Question about 1987 Chevrolet Camaro

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Runs good with ecm un-plugged in, but when plugged in runs rough

Ive replaced, plugs, wires, got a new comp, with a new prom, fuel pump, all those were bad before, but now i cant seem to get it timed right when the ecm is plugged in it runs rough and the timing notch on my camshaft is jumpin back and forth, i thought it was a vacuum so i un-plugged my iac while it was running and nothing changed so im led to believe its that. Any ideas? I would just run it without the ecm, but im in Arizona and you have to pass emissions, and im sure ide go threw these injectors pretty quick with how much fuel ide burn. Thank you. Troy

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  • Troy Kirby
    Troy Kirby Apr 23, 2009

    left hand inner skirt? do you mean under the hood by the firewall passangers side?

  • Troy Kirby
    Troy Kirby Apr 24, 2009

    yeah thats what i mean by it being plugged in, if i un-plug it then it by-passes the computer completely im pretty sure, and my check engine light is on, thus making it fail emissions and Arizona is crazy about that.

  • Troy Kirby
    Troy Kirby Apr 24, 2009

    yeah tried it and it didnt work. im pretty sure its a sensor cause it runs fine with it un-plugged but when i plug it in it starts running rough again, so its something going threw the ecm. thanks for your help though


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Static timing should be 10 deg btdc you can check that timing when you disconect the tan/black trace wire there should be a weatherproof connector for this wire near the Left hand inner skirt this wire is called the set timing connector and when disconnected stops the ecm from adjusting the timing.

Posted on Apr 23, 2009

  • Vikinge Apr 24, 2009

    My appologies it is under the hood on the right hand side you will see the weatherproof housing normally taped to the ecm harness near the a/c housing

  • Vikinge Apr 24, 2009

    You will have to set the timing without the engine running 10 deg BTDC should work properly after that and you can plug the wiring back in


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