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Thread: L67 coughs badly

  1. #1
    Tuner
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    L67 coughs badly

    I'm scanning a local's 2001 SSEi Bonneville and its got an ugly cough under light or full throttle.

    Many variables take a nasty drop on the chart such as timing, injector duty, o2's, and sometimes the rpms.

    The owner already replaced the front o2, coil packs, fuel regulator, and fuel filter.

    Please take a look at the attached scan and let me know if this makes any sense.

    Here is a sneak peak:

    2009 G8 GT - White Hot

    226/234 601/601 112+4, Yank SS 3600, SLP Longtubes, Magnaflow exhaust, Rotofab, 3.91 Rear

  2. #2
    Advanced Tuner
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    Mine does this once in a while too..... don't know.
    Electrical gremlins, short = poor grounds?
    The Regal has been laid to rest..... rust
    Now have an 06 Lucerne with the 3.8 and wishing HPT would cover that car
    Loved my 2001 Buick Regal GS.
    With more than 334,000K, 3.4 & 3.6 pulley, Change stats and pulleys with the seasons, Upgraded grounds & power wire, Volt booster, Caspers timing commander(AKA happy knob), Spectra intake-fender wall, PLog, 3" DP & 2.5 exhaust, HPTunner 12" Impala duel piston front brakes, New trans,GMPP suspension... yada, yada...

  3. #3
    Advanced Tuner ajamesbond007's Avatar
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    I wonder why you get a big shot of KR right after the coughs, mainly 2nd and 3rd...
    Andrew

    2006 Duramax ECSB - Banks Monster Dual Exhaust, Tie Rod Sleeves, Kennedy Twin Deluxe Lift Pumps, Edge Insight CTS with Pryo, EGR Blocker Plate, PVC Reroute, Suncoast Stage 5 trans with 1056 triple disk converter, Cognito Steering Braces, PPE Race Valve, LML driver side exhaust manifold, AFE Boost Tube, Stock Drop-in BatMoWheel, ProFab Performance 3" Downpipe, Other mods along the way, TUNED by ME... Way too much fun

  4. #4
    Advanced Tuner
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    Look how his KR is in correlation to the shift into 2nd.
    The Regal has been laid to rest..... rust
    Now have an 06 Lucerne with the 3.8 and wishing HPT would cover that car
    Loved my 2001 Buick Regal GS.
    With more than 334,000K, 3.4 & 3.6 pulley, Change stats and pulleys with the seasons, Upgraded grounds & power wire, Volt booster, Caspers timing commander(AKA happy knob), Spectra intake-fender wall, PLog, 3" DP & 2.5 exhaust, HPTunner 12" Impala duel piston front brakes, New trans,GMPP suspension... yada, yada...

  5. #5
    Senior Tuner
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    Post the tune file.

  6. #6
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    Stock tune.

    I'm really at a loss on this one and I used to be heavy into tuning L67's.

    2009 G8 GT - White Hot

    226/234 601/601 112+4, Yank SS 3600, SLP Longtubes, Magnaflow exhaust, Rotofab, 3.91 Rear

  7. #7
    Senior Tuner
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    I would have a closer look at dampner/reluctor, crank sensor, cam sensor, and ignition module. The injectors are actually shutting off when this happens. Cam and crank sensor feed into ignition module then to the pcm.

    And the ltft's are maxed out through most of log if your making changes.

  8. #8
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    The LTFTs being maxed made me think gasket leak, but then I remembered an old '94 3800 I had with a bad crank sensor doing this under uphill load.

    I would be surprised if the crank sensor went on a 2001 with 50k-some miles, but you never know.

    2009 G8 GT - White Hot

    226/234 601/601 112+4, Yank SS 3600, SLP Longtubes, Magnaflow exhaust, Rotofab, 3.91 Rear