severe pinging

[dickvandevelde]

My friend's 2001 GS has severe pinging. It has high test fuel and new fuel filter and runs great. It'll walk away from my R100RS. It has slight ping under half throttle in all gears and it gets worse as you go in higher gears. It gets so severe you back off, it's like a hammer in there. The left cylinder sounds louder to me. Where do I start looking, could a TP sensor be adjusted to minimize this? I'm a 1000 miles away from a BMW dealer. Got any good ideas? Dick V.

[Major Softie]

Well, obviously we're a little late here. My first guess would be a temp sensor, but it could be major brain issues. Does that model have a "limp home" mode? If so, I'd do what ever triggers that.

[dickvandevelde]

thanks for your comment Softee. This bike does not limp home, it has lots of power so that mode has not kicked in if it has it. The problem only happens when trying to pass a semi or something.
I talked to a BMW manager and he said the motor has too much carbon; does not make total sense since it pings worse before the motor gets up to operating temperature. I do not fully understand injection system on the bike. How does the processor know how much air goes through motor to adjust pulse width and spark timing by just using air temperature and oil temperature and throttle position? Maybe sensor is in error.
I have no scan tools. On cars they have map or maf sensor to accurately measure air flow through the motor.

[Major Softie]

thanks for your comment Softee. This bike does not limp home, it has lots of power so that mode has not kicked in if it has it. The problem only happens when trying to pass a semi or something.
I talked to a BMW manager and he said the motor has too much carbon; does not make total sense since it pings worse before the motor gets up to operating temperature. I do not fully understand injection system on the bike. How does the processor know how much air goes through motor to adjust pulse width and spark timing by just using air temperature and oil temperature and throttle position? Maybe sensor is in error.
I have no scan tools. On cars they have map or maf sensor to accurately measure air flow through the motor.

The O2 sensor sees what the gas levels are in the exhaust and then adjusts accordingly. It gets its starting point by the ECU looking at air temp and engine temp, but as soon as it starts, the O2 sensor can send more info.

My '96 used an open loop until it hit operating temperature (didn't adjust the mixture according to O2 sensor readings until up to full operating temp), but I don't know if his later model is exactly the same.

Carboned up cylinders would be worst when hot, and the richer mixture when cold would probably prevent it during warm up. I agree with your "doesn't make total sense." A too lean condition at all times would do it, and a bad temp sensor telling the computer that the engine is warmer than it is could cause similar symptoms.