Thread: car starts to misfire when gets hot? help!!!!

My car starts to run very poorly and misfires on every cylinder randomly about 3 at a time, it usually happens after about 10 minutes of driving. i have replaced the coils awhile ago, i had zzp wires and just changed those to autolite professional series wires. and i have autolite 605's, aslo i just replaced the icm. i have an aeroforce that tells me the misfires and when its running good it still shows a couple of misfires but i think that is due to the vs cam with no tune, but when it runs like crap it shows anywhere from 45-60. it seems that cylinders 3,4,6 has the most misfires.
I think it has something to due wiht the coolant temperature sensor, but i could be wrong. not sure.

Has anyone had any similar problems or can tell me whats wrong?

Originally Posted by Doug 97 gtp

but i think that is due to the vs cam with no tune

tell me whats wrong?

really...?

If you have an aftermarket cam, you have to set -Engine Misfire- to "No Report" in the pcm. Hope you have tuning software, or know someone who does.

Oh my.

ive got 700 miles on the new motor and its just now starting to do it!?!?! what the cam decided to play games with me now. i had no problem before

the only tuner that i know of is in daytona... how the hell am i going to get my car there

The last vs cam I tuned did not set the misfire code until we loaded one of the last files. We were starting to think we didn't need to remove it.

i did a little more testing and it seems that i have a bad coil. because the car only misfires when it gets warmed up and its not the plugs wires or the icm. after testing the coils i want to say that thats the problem.

Hopefully it's just a coil since it seams really hard for you to get your pcm tuned.

Good luck and keep us updated.

Hope you don't have the metal heat shields on the plugs. If so take them off.

i dont. i got some new coild today and will be putting them on tomorrow hopefully my misfires will go away

If your engine temp sensor is old it wont hurt to replace it, I have heard of faulty temps sensors causing misfires.

well i replaced my coils and the car still does it. now i have moved to think that it may be my map sensor because the misfires come and go