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Thread: Couple issues, can someone look at my log?

  1. #1
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    Default Couple issues, can someone look at my log?

    My car has decided to randomly start dying every so often. It only does it from idle and often during braking or turning, especially on inclines.

    It doesn't seem to stutter out so much as just die like I reached up and turned the key.

    Also during cruise when I let off the rpms hang then fall then rise, during this the timing is going from normal to 2* then back to normal. In my timing tables I'm not seeing any strange blocks that would explain the drop.

    Any ideas?
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    71 Chevelle, LS1/4l60e, EPS 230/238 113+2, hand ported 799s, ported Fast 90/90, Doug's headers, 3.42 12 bolt

  2. #2
    Joe (Moderator) joecar's Avatar
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    Any DTC's...?

    Can use your V2 to pull DTC's... (if you setup the DTC's in the S&T black box configuration "Tune Settings" tab, V2 will say in English what the DTC means)

  3. #3
    Joe (Moderator) joecar's Avatar
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    I can't see reason... check/clean power and ground connections for voltage drop (there should be less than 0.2V drop)...

    Do you have all the grounds listed in the PCM connector pinouts...?

    Do you have the head/block ground connections...?

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    Joe (Moderator) joecar's Avatar
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    Unrelated comments:

    PCM is seeing the TCC slipping... have to do something about this, increase the min TCC pressure/PWM to 80+%, see table D2903.

    I see IAT responding to ECT increase (IAT seems to lag about 30 seconds behind ECT)... you might have to relocate intake duct to get more direct cold air.
    Last edited by joecar; July 27th, 2010 at 04:13 PM.

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    The grounds on the head and to the battery are good. I'm going to run an extra ground to the fuse block since its just grounding through the fuse block mounting screw now. I'm going to try to borrow a jack to check starter wires and look below for any obvious issues.

    The car has a 3600 stall, what will adjusting the table you mentioned do? Just set so the pcm only sees slip when it crosses a higher threshold?

    The intake ducting is the best I can do right now until I can find or make a tube with a dimple to cross the radiator hose so the intake can draw air from the driver side behind the headlight. Right now there's no choice but this:



    What about the timing issue on deceleration? Any ideas what could be causing it to pull all but 2* and then toss it all back in? I might need to call my tuner about that one. Problem is he is 4 hours away otherwise I would just take it back to him.
    71 Chevelle, LS1/4l60e, EPS 230/238 113+2, hand ported 799s, ported Fast 90/90, Doug's headers, 3.42 12 bolt

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    The IAT is in the filter rubber right where it meets the MAF. If I turn on the cooling fan on that side of the engine the temps drop by 20* which helps some. I still want to make a better cold air system somehow.

    No DTCs now, last week it tossed a code once for the TCC brake switch (which might be on the same circuit as other sensors? maf maybe?) but after I cleared it, it never came back so far.

    Sometimes the car does struggle a moment to find clean idle at stops, with rpms dipping to 500rpm and lower but it catches quickly.

    Should I crack the throttle blade and reset the tps/ idle relearn or raise commanded idle? It is set to 850rpm and timing jumps around a lot there.

    Also is the PID for oil pressure invalid for my application or something? I noticed it is hung on one low voltage value and never fluctuated. I've never scanned its output before.
    71 Chevelle, LS1/4l60e, EPS 230/238 113+2, hand ported 799s, ported Fast 90/90, Doug's headers, 3.42 12 bolt

  7. #7
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by thunderstruck507 View Post
    ...
    The car has a 3600 stall, what will adjusting the table you mentioned do? Just set so the pcm only sees slip when it crosses a higher threshold?
    ...
    Does your stall have a TCC lockup clutch...? If it does, then the lockup is slipping. (It looks like it has a lockup clutch.)

    [ TCC = torque converter clutch = lockup clutch ]

    Add TCCMODE and TCCDC when you next log... when TCCMODE says Locked, then TCCSLIP should go to pretty much zero.

    [ keep the pid channel count no larger than 24 for fastest sample rate, I want to see any transitions ]

    When you open the throttle the TCC apply/release tables will unlock the TCC allowing your stall to do it's job;

    when you go back to cruising, the TCC apply/release tables will lock the TCC allowing better fuel mileage and keeping fluid temp down.

    If you look at TCCDC when TCCMODE is Locked, you will see that it is below 80%, allowing the TCC to slip during cruising.

    Slipping means the TCC is dragging/slipping, which wears out the clutch friction surface and raises the fluid temp.
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    Last edited by joecar; July 28th, 2010 at 03:14 AM.

  8. #8
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by thunderstruck507 View Post
    ...

    What about the timing issue on deceleration? Any ideas what could be causing it to pull all but 2* and then toss it all back in? I might need to call my tuner about that one. Problem is he is 4 hours away otherwise I would just take it back to him.
    To see why timing is being pulled, log the pid whose names look like EST_xxx_DMA... these may give a hint to where timing is going.

    [ EST = electronic spark timing ]
    [ DMA = direct memory access... (not a GM provided pid, but EFILive knows where to look for this in the PCM's memory ]

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    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by thunderstruck507 View Post
    ...

    The intake ducting is the best I can do right now until I can find or make a tube with a dimple to cross the radiator hose so the intake can draw air from the driver side behind the headlight. Right now there's no choice but this:
    ...
    Ah, I see.

    Very nice and clean engine bay, big and roomy... nice car

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    I will check on that then, doesn't sound good...doesnt seem to slip at cruise though.

    I will also try to log the timing.

    What about the oil pressure? bad sensor maybe?
    71 Chevelle, LS1/4l60e, EPS 230/238 113+2, hand ported 799s, ported Fast 90/90, Doug's headers, 3.42 12 bolt

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