Confused with P0300 code

[GSXRRocker]

Ok, so I'm working on my mother in laws 03 sunfire. She bought the car about 8 months ago, but hasn't put more than 4k miles on it. The car was neglected as far as oil changes goes, think it was around 5k miles since last oil change. The car started running rough, it doesn't stall, but its close to it. I checked the codes on it and it threw a P0300 (random misfire) and the code for a bad cat. I replaced the upstream O2 sensor and the cat code went away, it ran a little better, but was still very rough. I changed the oil and spark plugs and both individually improved how it ran, but its still rough. When I changed the plugs #1 and #4 were rich (possibly fouled). After research I found the coil packs frequently cause this issue, I replaced it but no difference so i returned it and installed the old one.

Instincts tell me that if the module were bad, it wouldn't throw spark at all, but I could possibly be wrong on this. I doubt its injectors as its running very rich, not lean. I checked the vaccume line from the charcoal canister, but didn't find anything there, it sounds like theres a vacuum leak coming from the power steering pump, but couldn't locate the source. I'm also assuming that if it were a vacuum issue, it would create issues for all four cylinders not just 1&4. I thnk i'm going to go check the compression on it, as i'm lost as to what this could be, and excessive oil blowby could cause it.

any help would be greatly appreciated.
Oh, sorry this was so long, I tend to ramble

 

[GSXRRocker]

*bump*

I have since checked the compression and it ran around 170 psi across the board, checked the electrical pulses to the injectors and that checked out, pulled the fuel rail and injectors and they seemed to be spraying equally and evenly across the board.

I'm still lost on this

 

[Zimgxp]

Try replacing the "coil mounting bracket". Its the part that delivers the spark from the coils to the plugs. This is assumeing you have the 2.4 motor.

 

[planenut_2000]

If you have no spark from the 1-4 coil pack it's either the module or coil. you can test the module by removing the coil that won't fire and put a 12v test light across the 2 terminals. if it flashes then the coil is bad, if it doesn't flash then the module is bad.

______________________________

 

[Dual Bro's Auto]

Re: Sorry for re-opening the thread

I had the same problem just recently on an 04 Sunfire where I got the P0300 misfire code but my scan tool was not equipt to tell me which cylinders. Regaurding the ignition control module, there are actually two drivers in there and one can go bad and the other can be functional. I actually just shot a video of testing procdures for anyone else that has this issue https://www.youtube.com/watch?v=dtNQWj26RNU

Hope this helps!

 

[EaOutlaw]

I had the same problem just recently on an 04 Sunfire where I got the P0300 misfire code but my scan tool was not equipt to tell me which cylinders. Regaurding the ignition control module, there are actually two drivers in there and one can go bad and the other can be functional. I actually just shot a video of testing procdures for anyone else that has this issue https://www.youtube.com/watch?v=dtNQWj26RNU

Hope this helps!

First off I want to say thank you for sharing this video and your findings.
And welcome to the forum.

With informational videos such as yours you may want to start your own thread, this will make it easier to find the video. it will get more views and likes.

It would have been nice to see the actual test before and after the new ICM was installed so the person needing the help can see what your talking about.

I will ad the video could be more informative because a bad crank sensor or intermittent bad connection at the crank sensor could also cause both of the two connections at the ICM not send a signal to the coils to fire.

I know and you know that a crank or cam sensor will have a associated code in the PCM yet not all of our members are as mechanically inclined as you,
So it is best to include as much information as you can to avoid misdiagnosing the problem.

Diagnostic procedures and flow charts to properly diagnose this or any modern car truck or van can be found in any good factory service manual.

It is my opinion that these how to videos are great when paired with a good service manual and the correct tools. again thank you for sharing.

Alldata diy and mitchell1diy both have online versions that are subscription based.

http://www.alldatadiy.com/?gclid=CPvYsJjS8MoCFdCRHwoddv0MgQ

http://www.eautorepair.net/app/YearsMakes.asp?gclid=COreyonS8MoCFUQkhgodyvoAxA