LT1-LT4 Modifications 1993-97 Gen II Small Block V8

problems...

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Old May 11, 2009 | 09:44 PM
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scj
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Default problems...

ok, so i previously had problems with excessively high idle, 1500 rpms, along with a misfire.

the high idle ended up being the IAC valve, and the EGR valve/solenoid. which i had codes for both. so the idle is fixed, now i'm still struggling with the misfire.

i'm throwing "p0300-random multiple misfire."
the only time i can feel or hear the misfire is once the engine is warmed up, and only at idle, not at WOT.

now,... i was told that i could be the coil, opti, ICM, plugs, wires.

well the plugs are new nkg tr55's, and the wires are new factory replacement wires. which would rule those two out, because i'm not getting any arcing or anything like that.

i was told that if the ICM or coil was in fact bad, the car would have problems starting or running at all, which is not my problem, so i wasn't thinking this was my problem either.

leaving only the opti as the culprit, but it's sparking fine when i unplug the distributor boots from the opti, which is really throwing me for a loop.

then, i was told that it was in fact the o2 sensors because of the open/closed loop problem. seeing that my MAF sensor is new.

so i figured if i unplug the first two o2 sensors and if it still ran bad then that was my problem.
i did so, and the car seemed to run the same.

the EGR,IAC,MAF,TPS, plugs, wires, are all new.

is it the coil, opti, ICM, or o2's that are causing my problem?

HELP please? i'm tired of spending fixing money on this car, i want go fast parts,and mods.
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Old May 11, 2009 | 10:43 PM
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When Ive had coils go bad the car wouldnt run. When the ICM goes bad generaly it will stop working after it is heated up by the engine, then the engine will die. Most cases it will start up again after it cools down.

Pull two or three plugs and see what they look like. If they are all dark and smell like gas then theres one problem. It could be that the o2s are bad and causing it to run in open loop rich as hell. Your plugs may be fouled. If they are a not gas fouled then you might start looking into the distributor. Just because you can see a spark does not mean that the spark is hot enough to ignite the combustion chamber. Also check the porcilin of the plugs where the boot slips over and check for signs of arcing. You can also check the opti harness and make sure it is plugged in good and tight or if its damaged.
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