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Thread: Weird sudden stall...it's immediate.

  1. #1
    Fuel Injected! woody80z28's Avatar
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    Weird sudden stall...it's immediate.

    Working on my tune for my Beretta (7730 $A1) and ran into a new problem. I've been using this same car, ECM, sensors, etc and basic tune for many years. Changed heads & cam and injectors and the main thing that's different is the BPC vs EGR to account for the injectors.

    Several times (probably almost a dozen) in the last couple days it has suddenly stalled. And it's immediate like I turned the key off. Fires back up no problem though. And it has only been while idling, or when coming back down to idle after disengaging the clutch. I noticed in the logs it goes from normal readings to dead readings in one sample. Capture attached.

    Not sure what I got going on here. Any ideas? Attached a log and my ADX too. Thanks
    Attached Images Attached Images
    Attached Files Attached Files
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

  2. #2
    Fuel Injected! woody80z28's Avatar
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    So, the car sat in the garage for a few days while it was snowing outside and now it doesn't run. Gives me a Code 51 PROM error and will barely start and miss horribly. I think it's running off the limp tune.

    So I put in another PROM I had and it did the same thing. So I even burned a tune 1 step back that I know ran. Same thing. Think the ECM is shot?
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

  3. #3
    Fuel Injected! S.O.B.B.'s Avatar
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    Don't know if this will help but I had the same code on my setup on initial trying to start engine.it was the chip not making contact.at key on the check engine light would come on then off then flash quickly. Once the chip made proper contact on all the pins it worked.I also had the same problem after soldering in a chip socket.I checked continuity to each pin with dvm and found one not making contact. U might try wiggling the chip and see if it starts.hth
    Jeeper
    87 sjimmy 4.5L /nv1500/ 8.8 3.55 rear/disc brakes.

  4. #4
    Fuel Injected! woody80z28's Avatar
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    Thanks for the reply. I'll check out the pins on the ECM itself and see how it looks. I have had stuff in & out of there a hundred times. I did try two Memcals, two different 27SF512 chips, two tunes and also the ribbon for emulating.
    So the ECM seems like the only common denominator left.
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

  5. #5
    Fuel Injected! woody80z28's Avatar
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    Pins on the old ECM look fine, but a new ECM fixed the Code 51 and it's back to running like it was.

    I haven't run into the sudden stall again, but only took a quick spin once I got stuff changed around.

    One thing that is super obvious that I forgot to ask about is shuddering when decelerating. I have to disengage the clutch when slowing down for a stop sign, etc. because it lurches. But it starts lurching at like 2000rpm and it never did that before this cam swap and new injectors. I'll search it too.
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

  6. #6
    Fuel Injected! woody80z28's Avatar
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    New, similar problem but different. The new ECM fixed the sudden stall. But now I have a stall at the same time (returning to idle from a higher rpm when disengaging the clutch) that is a little slower. I can catch it with a quick throttle stab usually. Looking at the log I see the base pulse width shoots to the moon right before it stalls.

    I've posted a log, as well as my adx and bin. The adx has BLM/INT converted to 100 stoich and my wideband in it.

    Something strange I've noticed that might be related...the idle seems quite close to 100 BLM/INT in closed loop sometimes, and others it drops down in the 80s. What could cause that, a temp scalar or something?

    First stall is at 2:30, another at 2:54, 4:09, 11:26, 14:00, 17:00, 17:34 (different from the rest - wierd iac), 20:44, 25:16, 26:59.

    Any help is appreciated.
    Attached Files Attached Files
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1)
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D)

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