another rough idle misfire thread HELP!!!
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Senior Member
Joined: Mar 2012
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From: TEXAS
another rough idle misfire thread HELP!!!
I am at a loss at this point, in more ways than one. I chased an intermittent misfire for weeks and found out there was a short in my main engine wiring harness, causing major major misfires, I mean this thing barely ran. I replaced the harness and it is almost back to normal, except a slight misfire at idle with code p0301. I have cleaned my MAF and throttle body, I have replaced the erg, as well as the tube, I have replaced all spark plugs, as well as coil boots. I have swapped coils and injectors around, and I still get a p0301. I know I am getting spark to the spark plug after testing it, I am getting around 13 volts to the injector, and have tested and confirmed the cylinder for compression. What in the world else could it be?
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From: The City of Oranges,FL
I am at a loss at this point, in more ways than one. I chased an intermittent misfire for weeks and found out there was a short in my main engine wiring harness, causing major major misfires, I mean this thing barely ran. I replaced the harness and it is almost back to normal, except a slight misfire at idle with code p0301. I have cleaned my MAF and throttle body, I have replaced the erg, as well as the tube, I have replaced all spark plugs, as well as coil boots. I have swapped coils and injectors around, and I still get a p0301. I know I am getting spark to the spark plug after testing it, I am getting around 13 volts to the injector, and have tested and confirmed the cylinder for compression. What in the world else could it be?
http://repairpal.com/OBD-II-Code-P0301
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Joined: Apr 2015
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I had a misfire that coded and it turned out to be a bad spark plug wire that was almost burned in two by the ERG tube being so close to it. The insulation on the tube was moving to the side allowing heat to direct itself on the spark plug wire. Insulating the tube along with replacing the spark plug wire solved the problem.
Hope this helps. Good luck.
Hope this helps. Good luck.
I am at a loss at this point, in more ways than one. I chased an intermittent misfire for weeks and found out there was a short in my main engine wiring harness, causing major major misfires, I mean this thing barely ran. I replaced the harness and it is almost back to normal, except a slight misfire at idle with code p0301. I have cleaned my MAF and throttle body, I have replaced the erg, as well as the tube, I have replaced all spark plugs, as well as coil boots. I have swapped coils and injectors around, and I still get a p0301. I know I am getting spark to the spark plug after testing it, I am getting around 13 volts to the injector, and have tested and confirmed the cylinder for compression. What in the world else could it be?
Last edited by techrep; Apr 24, 2015 at 06:45 AM.
Thread Starter
Senior Member
Joined: Mar 2012
Posts: 523
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From: TEXAS
wavector- I just replaced the main engine wiring harness I.e. the plug wires last week. lol so I am eliminating short
techrep- I'm just gonna buy a new plug and coil, just to be absolutely sure, but wouldn't the compression test eliminate the internal problem,such as a bent valve?
techrep- I'm just gonna buy a new plug and coil, just to be absolutely sure, but wouldn't the compression test eliminate the internal problem,such as a bent valve?
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"I have swapped coils and injectors around, still the code". Plugs are known to be bad right out of the box. I would start with just the #1 plug replacement. If it was the COP, when switching #1 to another cylinder, the code would have moved with it. I think you have narrowed it down nicely to plug #1.