goldendd

P0307 Cylinder Misfire...Now that I know what it is, what is it? Misfire? Is it an injector, spark problem, how do you diagnose further? Just got a 2000 GT Convertible 4.6L 5 Speed today and the check engine light came on.

I G Joe

welcome to the forums and congrats on the car, sorry about the CEL. it could be a matter of things, run some injector cleaner through the system, replace the fuel filter if it hasnt been replaced recently, and check the spark plugs.

Edit: are you asking what may cause a missfire or what is a missfire?

goldendd

Thank you. Yes I know what a misfire is but I want to know what is causing it. My code reader just says misfire in #7 cylinder. I thought about putting some injector cleaner but the misfire feels electrical.

I G Joe

could be a bad spark plug then. im not sure how it would feel "electrical" but im trying to keep an open mind and understand what you are saying.

is it constant though can you feel the missfire?

how does the car respond to WOT runs or throttle blips?

start off with some injector cleaner and a fuel filter, those are two things that should be done anyhow.
if the problem doesnt change i would check the plugs,coils, and boots.

Brute03

if the misfire gets worsewhen you put your foot down at low revs then it's more than likely spark-related. replace the #7 plug then see if it still misses, if it does, your COP is probably done..... quite common on these cars

baino

Had the same problem. I went ahead and swapped all the plugs and COP's. Cleared it up and is an easy do it yourself job, but as always a lil costly.

goldendd

Thank you guys for all your help and suggestions. I pulled all the injector wires off one by one until there was no change in the idle. I replaced that spark plug and it corrected the problem. The plug I pulled out was in very bad shape which makes me think the previous owner had somthing against tune-ups. The car runs much better now and I am planning a complete tune-up in the very near future.

I G Joe

somethin you should do with any used car you buy, even if from a dealership.

naza

hey guys im going to hijack this thread jaja...

i just had the same problem today!! took it to autozone to get the code and i was po3o6...

the weird thing is that i just did a tune up to the car about 2 months ago...

my question is... can it still be a bad plug or a bad cop/??

thanks for the help guys!

oh yeah it also threw the o2 sensor code but that has been on there since i put my x-pipe on..

ct_white_stang

OP - Make sure you torque down the plugs correctly. Do yourself a favor and do a search on spark plug blowout on here...