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2000 BMW 528i – M52TU, M54 Engine Stalling at Cold Start – E39, E46, Z3, Z4, X3, X5

October 4, 2010

Q I have a 2000 BMW 528i well serviced and in excellent condition but recently I experienced the following problem that the BMW service cannot identify or fix.
Observations:
When I start the car, cold in the morning, the engine starts and idles fine. I drive and if I stopped in traffic light during the first mile or two within the first five to eight minutes the REVS drop / fluctuate to stall. I start again and it works fine and do not have any problem at all until the next morning! Also, When I start the car in the morning and do not drive, but leave the engine running for about five to eight minutes the engine REVS drop / fluctuate to stall. I start again and it works fine and do not have any problem until the next morning! Note: I use different brands of highest-grade gasoline and use BMW fuel injector cleaner every six months. Please let me know your diagnose of this problem.

A
Have you checked if there are currently any engine management fault codes stored? If there are, they may help direct our diagnostics. We do offer a tool that will read and reset the codes, as well as reset the oil change and service/inspection reminders.

Code reader/reset tool:

* You should clean the Mass Air Flow sensor (MAF). Remove the Mass Air Flow sensor (MAF) and clean it. Purchase a can of CRC-brand Mass Airflow Sensor Cleaner. Spray the hot-film sensor in the middle of the MAF. This is the shiny plate in the airflow area of the sensor. Spray it liberally, from all directions, let it dry and reinstall it.

If we have no helpful fault codes AND cleaning the MAF does not help, you may be dealing with vacuum leaks, a clogged crankcase ventilation system or a faulty VANOS control unit.

* You may have a problem with partial clogging and/or deteriorated hoses in the crankcase ventilation system. This is VERY common on these engines. We have issues with the system clogging with oil sludge (due to long oil change intervals and condensation), as well as deterioration of the hoses which creates vacuum leaks. In order to replace the hoses and oil separator valve, the intake manifold must be removed. We do offer a complete kit that has all of the parts included. See the blog post at  THIS LINK.

Failure of the internal piston seals in the VANOS unit (the variable cam timing control unit) is becoming common and the symptoms that you’ve described are common symptoms for this fault.

VANOS unit:

Obviously, there are other possibilities, but without having the car here to test and diagnose, these are the initial suggestions.

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