As my 1991 735i is drive by wire (EML) I took it to my local BMW Tuner, Miller Performance, and they traced it down to the EML system with a code reader, but it wouldn't tell you anything further than that. The EML throttle body is only receiving 3.3V, and if you look at the throttle plate it is only opening at approx. 1/2 way, when you have the accelerator pedal at full throttle. This explains the driveability problems I am having. The throttle body is also not very responsive to the movements of the accelerator pedal.

So, luckily the brother in law of the owner happens to have an EML 535i, so he swapped in that throttle body to hopefully narrow it down and that throttle body reacts the same way, which is a mixed blessing because those are very rare used and damn expensive new!

O.K., so it can be narrowed down to the EML module or the pedal potentiometer, correct? The Bentley lists the voltage at full throttle at 3.7-3.8V and mine is only reading 3.3V. Also I should add that the tranny kickdown operates at the correct position.

1)Would this 0.4-0.5V be enough of a difference for my lack of opening?
2)Would this be the result if it is out of adjustment, or is it an internal problem with the potentiometer?
3)Can the potentiometer be opened up and cleaned like a auto transmission gear switch?
4)Is there anything else that I can check?

I did a search for pedal position potentiometer on this forum and a few posts mentioned that if this part is bad the car simply won't rev. This confirms my suspicions and symptoms. Dan at Miller Performance also said that the EML control modules rarely go bad so I doubt I have any other options.

All comments, suggestions, and experiences are welcomed! Thanks.

Cars = 05/91 735i, 189k km's; 03/90 325i 278k km's.

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            • UPDATE: Narrowed it down to the M30 EML system - whiteghost 2008-08-09 21:11:28 (30 views)