Hi, I am new to this site but it looks like there is a wealth of experience here. What a delema! I bought my Bronco 2 new in 1987 and have loved it. I have had my share of common Bronco 2 problems including tranny trouble but basically it had been a good truck until now. Rich, black smoke to the point it chokes itself out. This problem started gradually and is to the point that the vehicle will only run at idle or full throttle. The First thing I replaced was my throttle position sensor (TPS) but that wasn't it. I have now replaced every sensor and control device under the hood and the thing still runs extremely rich. And I mean replaced everthing!!! MAP and 02 sensors, Air temperture, water temperture sensors, TPS, fuel filter, EGR system,even cleaned all the carbon out of the egr passage ways in the upper intake manifold. Oh yeah, fuel pump pressure regulator can cause this problem but that checks out fine as well. I consider myself a pretty good mechanic and have ran everykind of diagnostic check I can other than a Ford break out box. Ford wants $100 just to hook up and other mechanics are leaning toward my ECU being bad. Ford doens't make ECU's for Bronco II's anymore (according to my dealer) and every junk yard in america seems to be out of Bronco II's to take one off to see if that is the problem. What have I missed? My wiring is in like new shape, in fact you can eat off about anywhere under the hood. The truck has been well taken care of. I am at the point where I am debating shooting it to put it out of it's 5 mpg black smoke running misery. What should I do? Any suggestions?

 

It seems like you have just about done everthing. Need to brain storm. Is it oil or gas smoke? Are the plugs oil fouled or gas fouled? Has your oil comsumpton changed any? I have seen in the past were leaking valve seals & low compression due to worn rings caused a lot of smoke in older high mileage cars. Also I have seen where a bad vacum modulator on an auto transmission was letting transmission fluid be sucked back to the engine and than burned. If gas fouled it could be bad fuel injectors. My 2 cents worth. Good luck and let us know? I have been scratching my head on a problem with my 89 Bronco II that I posted a couple of days ago.

 

Thanks for replying back. I wished it was that simple. The smoke is charcoal black and the truck has never used oil and the tranny was rebuild at 60,000 miles. It has 96,000 on it now and my tranny fluid is at the level I left it last year when I changed it. I am going to check with my ford dealership to see if there is a way to check the ECU on a machine and/or have it recalibrated. I have read where they are calibrated at the factory and the settings can change as they get old. It seems real odd to me that ford would quit making a "one of a kind" part that is vital to the truck's operating that is less than 20 years old. While ford may not be breaking any laws by doing this they may in-directly be violating federal law by not ensuring their products are complying with emission standards. How many other old fords may be running around blowing black smoke because the owner can't get it fixed through no fault of their own? I will let you know what I find out about my ECU, if for nothing else I will confirm it is bad. Ken