This service bulletin warns owners with ZF automatic transmission not to raise the idle in neutral while undergoing smog tests, a/c recharging, injector cleaning, and other necessary services. The bulletin applies to E24 years 1984-1987. We own a 1989. Did BMW correct this problem or should we also follow the specific recommendations? Here's the bulletin: BMW NA service bulletin # 24 01 91 (3196) dated June 1991 Subject: Transmission Failure during Exhaust Emission Testing Models: All 1984, 1985, 1986 with 4-speed automatic transmission, 1987 635CSi, 735i, and L7. Situation: There have been reported isolated cases of automatic transmissions failing during a High Idle Exhaust Emissions Check. The failures have resulted from a preconditioning procedure where the engine is held at high rpm for a prolonged period of time. The following applies to all states which have a High Idle Exhaust Emission Check. As the internal transmission components experience normal wear over time, the possibility of transmission damage exists if the vehicle is operated for extended periods of time at high rpm in PARK or Neutral. Such operation does not constitute normal operating conditions. If, in exceptional cases such as A/C recharging, injector cleaning, charging system tests, or emissions testing, vehicle operation at high rpm in PARK or Neutral is required the following setup procedure must be performed prior to beginning such operations. Solution: The emissions test must be conducted with the engine at operating temperature. If the engine is not at operating temperature prior to beginning the test, it is recommended that the vehicle be driven for a short period of time to bring the engine to operating temperature. DO NOT run the vehicle at high idle to achieve operating temperature. Once the engine has reached operating temperature, the following pretest procedure must be performed BEFORE testing begins. Setup Procedure for I/M Emission Test 1. Shift to PARK. 2. Turn engine OFF. 3. Wait at least 30 seconds. 4. Restart engine, LEAVE TRANSMISSION IN PARK. After the engine is started, DO NOT move the gear shift selector through the Forward or Reverse gears before or during the test sequence. DO NOT EXCEED 2000 RPM. 5. Begin emissions test procedure. 6. If the vehicle fails the emission test, some states allow for an extended pre-conditioning before the repeat test. In this case the following procedure should be adhered to. Precondition Procedure 1. Shift into PARK and turn the engine OFF for 30 seconds. 2. Restart engine, LEAVE TRANSMISSION IN PARK. 3. Engine may be preconditioned at a maximum of 2000 RPM for up to 90 seconds, at which time the repeat test must begin. If the above steps are not followed, serious transmission damage can result. Note: Due to the unusual nature of the emissions check, this type of failure does not take place under normal operating conditions.
Can't say if they ever did fix this issue or not. To be safe I would just follow the procedure this bulletin BMW doesn't even have in there data base for technicians any more.
