I emailed about this before....my 92 740 turbo wagon is only getting
16 mpg after changing the O2 sensor. Thats' what the car was getting before I changed it. The M.A.F. sensor also died and was replaced recently, without improvement in gas mileage..I y'ed a new wire into the signal wire of the O2 sensor, and ran it into the pass. compt. With my el -cheapo digital DVM, when the car is initially started, it showed abt. 550 mv, and dropped as the car ran. It was not a stable voltage even initially. After a few minutes, it was fluxing wildly/seemingly randomly, between abt zero and 600 mv. When I get my FLuke 114 DMM, with analog bargraph, I'll be able to properly monitor the signal.
I also need to know if the water temp has to get up to a certain temp before the control system will go closed-loop. I am thinking they probably are all like that. So if the car is forced to run cooler than normal, can this prevent closed-loop operation? What is min. temp forclosed-loop this car?
The Haynes manual shows that there is also some manifold air temp sensor and a manifold air pressure sensor (besides the MAF sensor).... Where are these two devices located? I looked for these two sensors on Rockauto.com, they don't have them. I need to check/or replace *all* the other sensors.....gas is getting expensive! THe car still has no codes set...replacing the O2 sensor cleared the code that was set for that problem.
Thanks, Geronimo