Misfire help

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03-02-2010, 08:40 AM

llonman

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Misfire help

I have searched through the forums and need some advice. Getting misfires, pulled codes a few weeks ago;

16805 - Warm Up Catalyst: Bank 1: Efficiency Below Threshold
P0421 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - Please Register/Activate
16689 - Cylinder 5: Misfire Detected
P0305 - 35-00 - Please Register/Activate
16687 - Cylinder 3: Misfire Detected
P0303 - 35-00 - Please Register/Activate
16690 - Shareware Version. To Decode all DTCs
P0306 - 35-00 - Please Register/Activate
16686 - Shareware Version. To Decode all DTCs
P0302 - 35-00 - Please Register/Activate

Did some research, cleared codes and ran for a day..Codes below.

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16690 - Shareware Version. To Decode all DTCs
P0306 - 35-00 - Please Register/Activate
16687 - Shareware Version. To Decode all DTCs
P0303 - 35-00 - Please Register/Activate

Switched ignition coil to 5 and 2, misfires followed. Replaced ignition coils and car ran perfect for a few hours then started to misfire again under full throttle or load.

Car runs better than before but still misfires under load or full throttle. Runs smooth most times when acccelerating lightly.

4 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16689 - Shareware Version. To Decode all DTCs
P0305 - 35-00 - Please Register/Activate
16686 - Shareware Version. To Decode all DTCs
P0302 - 35-00 - Please Register/Activate
16690 - Shareware Version. To Decode all DTCs
P0306 - 35-00 - Please Register/Activate
Readiness: 0000 0001

Since the misfires are not limited to one bank I guess the controller is not the cause. Mass air flow sensor?

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03-02-2010, 05:36 PM

rs4tech

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when was the last time you replaced the spark plugs, and if so did you use good ones?

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03-03-2010, 05:06 AM

llonman

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Quote:

Originally Posted by rs4tech

when was the last time you replaced the spark plugs, and if so did you use good ones?

30K ago and I cant remember the brand but they were quality plugs. Guess Ill run some of the block tests with VAG-COM and see if MAF or O2 sensors are within spec. Maybe replace a plug and see if the misfire stops on that cylinder.

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