BMW M52TUB28 engine details

(Dual infinite variable Vanos, Siemens MS43 ECU, 1998)

It is very similar to the later M54B30 engine


This engine has 3 HALL sensors:

Scope shot of crank+intake cam trigger:


It has a weird distribution at the missing teeth, not really 2 missing, but 0.5 missing and then 1.5 missing.

This HALL pattern looks perfectly OK (57*1 + 3 long gap) with primtrig=falling selected.

Same measurement apparently captured with primtrig=rising : Confirmed, it was.


from [triggerlog]

With this pattern, using normal 60-2 trigger settings in firmware 1.2.31 is hardly recognizing any movement of the engine -while it was running nice with the stock ECU. However, Advanced Filtering with the normal tooth limited to 25-156% and missing tooth to 163-338% seems to cure this problem:


Engine is running flawlessly with the settings above :)

-Thanks to Marcell for the quick support!


This engine has a very special cable AND motor driven throttle body, looking like this:


I guess it's a shy approach from BMW to change from cable to electronic... Mostly it operates on cable drive, but the butterfly is connected through a spring - not the rigid axle, so the electric motor from the other side can alter the position in the event of wheels spinning. Apparently it is also smoothing throttle response after a lift off from the pedal.

It's working OK as long as it is driven by the factory ECU, but the TPS potentiometers resistance (and voltage) is not giving enough resolution to VEMS to handle it properly.

I measured a change of 1.3KOhm to 1.8KOhm during the whole movement of the throttle plate. /on both TPS pots, because there are two of them in the housing/

With these values, giving a very slight throttle opening at idle results in rising to 3000-4000rpm, without a 0.1% change in TPS signal.

It makes VEMS idle function useless, and I'm looking for a solution -apart from changing this throttle body.

First: report exact voltage and calibration values. (and try pullup resistor, maybe needed; perhaps even a 4k7 makes a huge improvement)