PeachParts Mercedes-Benz Forum - View Single Post

crhenkel · #6 08-08-2007, 08:50 PM

Ok so I am in pure hell. I have a very nice 1986 W201 2.3-16 and I decided after all the reading I did about duty cycle and CO setting to check mine out. SHe smelled a bit rich so I thought, hey, I'll do it the right way and buy the meter and test it. WRONG!
I have read everything on the forum about setting the CO by duty cycle and by EHA. I added it to what I already have learned and already knew and put it all together and still have no explaination at to why I cant get the readings correct. I cant even get the 70% or 85% to read indicating a Federal or California car with ingition on and engine off. When I do this simple test at the X11 diag connector on the drivers fender well, I used both the 2-3 pin setup and the 3-2 pin test. Red and black leads in 2-3 and then in 3-2 and neither shows 70 or 85 percent. Red in 3 and black in 2 shows 50.6% plain as day al day. Red in 2 and black in 3 shows 49.8 all day long. Using a different ground instead of the 2 pin gives the same results no matter what. I have a spare ECU computer, correct part and numbers for the car, an exact duplicate and a working pull. I swapped it and is shows the exact same values for duty cycle. If some one wants to tell me I have two bad ECUs that went bad wit the exact same resistance, go ahead, but I think the ECU is good. Can anyone clear this up?

When I start the car , the readings all go way in to the 90's and fluctuate from the initail 50% after the warmup period is over. The o2 sensor is new and the eha is relatively new and does not seem to leak. Other than the car exhaust smelling a bit rich, the car runs great. maybe the idle is a bit low, instead of 900-950 as I think the manual states, it might be in the 750-850 range. But, no stalling, easy starts col and hot, no overheating, ac works fine, etc....just screwy readings that match nothing I can read or hear from anyone else.