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  • I need some help

    I've got a 94 firebird, formally V6, that I put a 97 5.7 & A4 in. I swapped the front K member, tranny, radiator, ecm, etc, and put a loudmouth exhaust w/sims on it. Now for the problem.

    Car sits and idles fine, runs strong when you step down on it, but at light throttle, example( driving through town, going up a small grade, cruising on the interstate), it misses badly causing a surge similar to cruise control. It will miss, then surge up a couple of miles per hour, then back to miss again, repeatedly.

    I've changed the pcv, all associated hoses and gromets myself. Took it to the local pontiac dealership, they scanned it and said it is missing on two cylinders, but not the same cylinders. They said "the miss was all over the place". They changed the maf and crank position sensor, and those had no effect on the operation. Then they said they didn't know what was causing this, but a good place to start would be by replacing the opti, but they didn't know if that would solve the problem, it could be something else. Since I had already spent a bunch with them, and received no operating improvement, I told them I was stopping right there, and taking it home with me. I'm not about to put another $8 - 900.00 in it, and possibly still have the problem.

    Any help identifying the problem area would be greatly appreciated.

    Thx,

    Cliff

  • #2
    I'd replace the plugs and wires. If not that then its problably the opti.


    LT4KM, 160' TS, MAF ends, TB-BP, GMPP 1.6 R/R, SLP CAI, LCA, Adj. tierod, BMR tower brace, 17x9"F/R, 275/40R17 GY F1 tires. WS6 Muffler, LS1 DS. 21mm rear sway bar. Soon to be LT4 heads, intake, & HOT cam

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    • #3
      It could be a few things, opti is one of them for sure. Ever think of checking the fuel pressure or changing out the fuel filter?

      Does your car have a vibration even when it seems to be running fine?

      I am by far from a expert but if the GM techs are saying the miss is acting up all over, it is probably something affecting everything. Maybe even the O2 sensor could be going south.
      94 Formula Firebird, 355, heads port and polished, cc503 cam, 30# injectors, PCMforless Tune, B&M 2400 stall, K&N CAI, BBK Sorty Headers, Magnaflow Highflow Cat, Borla Catback exhaust with electronic cutout.

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      • #4
        While my 93 firebird has a V6 in it, I had the same symtoms and problems you were having...I put up with it for as long as I could until the one day that I just couldnt stand it any longer. The dealership looked over it and found that it had a bad lower intake gasket. They changed it....havent had a problem with it in the last year. Actually picked up 3mpg as well. Runs better than the day I bought it.
        LarryMow-93 V6 Firebird-No engine mods-Z06 Wheels, '98 Taillights,'98 Center Console-SLP fan switch-BMR STB, F/R Swaybars, PHB,LCA,Torque Arm, SFC, Bilsteins, Eibachs....www.cardomain.com/ride/2489691/1

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        • #5
          Thanks for the help guys. Today I changed the pcm, that didn't help any. The strange part is that it throws no codes. It has new plugs and wires, with less than 1K on both. I put them in when installing the motor. The engine had approx. 100K when installed, and ran good for about a week before this began.

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