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Thread: Idle issues and lots of knock

  1. #1
    Electronic Ignition!
    Join Date
    Jul 2014
    Location
    Eagle, Idaho
    Age
    56
    Posts
    18

    Idle issues and lots of knock

    After a year+ of repairing the more obvious issues on apreviously ignored vehicle, I'm trying to address my funky idle and high knock count.

    My idle cansometimes (rarely) be smooth as silk but most of the time it produces a steadyvibration at idle and the idle fluctuates or pulses. This is also noticeableduring deceleration although a bit more rhythmic. For example coming off thefreeway and coasting to the light.

    In PARK (750~RPM)worse than in Drive (560~RPM). Decel with foot off accelerator produces a moresteady pulse. Pulse…Pulse…steady……..Pulse……steady……Pulse…Pulse…P ulse.

    Inreading the description of "INT vs Airflow" in TunerPro, maybe it is worth mentioning thatthe snorkel on the air filter has been cut off because it interfered withaftermarket AC lines and compressor. So - big hole in the side of the air filterif it matters.
    Smogpump is disconnected and check valves on air injectors on manifold are blocked.
    Recentlyremoved CAT, because it was disintegrating and falling apart along with the oldmuffler. Exhaust now consists of a new 3" pipe from the "Y" to anew 45 dollar muffler.
    Timingadvanced about 5* via distributor.
    65pphinjectors - new last year. Same symptoms with 2 other sets of injectors.
    Fuelpressure = 13psi
    RebuiltTBI. Including re-bushed throttle shaft.
    Ithink the only thing I haven’t replaced is the MAP sensor.

    Attached log has acouple minutes of idle in PARK, a couple minutes of idle in DRIVE then streetand freeway driving then idle in Park and Drive again at the end. Stock ASDUbin with SA and BPW hack applied.


    Any assistance wouldbe appreciated.
    Attached Files Attached Files
    '87 Chevy G20 Van
    350 from '90, 9C1 Caprice
    7747

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