HELP!!! E39 03 525i RPM bounce rev up and down while driving at certian speeds
Car: 03 525i 150,000 miles
Symptom: At various speeds I will notice the RPM bounce at about 1200 to 1500 back and forth, making the engine rev up and down. This occurs at a constant speed and generally on a slight incline or stress on the engine. You can simply apply more pressure to the pedal which will increase RPMs and it goes away. It is more noticeable at approximately 42mph with a steady foot on the pedal trying to maintain this constant speed, add a little incline it will rev and up and down constantly. I can get the car to do it at lower speeds but it is harder to maintain say 20mph than a consistent 42mph. I have at the shop several times and no one knows what to do. Here is what has been done and checked.
1. MAF - no difference
2. DEESA - no difference
3. Spark plugs all replaced, (needed to do it anyway) COILs are OK
4. Had oil pressure lines replaced two years ago when replaced the Oil housing gasket was done.
5. Smoke test revealed. Had crankcase vent valve and hoses/pipe replaced
6. O2 Sensors replaced at 110K
The first shop could not figure it out as there were not error codes tripped and no SEL and the tech is very good. But not trusting he is perfect, took it to the dealer, and they couldn't find anything. The first day, he said I had a misfire on COIL 5 and plugs needed to be replaced. I told him, that was not causing the problem but he responded, I cannot proceed without first fixing that. Asked $540 to fix. I said, no, replaced the coil and plugs in 30 minutes for 1/4 of that. Problem stayed the same. Took it back, and as they tell me I need a new transmission, no explanation other than we used BMW tools to figure it out. My guess is since there were no error codes or SEL on, the tech did not know how to troubleshoot and throws back a $5800 transmission bill at me to make me go away, knowing I won't fix it at that cost. Also, temperature has not impact, can replicate 100% of the time.
I love this car, maybe it is time to put it to rest. Would have like to keep in for another 50K and pass it to my kid. Is it really the transmission? I searched the forums for hours with no luck. Here is what people suggest:
1. TPS or Throttle Bottle
2. Crank or Cam Position Sensor
3. Vanos ?
Last edited by BruiserBob; 02-08-2013 at 06:05 AM.