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Re: Update on Weird Motronic/M30 3.3 engine (archive)

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Posted by Bob on June 23, 1999 at 02:06:37:

In Reply to: Re: Update on Weird Motronic/M30 3.3 engine posted by bill on June 19, 1999 at 15:49:34:

: can you go back to the source of the 5 volts and find out if it is there, like you may have a bad wire/path.
Unfortunately, the Bently manual shows no connections to the idle switch contact except the idle speed computer and the Motronic box, and both were checked by substitution. Whe the computers were pulled, the resistance to ground for this contact was infinite.

I have installed a 6.2 volt zenier diode from the fuel pump relay to the idle contact (to make the computer see around 6 volts and thereby run in the main computer, not idle, mode), adjusted the idle switch always open, removed and plugged the idle speed compensator circuit at both ends, removed the ISC, and set the idle with the throttle butterfly. I know this is a no-no, but the car runs great except for having to hold some manual throttle for 30 seconds after cold starts (no fast idle cam).

I know this is butchery, but the car now runs great.

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