Irregular idle

What type of 328? K-Jet with Lambda or K-Jet without Lambda?

 

I was just getting ready to post the same question as I'm having a similar problem with My 88 Mondial. I believe mine is Lambda. Any advice would be great. Thanks,
John

 

I should have also asked if the unsteady idle occurs when cold or warm or both.

On the "with Lambda" systems, if the cold idle is steady and the warm idle is not steady, an easy first test is to just unplug the O2 sensor and see if the warm idle is more steady when running open-loop.

 

On my Mondial the idle seems to jump around more when it's hot. 91tr are you thinking perhaps it could be an 02 sensor going bad?

 

While my 328 has not done it, I have another car with CIS injection by Bosch that did. It was my 1980 450SL. The systems are quite similar. What cured it was to remove all the deposits around the periphery of the flapper valve in the air intake. These cars have the 'barn door' type of system for measuring air flow. At idle it is a close fit where the disk meets the venturi. If there is buildup around the disk, the idle can fluctuate. I used carburetor cleaner on a rag and wiped around the intake while holding the 'barn door' down.

This might be your problem. Your mileage may vary.

 

Yes, along those lines, but I'd make some other measurements before replacing the O2 sensor (if unplugging seemed to help) -- e.g., confirm the "ground" signal at the injection ECU is a truly good solid ground 0V (if this ground floats up even a few tenths of a volt, it messes up the whole system) and measure the output of the O2 sensor at warm idle (both plugged in and unplugged).