2004 530i E60 M54 automatic
115k miles
1.) When I let off the gas and the car is coasting (at almost any speed, but always happens above 40 mph) and I don't apply any brakes; when the RPM reaches ~1100-1400 the motor will bounce/hit a harmonic, jumping 200 RPM up and down always between the ~1100-1400 RPM. If I apply brakes or a small amount of accelerator the engine stops bouncing around RPM. This has been happening for about 6months.
2.) About 2 months ago I began having acceleration issues. At about 2500 RPM the motor will hesitate and bounce RPM when applying moderate gas. If I give it more gas the hesitation disappears and the motor accelerates strong. I have noticed some decrease in mpg.
For problem (2) I have found that this can be caused by the vanos (variable valve timing) seals can cause this problem and there is a fix for this:
http://www.beisansystems.com/index.html
The computer isn't throwing a code causing a check engine signal.
- I've cleaned the ICV (idle control valve) and it seems to move very freely when shaken back and forth.
- Changed the CCV (crank case ventilation valve) and all associated hoses.
- Replaced the DISA valve.
- I've looked for vacuum leaks by spraying carb cleaner near hoses, no fluctuation in RPM
- Spark plugs have been changed.
- Air filter is free of debris and clean.
- Looked at MAF (mass air flow sensor), it was not clean but cleaned it anyway
- Don't seem to be any crack in rubber hoses
Please help before I spend way to much money to have it diagnosed and not find the real problem.