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Discuss new problems after cat was replaced,PLEASE HELP!!! in the alt.autos.gm forum at Car Dealer Forums; here's what happeened in chain of events,maybe someone can be of help?3.4,, 94 grand prix ...
  1. #1
    robert -wanda fox
    Guest

    Default new problems after cat was replaced,PLEASE HELP!!!

    here's what happeened in chain of events,maybe someone can be of help?3.4,,
    94 grand prix engine, after taking cam covers off and replacing timing belt
    and properly timing the cams,along the way replacing back o2 sensor,and
    dropping new set of plugs in,replacing a melted pcv line,started car up,ran
    great all cylinders up and power galore,but of course cat converter was
    making awful noise,all broken up inside,although it was making noise before
    belt gave out it was somewhat louder now after many starts working on car
    and several times timing out till put in correctly,at the gas station while
    fueling up,i had hood up and hand throttled it a little checking up on it
    and heard a loud hiss for a few seconds(like a air release)then the engine
    began to idle roughly,it was now missing and the cat converter really got
    loud and noisy,i took it the next day to have tehe cat replaced and somewhat
    did a diagnosis on the car,it appears no vaccum leaks (that i can detect
    anyway)it appears three cylinders are missing(and each cylinder is on a
    different coil pac,there isn't two on the same pac like a bad pac,)this can
    be deceiving because the car is running good enough as if only one cylinder
    is dead,but upon driving the car seems to smooth out and a lot of power
    driving,just at idle is the miss(s) noticable,you can hear and feel the
    popping and missing out the tail pipe too,another thing i noticed too,,upon
    throttling fast and consistant under the hood,the rpm's will want to keep
    cutting back at a certain point. any ideas what the hiss sound was upon
    throttling then the rough idle started?????,,thanks



  2. #2
    asadi
    Guest

    Default Re: new problems after cat was replaced,PLEASE HELP!!!

    ..?',()!";":..CAPS

    Insert as necessary.

    lol....john

    "robert -wanda fox" <res0ta8b@verizon.net> wrote in message
    news:sU_Fg.3647$hP6.1952@trnddc04...
    > here's what happeened in chain of events,maybe someone can be of
    > help?3.4,,
    > 94 grand prix engine, after taking cam covers off and replacing timing
    > belt
    > and properly timing the cams,along the way replacing back o2 sensor,and
    > dropping new set of plugs in,replacing a melted pcv line,started car
    > up,ran
    > great all cylinders up and power galore,but of course cat converter was
    > making awful noise,all broken up inside,although it was making noise
    > before
    > belt gave out it was somewhat louder now after many starts working on car
    > and several times timing out till put in correctly,at the gas station
    > while
    > fueling up,i had hood up and hand throttled it a little checking up on it
    > and heard a loud hiss for a few seconds(like a air release)then the engine
    > began to idle roughly,it was now missing and the cat converter really got
    > loud and noisy,i took it the next day to have tehe cat replaced and
    > somewhat
    > did a diagnosis on the car,it appears no vaccum leaks (that i can detect
    > anyway)it appears three cylinders are missing(and each cylinder is on a
    > different coil pac,there isn't two on the same pac like a bad pac,)this
    > can
    > be deceiving because the car is running good enough as if only one
    > cylinder
    > is dead,but upon driving the car seems to smooth out and a lot of power
    > driving,just at idle is the miss(s) noticable,you can hear and feel the
    > popping and missing out the tail pipe too,another thing i noticed
    > too,,upon
    > throttling fast and consistant under the hood,the rpm's will want to keep
    > cutting back at a certain point. any ideas what the hiss sound was upon
    > throttling then the rough idle started?????,,thanks
    >
    >




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