SL-Class (R129) 1990-2002: SL 280, SL 300, SL 320, SL 500, SL 600, SL 60 AMG

SL/R129: Random missfire.

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Old 06-11-2023, 11:47 AM
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Random missfire.

Guys 99 SL500. 138k miles
From time to time, under load I get a miss and a check engine light. I cant duplicate the problem at will.
Restart the car and all is well again.
First the code showed 5 and 7 cyl.I changed coils on that side,
Now it shows again 3,4,5,6,7. Even with new coil packs on 5,7 and new spark plugs all around.

No egg smell. Car pulls hard.

Spark plug wires? MAF?

Why cant the codes be more accurate.

Thanks

Changed plugs which were old, used Bosch FR8DPP33 part number is 7422.
Old 06-11-2023, 01:33 PM
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2017 GLE350 4MATIC
Originally Posted by tbilisi79
Guys 99 SL500. 138k miles
From time to time, under load I get a miss and a check engine light. I cant duplicate the problem at will.
Restart the car and all is well again.
First the code showed 5 and 7 cyl.I changed coils on that side,
Now it shows again 3,4,5,6,7. Even with new coil packs on 5,7 and new spark plugs all around.

No egg smell. Car pulls hard.

Spark plug wires? MAF?

Why cant the codes be more accurate.

Thanks

Changed plugs which were old, used Bosch FR8DPP33 part number is 7422.
Does this engine suffer from oil in the harness from leaking cam position sensors and cam magnets?

Also check grounds on the chassis (body sheet metal) and on the engine to be sure they are not loose or corroded.

Old 06-11-2023, 02:07 PM
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Ill take a look. Thank You
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