Misfires after swap
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This is a discussion on Misfires after swap within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; So i have checked many threads before asking this problem. I recently did a vf39 swap, pinks, intercooler, 255pump, gm ...

  1. #1
    Registered User Yellowsubi's Avatar
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    Misfires after swap

    So i have checked many threads before asking this problem. I recently did a vf39 swap, pinks, intercooler, 255pump, gm solenoid, and piping. After doing the swap, I initially had an exhaust leak which was giving me a misfire in #2,3 consistently, then when we fixed the leak, misfires came from 3,4 consistently. We then looked at the spark plugs and I had a stock one in cylinder 1 and irridiums in 2,3,4. My friend said being i have a 03wrx that i should not be runing irridiums. Changed those out to champion spark plugs (i know there not great) but nothing changed. So being it still had a rough idle, my friend and I isolated the trouble making cylinder (#3) by unpluging the coil pack. The car idled as if we hadnt unplugged it (it's idle was much worse when we unplugged any of the others). So we changed the pink injector on 3 and it began to idle somewhat normal when warm. Still rough when cold though.
    I thought we had fixed the problem as I have not recieved a code for a week, and one again it came on tonight. Always solid never blinking. The car was pretty cold when the code came on, misfire in cylinder 2,3,4. My question is do you think those irridiums messed something else up, because cylinder 1 was the only one with a normal spark plug, and its the only one not misfiring. The car has 25000miles on it and ive had it since 17000. I did the turbo swap about 1500 miles ago, and before the swap i never had any misfire codes.

    So all in all i have already swapped spark plugs, coil packs, injectors, and did a compression test, where cylinder 3 was the lowest at 148. Did a vacuum test and it was fluxuating up and down a lot around 15psi which is not good. Any ideas?? Because im lost, i thought since compression is good that it cant be the valves, but i think valves explain the loss and fluxuating vacuum reading.

    On side note I have an xpt tune which i logged today and hope to hear back from them soon, but this misfire thing is getting annoying. Any ideas? valves or something else??
    Last edited by Yellowsubi; 06-20-2009 at 12:29 PM.

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  3. #2
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    A simple exhaust leak will not cause a misfire (unless it's a pre-turbo leak that will cause you to run extremely rich).

    Misfires can be causes by about a billion things. They are the single most annoying issue to track down.

  4. #3
    Registered User Yellowsubi's Avatar
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    yeah it was a pre turbo leak, my egt bung was not filled, the bolt popped loose.

    but what im worried about is what causes a fluxuation in vacuum like that??

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