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Old 03-04-2003, 01:36 PM
Posts: n/a
Calibrating the Mixture on a 16 V

I have been struggling with my cars drivability for the last 8 months after replacing my car's potentiometer to fix a stumble on acceleration. The stumble ended up being a defective distributer cap so I reinstalled the original pot after cleaning it with alcohol.

When reinstalling it the only procedure check that I have was to get the unit to increase continuously to approx 5 volts when the sensor plate is deflected, per my MB manual. Is this critical? If so why does my CD rom manual so vague?

Since this time I have been unable to get the car to idle reliably. Sometimes it idles fairly good with just a slight dither between 950-1100. Other times it will stall repeatidly at idle. Still other times it hangs at 2000-3000rpm. I am very suspect of the CIS control unit being bad from my tinkering, but based on some of the other posts I am not alone in my problems. So maybe the Control Unit is OK, just the system is out of adjustment.

I took the car into a shop to fix and they simply drilled out the mixture adjustment plug and tampered with that and then concluded that they could not fix it either. Now I have no idea what is right anymore.

I do have the MB manual and have checked a number of the devices and have found everything to be within spec in terms of resistance values and the EHA when checked seemed to be at the proper duty cycle at idle.

The car is currently running rich based on fuel mileage 17mpg and black soot coming from the tailpipe. but when I adjust the mixture screw the idle has a tendancy to oscilate violently and stall repeatidly.

Currently I have my multimeter hooked up to the O2 sensor and am curious about the signal from that. Once the car warms up the signal is around .8-.9 volts most of the time, but then occasionally it will oscilate from .1 to .9 as I think it should but then a few minutes later it again hangs at .8 or .9.

Any suggestions would be appreciated.

Last edited by zeilekd; 03-04-2003 at 10:59 PM.
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