Red Nightmare Posted January 4, 2011 Report Share Posted January 4, 2011 1994 3.4 DOHC GTP. I thought the problem was solved but didn't know how. Today I went out to start it and the problem seems to be back. It starts easily, but once it settles from the 2000 RPM after a few seconds, during warm-up it runs as if it is missing a cylinder. Once it is warmed up a bit, like after 5 minutes it runs smooth. What I have checked/fixed - PCV cleaned. EGR cleaned. IAC cleaned. No check engine light (it does work though) Spark plugs not fouled they look good, recently replaced. I reconditioned the plug wire connectors. Wires ohm test good. DIS coils all look good, no corrosion or rust on terminals. All fluids good. Fuel pressure good at priming and engine running. Fuel pressure regulator recently replaced (it had failed completely) Air filter not clogged. Voltage good, increases slightly when engine running (as normal.) Not smoking excessively, just the normal steam when it is cold outside. Now one thing I read somewhere was about a possible coolant temp sensor being bad. I found this sensor and it looks impossible to get to without taking off the UIM. If I knew what wires from the PCM lead to it I could probably check it easily but I don't want to have to remove the UIM if I don't really have to. If this sensor were to fail, would it throw the CEL or would the engine just think it was hot or cold ALL the time? Where should I look next or should I even worry about this? If it is not a catastrophe, I could live with it but would like it to not run like crap on startup. Ideas? Thanks. Quote Link to comment Share on other sites More sharing options...
Red Nightmare Posted January 14, 2011 Author Report Share Posted January 14, 2011 So with the coolant temp sensor, I know where that is but of course looks in accessible without taking off UIM. Is there a way I could test it thru the wiring from the PCM? I am not sure which wires lead to it. BTW the check engine light has not come on or anything. Does anyone know where I could get a PCM layout? 1994 grand prix gtp 3.4 Quote Link to comment Share on other sites More sharing options...
Red Nightmare Posted November 15, 2011 Author Report Share Posted November 15, 2011 I got around to digging more into this, got tired of living with it. Turns out the intake gaskets were bad. I did the upper and lower. Thing seems to run fine now. Quote Link to comment Share on other sites More sharing options...
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