More Mixture/Lambda woes
 

The car is my dreaded '92 300E. The car has about 160K. About 15K ago I replaced the catalytic converter and various other items after it started running rich. I THOUGHT the problem had been fixed but it seems to have come back with a vengance.

When I check the duty cycle...it's stuck at 81.35. The car smells like it is running REALLY rich and will often die as I try to pull out of intersections. It is getting to the point of being dangerous. If I spray FI cleaner in the intake, it runs better for about 10 min and starts the mess all over again. I'm at my wits end on this. At this point I don't know WHERE to start testing or what to replace. I've spent on this car until I've had it. I'm getting around 14MPG and it's eating me up on the daily commute...plus having to put the car in neutral at stop lights. It's IMPOSSIBLE to drive in the city with the A/C on. :eek: This is Texas. It's HOT.

I'm open for any suggestions. I keep parking it under trees HOPING that a limb will fall on it...but none such luck.

My guess is that your duty cycle meter has a little drift and you should be investigating an error code 80.

Sixto
95 S420
87 300SDL

Sensor
 

It could be the oxygen sensor.

Your vehicle should have the stored codes in the computer, not only the duty cycle. If the vehicle is a 1992, it should have more diagnostics and codes.
80% duty cycle means a bad intake air temperature sensor or the altitude sensor (they could be one of your problems). But an O2 sensor sounds more like it.
By the way, how is your wiring harness??

I've never even looked at the wiring harness as it wasn't normally a problem with the '92 model year. The O2 sensor isn't that old...but who knows. Is there a particular test for the air temp sensor or alt sensor? I'm trying to save as MUCH $$ as possible right now and am trying to avoid a major trip to the shop.
I guess a trip to the shop is cheaper than the gas I have to keep pouring through it. :(

There is a test for the air temp sensor. It is buried somewhere in the manual CD.
I could e-mail you the whole section in the manual, and you would have to search it. The file is about 5 megs (.pdf - 173 pages). Send me a PM with your e-mail. I am too lazy to look for it.