This vehicle had a lot of problems with wires. I found some wires chewed up by rodents.. You can imagine what came next.....
2012 SLS AMG M159.980 A/T
Frustrating and sad story short:
Vehicle have misfire on cyl #7 while idling. after 2300 or 3000 rpm all the faults goes away.
Spark plugs: REPLACED (8)
INJECTORS: REPLACED (8)
Coils : REPLACED (8)
No improvements or changes whatsoever...
After finding chewed wires and looking closely every single inch of the engine harness a new one was ordered out of the dealer.
Engine Harness: REPLACED
Looking at Lambda values while idling I found UPSTREAM LEFT SIDE o2 sensor not working. So I ordered a new one.
While replacing the old O2 sensor I found on left side that upstream was wrongly installed on DOWNSTREAM position. So I change positions and replaced the upstream 02s anyways..
Customer tell me that the ECU was replaced by dealer, so I run a follow up after ME replacement.
No big changes on the CYL #7 misfire.
After checking LIVE DATA - FAULT COUNTER cyl#7 shows misfires at idling engine speed, but revving above 2600 RPM all the faults counts goes to 0.
COMPRESSION TEST SHOWS NORMAL VALUES
So, I eliminate fails from Coils, Spark plugs, Injector, wire harness, 02S.
What else do you guys recommend to look at it?
Find attached 2 short videos. AFTER 02sensor replaced.
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