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Thread: First fire up stumbles. COS3 80lb 5.3L ls6 cam

  1. #11
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by jay_rich View Post
    Just thought of something. i havent finished putting my trans in. So I havnt hooked up any linkage OR the NEUTRAL SAFETY SWITCH WIRE. Does anyone know if this prevents the pump from suppling fuel after the car has been started. Im almost wondering if the car is firing off the fuel thats in the rail then dying out. Its hard to check the pressure since I have an adjustable regulator that bleeds off as soon as the car is fired. it is a simple fix when I get home. ill just ground the wire for now and see.

    Jay
    No, it does not stop the fuel pump from running.

    Is this what you're seeing, the fuel pump is not running...? When you key-on do you hear the fuel pump prime for 2 seconds...?

    To measure FPR/rail pressure, remove the fuel pump relay and jumper the socket (using a fused jumper wire) so the pump runs; then remove the reference hose and measure rail pressure.

  2. #12
    Joe (Moderator) joecar's Avatar
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    Did you try this:

    Quote Originally Posted by 240sxpooter View Post
    ...
    Also can you keep the car running by giving it gas?

  3. #13
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    Yes the fuel pump primes on initial key ON and when the PCM is finished tuning.

    When i give the car throttle is dies pretty well instantly. I guess next will be hook the neutral switch up then possible jumper the fuel pump.

    I was having a hell of a time trying to set the rail pressure since the car was just priming for 2 seconds (filling 8an feed and 6an return).

    I will report back later tonight.

    Jay

  4. #14
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    is the rail holding pressure after it primes?

  5. #15
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    It is not but its expected with the adjustable regulator. They bleed off the fuel. Its the "summit" version or of the aeromotive 13109.

    Jay

  6. #16
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    Well didnt do a thing but toss a new tune in it and it fired and ran beautiful. Not sure what i missed on my tune.

    Jay

  7. #17
    Joe (Moderator) joecar's Avatar
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    Can you compare the old and new tunes (using the compare feature in the tunetool)...

  8. #18
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    I plan on doing that when I have time this weekend. Its still bothering me what I missed. I basically started with a stock 2002 5.3L file. Did the COS3 and verified everything matched my friends tune for that. VATS/Column Lock was disabled, etc. Unless it was the injector tuning. I did update the voltage offsets to match what i found online.

    Left all the parameters stock but updated the Flow rate (10.079) (43.5psi base 1:1 regulator) then the Voltage offset as following.

    6V=2.811MS
    8V=1.777MS
    10V=1.288MS
    12V=1.017MS
    13V=0.903MS
    14V=0.801MS
    15V=0.721MS

  9. #19
    Lifetime Member Boost's Avatar
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