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Thread: Sniper runs perfect, then no start or communication until it cools off.

  1. #1

    Default Sniper runs perfect, then no start or communication until it cools off.

    Have a Sniper 550-510K we just installed for a customer, started & runs flawless. I brought it back to the shop and 30 minutes later went to move it and it just cranks. No fuel pump, monitor powers up, but under gauges says "no data" on every selection, so it's obviously a communication issue. Pushed it inside, came back the next day and fired up and ran perfect. Drove it around, let it sit, did a bunch of restarts with no issues. Figured it was a fluke deal, drove it again and all good. Customer picks it up today, makes it home, lets it sit maybe 20 minutes and he gets the same deal. No fuel pump, just cranks, won't start. He's 30 minutes away so by the time I get there, I reached in and it fired up perfect. He's very pissed off since he just replaced a different EFI with the system, because he had issues with the other one too. Not using the timing control, fan control, etc., just the very basics. I verified 12V switched/constant/ground when it was here and had the issue. I believe it's simply a heat issue with the ECU, but trying to come up with any other ideas and especially any remedy for it. I called tech and they asked me to do a datalog, but it can't datalog if there is no communication with any sensors and won't start. Any help would be appreciated, on hold now for the past 30 min with tech again. Thanks, Justin.

  2. #2


    Since no one has chimed in for 5 days, I'll give you my thoughts. If this is indeed a hot CPU issue (not saying it is, and it's not something I've heard about happening, but was always in the back of my mind), it sounds like it runs cool enough, but heats up when the heat soak after key off occurs? I would stick a thermometer or non-contact IR gun to the Holley, so you can see if temps are insanely high. Hot carbs can boil fuel. To combat this phenolic spacers, air-gap manifolds, heat shields can be implemented, all of these could be solutions for a hot Sniper IMO if Heat is the actual culprit.

    No fuel pump, monitor powers up, but under gauges says "no data"...
    This tells me the CPU is on, but not processing data?
    Last edited by Zmann; 08-18-2017 at 03:42 PM.

  3. #3


    I just saw this. I like the idea of the phenolic spacer for this reason, and I've also read it may help with idle surging issues.

  4. #4


    I just installed my Sniper and have been having issues too. But just came across this. Maybe this will help:
    "Idling: Once the Learning has finished self-tuning the Base Fuel Table, enter the Learn Parameters and decrease the Learned Compensation Limits % down to around 2% in the idle area. The reason why is, the idle can go through repeated 'cycles of Closed Loop compensation' (+/−). When you're idling for a long period of time, the electric fans are regulating the cooling system temperature between 200° & 190°. This temperature variance can cause the Closed Loop to add & subtract a significant amount of fuel (as it should), especially if the fans are powerful & blowing hot air at the throttle body. However, you don't want the Learn Table to constantly modify the Base Fuel Table with these temporary corrections. If you shut off the engine during the lean end of the "cycle", the Learn Table has self-tuned the idle area as such, and may run momentarily lean on the next startup. Closed Loop is not saved, so it's allowed to constantly fine-tune the AFR. Learning is saved (and its values modify the Base Fuel Table), so it should be limited once the engine is tuned."

  5. #5


    Unhook the handheld and see if it will start. We had one of the really early Snipers and had multiple problems with it. One being the the handheld. It would show no data after it ran for a while and wouldn't start. Talked to support and they said it was the handheld. I had another one so I used it. However, I never tried it without the handheld to see if it would start.

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