I was having a very rich 1986 ranger 2.9l. I pulled the codes and I was getting a lean hego code. I changed the 02 sensor and that fixed the carbon pouring out of my tailpipe problem. It still smells rich, but no carbon. I erased the 41 code (02 lean). the ranger is driveable now but idles up and down. I pulled the codes again. KOEO 89 code (Lock-up solenoid failure) KOER 41 (lean code ) . I don't understand why its giving a lean signal. I checked the wires and there not burned. Does anyone have idea's?

 

Have you checked the O2 sensor wires all the way up to the PCM? I would use a volt/ohm meter to check them to make sure the O2 signal is getting all the way to the computer.
Isn't it a 3 wire O2 sensor? Don't 3 wire o2 sensors ground through the exhaust pipe? I have heard of cases where such a lean siganl is the result of a bad ground connection, either for the sensor or the computer. In one case, after eliminating all other possibilities, I found I had a bad computer once.
That said, are you certain that the engine isn't really running lean? What's the fuel pressure look like? Any vacuum leaks? Any misfires? Any exhaust leaks?

 

Rough idle and code 41, vacuum leak

Its a vacuum leak
Joe

 

I cleared up the code 41 the plug was disconnected. I soaked the air idle vavle in dunk degreaser and also the egr valve. I ran a new vacum line to transmission and replace all vacum lines (Accept the one going from the fume canister to fuel tank. The cleared the codes. I drove it and the overdrive workes alot better now. But that nasty erratic idle is still there. I checked almost everything I could think of acept compression test and fuel pressure test ( I don't have those testers). so far no more codes I will check them after I drive it abit more. it almost like the computer is advancing and retarding the timing. Mostly occurs at red lights.

 

Do you have a digital volt meter?

 

yes I have a digital and anologe.

 

probe the TPS on the middle wire and make sure that the voltage is .9 or less.
If it is more than that, the computer thinks you are giving it the gas. The idle will be erratic because the computer is getting mixed signals.
Is your TPS the adjustable kind?
Joe

 

I Fix each code. NO more 89 code ( the plug was unplugged). I think the 41 code is still there in KOER mode. But my main problem was the irreactic idleing. I tested the air idle control , the resistance was good. I also cleaned it. I didn't think it was that until today. Just for kicks I took a AIC off a 2.3l and put it on my 2.9l. And now it runs like new.