My 89 325i (ZF 4HP 22 Transmission) with 116,000 miles shifts late out of first gear under normal acceleration after the car has sat for a few hours. Almost always, the car nearly red lines in the morning just to get it out of first gear. Then, it usually skips second gear and goes right into third gear.
Once it has shifted out of first once, it's usually fine and drives semi-normal after that until the car sits again.
I drained the transmission fluid and put a new tranny filter on the other day. The magnets had very little build-up, and the build-up that was there was extremely fine. So, it doesn't appear to have any internal damage. However, is there any way I would know if there is an internal leak? (There are no external leaks) The old filter did appear to be pretty clogged. After replacing the filter and re-filling with Mobil 1 Synthetic ATF the car was driven for a good half-hour with great results. The tranny shifted very smooth and was responsive at all speeds.
After the car sat for about 2-3 hours, it was driven again and the transmission did not shift out of first gear until it reached very high RPMs. It appears the filter change and fluid change did not fix the problem.
I guess one idea is that the fluid that could not be drained out of the torque converter had so much crap in it that it clogged the new filter after the new and old fluids mixed. Is this a possibility?
Other ideas I'd like to know more about:
Could it be solenoid related?
The car has a performance chip...could a faulty performace chip cause these kind of shifting problems? And, can I pull the chip and see if shifting improves? Do BMW chips piggy-back on stock equipment, or is there a stock piece removed when installing the chip?
Is there anything else I can do? I'm getting ready to move and I need to sell the car, so I'd like to have it in good mechanical shape.