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-   -   P0304 Misfire Code. (http://www.yourcobalt.com/forums/problems-service/31884-p0304-misfire-code.html)

Coby7 04-05-2013 05:24 PM

Anything ???

dthammond 04-06-2013 06:25 AM

Thanks for the info, to all of you. I haven't had a chance to do anything to it yet but will hopefully work on it this weekend. Coby7, you might be on to something. My wife told me that a few times she didn't think the car was going to start, turn over so it may be voltage (battery related) Will def look into that. Thanks again and will post my findings!

Coby7 04-06-2013 06:30 AM

If battery reaches under 11.8 Volts while running it gives all kinds of ghost codes and problems that aren't really there.

dthammond 04-06-2013 06:34 AM

You say it will give ghost codes but will it also make it not run correctly? It runs great until you are idling or in park and then it idles rough.

money_man 04-06-2013 07:04 AM

Those are the times the alternator is putting out its lowest voltage so that would be the perfect time for a weak battery to show itself.

Coby7 04-06-2013 03:09 PM

Quote:

Originally Posted by dthammond (Post 619405)
You say it will give ghost codes but will it also make it not run correctly? It runs great until you are idling or in park and then it idles rough.

Almost like a snowball effect. "Let's say your throttle body is a bit dirty and makes your car idle rough, then your RPM fall below the alternator thresh hole then voltage drops, then MAF sensor loses it's calibration making the engine run rougher and the ECM trying to compensate by opening throttle which in turn revs up RPM which kicks in the alternator which changes the MAF calibration again because voltage came back up so ECM cuts fuel and engine RPM drops again and the vicious circle starts over." A good battery will keep all the sensors at calibrated voltage and save you a lot of headaches.

Try borrowing a known good battery and do the exchange and see what happens but make sure your throttle body is nice and clean first so your not chasing your tail.

dthammond 04-06-2013 03:18 PM

Thanks Coby7 and Money Man. Will try that and let you know.

dthammond 04-14-2013 07:16 AM

Well, it's not the battery or alternator. Voltage when off is 12.69. Voltage with no load, 14.920 and loaded 14.580.

Any other suggestions? Someone mentioned I may have a burnt valve in #4. Thought about this, but want that to be a last resort if so because of the expense.

Coby7 04-14-2013 07:28 AM

You said you did a compression test...Burnt valve would have showed up. But you never answered whether or not you cleaned the throttle body or if you even checked it.

dthammond 04-14-2013 11:00 AM

Haven't done that yet, sorry forgot about that. That will be next then. Yeah, did a compression test. That was fine. But this mechanic that I spoke to said it still could be a valve with a good test. Didn't sound right to me though.


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