Weird Missfire.. Comes and Goes

[Shocker]

Well these past few times I have had my car out ( I live in Ohio, so it only goes out when its not snowing and above 35-40 degrees..) I have noticed a slight missfire under WOT from 4-7 k. It was rather bad, loud poping from the exhaust, the tacho was going a little crazy. So I cranked the boost back to stock, misfire wasnt quite as bad, but still present.

I changed the plugs, running standard denso coppers, gapped it .8mm. Misfire went away... at least so I thought.

Last night misfire came back about 2-5 pops in each gear as I went WOT to redline. Not too bad, but its slightly noticeable in the power band.

So today drove her again, misfire is gone.

Now im begining to speculate it is temperature related. Basically I feel my coils are getting old, and getting tiny cracks, and when it is cold at night the plastic sheilding is pulled inward and more condensed do to the plastic being cold, exposing the tiny cracks allowing the spark to not completely arc, thus the misfire.

During the day I think due to the heat and warmer air the plastic around the coils expands slightly closing the tiny gaps, and holes, allowing for the spark to properly be conducted. Thus no misfire...

I might try to wrap them, I see some people use 3m electical tape, and others use this Araldite stuff...

any other suggestions and thoughts?

[rustbucket]

My car did the same thing, had to retard the timing a little more when it got cold.

[rcrdps]

I replaced mine. It was off and on like you said. I bought two coils from Autozone, and just went down the line until it stopped missing. I think it was the 3rd coil from the back. My guess will be it will be one of the middle coils that is bad. They seemed to have the worst heat marks.

Gene

[Carl H]

either coils or ignitor is going bad, if its inconsistent with boost and it doesnt go away after warmup then i would speculate dying ignitor or a coil on the verge of death.

[Shocker]

k, well here is the report, I drove her all day today, no misfire at all. About 25% of the time was spent at WOT as well. Im going to drive her tonight, see what its like in cold weather....

[Carl H]

it could possibly be a bad ect sensor...they tend to do strange things.

[Shocker]

nope, no misfire tonight... it didnt only go down to 50 degrees too. this is very weird.... ECT sensor? that is located?

[Darius]

Engine Coolant Temp sensor is on the intake manifold next to the injector harness clip right on the front of the motor. It's the bigger of the two sensors sticking out of the top of the upper radiator hose connection.

Does the misfire go away after the motor warms up at all?

[Shocker]

Engine Coolant Temp sensor is on the intake manifold next to the injector harness clip right on the front of the motor. It's the bigger of the two sensors sticking out of the top of the upper radiator hose connection.

Does the misfire go away after the motor warms up at all?

oh yeah I know what that is... just always called it temp sensor.... Im sure I can grab one off the dealer, I think ill actually do that today.

The misfire never really seems to come around when its slightly warmer outside.. like above 40-45 degrees.. and the misfire when it happens.. is ONLY apparent at WOT, its smoothing reving under load at another other throttle position... Ill be drivng her more today granted the rain stays away and keep updates comming...

thanks for the responses guys. very weird scenerio to me... I could see if it was consitant lol.