1995 chev van 350 tbi ping or knocking

Discussion in 'General Chevy & GM Tech Questions' started by easy, Jul 29, 2013.

  1. easy

    easy New Member

    start van runs ok. take off up to 35 mph ok. give gas at pedal to go faster and ping and or knock is noted and lost of power. slow down below 35 and runs good. no check engine light is on and light is ok. pulled intake and put vacuum on egr valve valve holds good vacuum. already replaced timing chain and gear before so this was not the problem. did a tune up when timing chain was replaced. I am thinking the cat is almost stopped up and to much back pressure on accl. is causing the problem. but I don't know. What do you think.
  2. mfleetwood

    mfleetwood Epic Member 5+ Years ROTM Winner 5000 Posts

    Welcome to the Club!!!

    I moved your thread to the correct section of our Forum. This should help in getting your more responses/opinions. Unfortunately, I do not know what the problem(s) could be...
  3. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    In the old days a buildup of "carbon gunk" in the combustion chamber could cause knock
    detonation of preignition
    Was it running poorly for some reason -before this started
    Poorly enough so you weren't getting a good burn-?
    Then you fixed something? Maybe intake leak or even exhaust manifold leak plugged TBI
    bad ignition-
    Maybe folks here swear by seafoam to clean combustion chambers
    GM actually makes some GM combustion chamber cleaner

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