So yesterday I decide to clean the throttle body and adjust the linkage on the throttle beacuse off idle response has been terrible and the throttle plate wasn't vertical when the pedal was all the way down.

I also had to adjust the throttle position switch so that it would "click" as soon as the throttle was lifted off idle.

When I put everything back together the car will idle roughly at around 900rpm with the O2 sensor disconnected, but when connected the idle climbs to about 2500rpm.

I thought it was an air or vacuum leak at first, so I double checked everything and that wasn't the case, even the inside guage shows a strong vacuum.

The idle adjustment screw is backed off so that the throttle plate is totally closed on idle, so there must be a reason the idle motor is letting through so much air.

I would appreciate any ideas or suggestions on where to go from here, I'm up at school so I have limited access to tools and books.

Thanks,
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Zack Silver 83' 242Ti (225k)

Hi,
I have this problem, and the solution was a fix a short on the wire harnes near to the firewall. Follow the fat green cable from the OS sensor, and you will see the the harness. If the OS sensor is faulty you will see black smoke but not high rpm.

Hope this help,

Edwin

Sounds like you need a new one.