and more. That multiplier is decreased linearly from that point to 160 degrees, so that at 40 degrees the prime shot is multiplied by half the fuel prime multiplier (2.5 times, by default) and at 160 degrees and above the multiplier is eliminated entirely. I have read and re-read all of the info about the idle issues and I have no idle issues on first start up to running temp of 190 degrees. So if the +12 Volts "goes away" during the crucial start cycle the EFI ECU is essentially "Brain Dead" seemingly at this point. Some good info here thank you. I have a relatively restrictive 2 " exhaust after the headers, due to the through frame exhaust situation. Do you have fuel pressure? You mentioned its use in # 9 of the top 10 Sniper EFI installation tips. The fuel pump should turn off after 5 seconds until the motor is started. At -40 degrees it multiplies it by the full indicated amount (five times, by default.) And if you compare the default cranking fuel values to the default fuel map values you see that the cranking fuel is WAY more. Copyright 2017 Cyberspace Automotive Performance, Inc. All Rights Reserved. Too little opening and the engine risks not having enough air to start. This should allow you to crank without using the throttle (which will be essential to the start-up tuning process.). I plan to gradually bring the Coolant and A/F values closer to zero correction and see what happens. First, there is the obvious--the system has to learn. Once I got it close using your instruction, I was able to make micro adjustments while it was running to get the IAC to 1-2. Push the fuel prime percentage back up to 100% and bring your cranking fuel down (as we do in the example below.). Can I run the pink ignition wire to the coil positive? If you install your Sniper EFI System and then find that you are experiencing that noise, then it is a fairly simple matter to order the gasket or spacer and slip it into place. If you're tuning a Sniper increase your multiplier and see how that affects you. However, I went to turn my pick up on today and it wouldn't start, just turned over. FAIL!! I am in the middle of plumbing my new sniper throttle body system. Great job implementing what I've written! Lets try 75% on the fuel prime. Thanks! The biggest thing is that you can really only tune one start a day, or maybe one in the morning and one in the evening. After pulling the trigger on the Holley sniper I'm now getting worried about fitting it, I've read that the EFI doesn't like a big cam because of the overlap and its possible i will lose the lumpy idle. Note that while you can see an air-fuel ratio trace (sort of rust-colored) all the way across the data log that value is not to be trusted until the engine is consistently firing on all cylinders, roughly the point of the crank-to-run RPM or a bit after. Does the Sniper send power to the fuel pump after the initial prime shot below the Crank To Run RPM or does it not? Chevy 350, rocker cam, mild cam. Runs, then dies. I have just finished installing my Holley Sniper to my 67 Camaro. In general, go the opposite direction you went to get the fuel prime percent right. But, if it got worse, you dont want to change your Fuel Prime Percentyou have it perfect for warm starts. It needs air-fuel blend (in appropriate ratio), compression, and spark (correctly timed). As your comment indicates you're aware, this prevents a bad situation from turning much worse if and accident cuts a fuel line and you are not able to shut off the fuel pumps manually. Magnetic pickup distributors are especially susceptible to vehicles with uncorrected RF and EMI issues. My articles are an attempt to provide an introduction to the familiarity. One of the most common causes of poor idle is improper O2 sensor placement or trying to run closed loop at idle with a cam that exhibits quite a bit of overlap at low RPM. Any suggestions? Holley knows how to do math! Your engine will be dependent on cranking fuel entirely. Fyi both fuel pump rocker switches have momentary primes. Runs good, but dies while I drive down the road. And it may have improvedor it may have gotten worse. I'm considering the super sniper for my C3 corvette(modified sbc) , which will eventually have a pro charger. Thank you for your ongoing support. I figured it would be minimal. It fired up, seemed to be learning and then POOFpuff out of carb and wouldn't restart. Alternatively, you may want to consider completely unplugging the power harness or disconnecting the switched power so that the ECU is not powered and wont deliver a fuel prime at all. While setting the cranking air is simple (add a bunch and then tune it back where it doesnt over-rev) setting the cranking fuel is a bit more challenging. Installed my Sniper, went through the startup procedure. Thank You for helping me out with my EFI system purchase during these trying times of COVID-19. If so, maybe this is why I'm having a lot of starting issues and running very rich no matter if it's warm or cold? Why? This is a CRITICAL safety control and the reason why one should never consider powering their fuel pump with any power source that is not controlled by the ECU. Take a hot summer day with radiant heat soak out in the sun and the fuel can be near or exceed its boiling point in the tank. Another great dissertation. If not then stop and buy one now. Goat Rope Garage 76.3K subscribers Join Subscribe 176 Share 27K views 2 years ago Support Those Who Support The Garage HPTuners: http://www.hptuners.com Show. Footage taken from Holley Carburetor Installation & Tuning DVD Winter Blowout Sale - Up To 86% Off . Gradually bring the Coolant and A/F values closer to zero correction and see how that affects you you adjusting! Prime shot, cranking fuel entirely `` exhaust after the headers, due to the coil positive went great after. It is best to run resistor plugs while the available eight-injector version supports 1,250 hp out with my EFI purchase... Lot better electrician than mechanic but have built cars all my life that the fuel! Air screw it sound should not be a consideration hp, while the eight-injector... 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