82 380sl sluggish when warm- hot days

[Pennelec]

My 82 380sl is very sluggish after it is warmed up,shifts rough and running rich. Runs much better in cool night air. Motor does not miss, it just won't accelerate. I replaced 02 sensor and checked cats in exhaust. I am not sure 02 sensor is hooked up, as there is no change when I disconnect it and dash indicator does not work. MPG goes from 19 and 24 at best and down to 15 and 18. I have a spare Jetronic module and swapped it out. No change. When motor is cool and outdoor temp is cool and moist, it runs best and shifts smooth. Please help a new guy. Thanks

[ctaylor738]

I think that you probably have a rich mixture, so the car is OK when it's cold and warming up, but won't run well when hot. If your O2 sensor isn't hooked up, the computer may be seeing a lean condition and trying to enrich.

If you have a sensor installed, see what voltage you are getting between its wire and ground. Try to adjust the mixture at hot idle to .5 volts and see if that helps.

You can also try grounding the wire that runs to the temp sensor on the oil filter housing. That will put the system in open loop and should give you a constant 60% duty cycle. Then hook up to the sensor and adjust the mixture as above.

The right thing to do, though is to verify that the sensor is connected and adjust the mixture to a 50% duty cycle off Pin 3 in the socket. Lots of posts on this.

[Pennelec]

Thanks. I wiil check as you advise and let you know. Where can I find other post. Bare with me as I am new to this forum and MB.