I have an 03 evo and at idle with no load it misfires. CEL is always on. Spark plugs and wires have been changed. So have the vacuum line to the fuel pressure regulator. Been to the dealer a few times they couldn't figure it out. It have been reflashed twice. Only mod is a catback exhaust. Only suggestion from the dealer is a hollowed out cat. Everything else I was told tests out fine. I can feel the misfire on cold and warm starts it doesn't matter, any suggestions?

 

Also the rpm guage say it idles at about 100 rpms but the car don't idle that horribly. It is missing however.

 

well u need to hook up a scanner and data stream the misfire monitor and see which cylinders are misfiring. then you go from there. could be many things like a bad injector, or a coil pack. or something really simple.

 

The exact cylinders can't be pinpointed. Its random, multiple. The coil packs tested out fine. As for the injectors i tapped on them to try and unstick them if they were at all. I also had my fuel injection system cleaned

 

Have you changed anything at all before this issue appeared?
Has your ecu been flashed for the p0300 fix? There are 2 of these for the 03's.

 

whats mods do you have done???

 

I have a 05 and have the same problem. I noticed it a couple months after i got the car. Basically when the car is fully warm the car has random stumbles/ hesitations at idle/low RPM's in neutral. I can feel the engine shake for a split second and hear a disruption in the exhaust tone. I thought something might have been wrong but when driving the car everything is normal and I have no loss in power. I was listening to an exhaust video clip the other day of an evo (not sure what year) and that car had the same “stumble” I had when the car was idling. Other people have told me already not to worry about and that its normal. Its been doing this for about a year now and has gotten a little but worse but don’t notice anything being effected besides ME wondering what the hell is causing it lol. The only things I could think of causing the issue would be an ignition or computer problem. Im not going to worry about it but I hope someone finds out the cause.

 

a friend has a srt4 and his does it but he said its the throttle position sensor going bad. mines doing it as well

 

mine used to throw the code but i never noticed it missing at all..... *knocks on wood*

 

Yes I have been flashed twice to no success.. I haven't changed anything before this problem happened.

 

The only mods are a megan catback exhaust which was on before the code and a greddy turbo timer which I installed after I was getting the code.

 

anymore advice guys?

 

You guys aren't alone I get a random misfire also at idle sometimes. I started getting them more often after I started to use the ngk bpr7es plugs gapped to 26. Today I put my stock plugs back on to see if it helps since it didn't do it as often when I had them on.

 

Do a compression test, make sure you don't have bad compression, and at the same time inspect your plugs. Go to autozone and get a free scan to see what code is actually being thrown.

 

The code is P0300. I've done a compression check already also. Readings I believe were about 170 or 175 across the board. I don't remember the exact readings right now. All cylinders were the same though. Plugs were put in by a dealer and re-gapped by another.