When I read duty cycles from pin 3 at the diagnostic port there's a very strange thing happening. With KOEO I get 85% on a frequency of 100hz (California car). When I start the car the duty cycles go all over the place and the frequency jumps to approximately 500hz +/-50hz. And here's the strangest part: as the RPMS increase so does the frequency, up to around 1500hz @ 2500 RPMS. This happens when the multimeter is grounded on the chassis or on pin 2. This also happens when I bypass the OVP relay. At KOEO a deflection of the air sensor or the throttle does not cause the duty cycle reading to drop to the designated 10%. I tested the TVS and the air mass sensors and they are to spec.

I believe the car is actually running with the Lambda to spec as the amps on the EHA dance around 3ma and the readings on the O2 sensor are between .1 and .9 volts.

I have another W124/M103 that reads appropriatly. I'm not above swapping parts until the answer is found .

Any ideas? I am clueless...

Thanks,
Robert

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89 300te 222,222
92 300e 190,000