Engine pinging or knocking?

Hi All, I'm new to the board and I have two BMW's. '88 535i and a '90 735i. The E32 has a engine noise or pinging/knocking in the front of the engine. Has 160k on the engine. I have an O2 sensor code flash and I have a oil level sensor indication on the cluster. Any relationship with the noise? It also sounds like pre-ignition but only in one cylinder. Any help would greatly be appreciatied. Thanks, Mike


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'88 535i 198k
'90 735i 160k

Hey all, Took the engine appart and found #! & #2 pistons to be badly scored. Oviously it had a bad overheating problem in the front of the engine. Found chunks of carbon lodged in some oil jakets and lots of stopleak in the water jackets. The piston is aluminum and could not suvive the excessive heat and therfore started to breakdown. Thank God the cylinder walls mic'd out good and did not suffer. Good ol' iron block. Intake was full of carbon and I could hardley see the pintles on the fuel injector as well. Bad stuff. I put som low time pistons in with new rings and rod bearing (egine still in car) @160k & been runnin like a champ. Mike