Join Date: Apr 2011
Location: Destin, Florida
Vehicle: 2000 SLK230
Other Toys: 2006 Hummer H3
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Cylinders 1 and 4 not always firing
For the past month, I have endured a rough running engine due to cylinders 1 and 4 occasionally not firing. Sometimes, I can turn the ignition off and restart the engine to clear the problem.
So far I have: Ran Injector cleaner through the last two tanks of gas, cleaned the MAF ( I replaced 1 year ago), replaced the fuel pressure regulator, fuel filter, fuel pump and Throttle Position sensor. 1 year ago, I replaced the sparkplugs, coils and both O2 sensors. I have disconnected the battery twice for over an hour each time.
What could it be?
I get 5 codes indicating O2 failure, misfires on cylinders 1 and 4.
I'm thinking I may have to replace the ECU.
You suggestions are greatly appreciated.