Engine Performance problem
1995 Toyota Tacoma 4 cyl Two Wheel Drive Manual 191000 miles
I pulled this code from my 1995 2WD 4 cyl standard:
P0170: The powertrain control module uses the oxigen sensor to calculate the AirFuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.
Probable cause: If bank one and two codes set together suspect fuel pressure or MAF sensor. Or oxigen sensor defective, or ignition misfire repair, or fuel injector problem.
The history on this vehicle is that I had the engine light turn on after driving several miles after an after-market air condition was put on. Ever since I will get the same O2 sensor fault code and had the catalytic converter change and 02 sensor and it would not do it until someone had the the catalytic converter changed for California make which the vehicle came from. The engine light did turn off but came back on and I just ignored it for the longest time. It finally turn off and then the last code I quoted above came about 3 weeks back. I used Lucas injector cleaner and pulled code the last code above which included the P0100 code for faulty MAF sensor. I think it could be the after market air conditioner. I pulled the MAF and it showed that it has resistance and I had it thoroughly cleaned. The codes were cleared and the P0100 continues to be displayed and nothing else.
I disconnected the MAF electrical connector and test the engine if it will change, it did not. So I had it replace on the spot at Autozone and as I soon as I turned on the ignition the engine started. I have driven it for 100 miles since and no longer runs rich or have problems starting.