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Car runing rough after the exaust went on.

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  • #1

    Car runing rough after the exaust went on.

    I installed my headers and new opti this week, i started the car up last night open header and it ran perfect. This morning i took it in to get it hooked up to my exaust, the guy welds it up ( no cats ) lowers the car and when he starts it its runing like garbage. goes to back it off the lift and it stalls out when he put it into reverse. it idles at like 500 but its realy rough and you can barely hear the car ( its quieter than before ). I just dont get how it would do that when it was running fine before i took it in.

    Possible things :
    EGR tubes are not hooked up
    Opti ???
    Plugs ( i have autolite #106 gaped at .050 )
    -Nick-
    95 A4 Z28
    Tags: None
  • #2
    Is it missing? If it ran fine before, I suggest looking at the basics first....plugs, wires, etc... My car did that before....low idle then just choked out on me. It wound up being that I didn't have the bottom portion of my rubber intake elbow over my TB completely. Did you install your opti correctly?
    black 95 t/a, a4, beefed up tranny w/ higher stall converter, transgo shift kit, trans temp gauge, trans cooler, richmond 3.73's, loudmouth, hypertech programmer, 160 thermo, descreened maf, TB bypass and airfoil, trick flow intake elbow, underdrive pulleys, moroso cai, edelbrock panhard rod, bmr stb, slp sfc's, fiberglass firehawk hood, hawk pads, taylor wires, ngk plugs, royal purple fluids,...and hopefully more to come

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    • #3
      Did the guy at the shop pull the cables off the battery before he started welding? If not, it is very possible to damage the sensitive electronics, including the PCM.

      It is also possible, and even likely that you have wires burning on the headers, poor extensions (if you needed them) or contaminated O2 sensors.
      Fred

      381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

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      • #4
        ok, either I missed it or you didn't mention it, but since you said you took out the cats, did you get the O2 Sims?!?!?
        Richard Harvey Jr.
        '94 T/A LT1 (stock) - SOLD

        Comment

        • #5
          Originally posted by TruckMuddr
          ok, either I missed it or you didn't mention it, but since you said you took out the cats, did you get the O2 Sims?!?!?
          He has a 95. He doesn't have after-cat O2 sensors, so "sims" are not applicable.
          Fred

          381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

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          • #6
            hmmm


            ***Opens mouth and inserts foot***
            Richard Harvey Jr.
            '94 T/A LT1 (stock) - SOLD

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            • #7
              its not missing, just at idle it seems like the car wants to stall out. when im driving like on the highway or something of the sort it seems to drive fine.
              -Nick-
              95 A4 Z28

              Comment

              • #8
                Originally posted by Injuneer
                Did the guy at the shop pull the cables off the battery before he started welding? If not, it is very possible to damage the sensitive electronics, including the PCM.

                It is also possible, and even likely that you have wires burning on the headers, poor extensions (if you needed them) or contaminated O2 sensors.
                Take note of what Fred posted....... often times welders forget to disconnect the battery. Torch welding isn't usually an issure, but electronic...... you bet. That can cause a myriad of problems. You may want to clear the PCM by pulling the fuse and see if that does it. Your IAC may also be stuck. Tough to diagnose without hands on.......

                I've said it many times and I'll mention it again. A scan tool is one of the first additions that should be made to your box of tools. To be able to read what the sensors are doing in real time takes so much of the guesswork out of the equation.

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                • #9
                  Try the "IAC reset" procedure on Shoebox's Tech Pages.

                  Fred
                  Fred

                  381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

                  Comment

                  • #10
                    come to think of it guys, he may not have disconnected it. i was right there while he was working on it and i dont recall him disconnecting it before the car went up. ill give it a shot in the morning and see how it goes.

                    and joe, i agree with you 100%. and probabally will be purchasing one very soon.
                    -Nick-
                    95 A4 Z28

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