My brothers 93 302 with a E4OD, just had the o2 sensor replaced due to some rough running and the scanner said that the o2 sensor was reading lean condition and was replaced. Ran fine for three days and now when it gets to operating temp it will barely idle above 500 and has little to no throttle response. This time it says the throttle positioning sensor is hay wire reading back and forth from 2 volts to 65 volts. We heard that cleaning the prongs in the sensor will cure it. Or could it be a bad cpu. What to do?

 

Did it occur to anyone that the sensors MIGHT be reading lean because the engine is RUNNING lean??? That's what the code actually says, if you read it. NO code means to just replace a part - they all tell you where to start your diagnosis.

Get a Haynes manual or a Ford service CD (do some Googling for the free download) & test the TPS. If it actually tests bad, then try cleaning the terminals or replace it. If it tests good, re-read what the code definition actually says & think about what it means. I find it helps to read a few versions of the definition because they're worded slightly differently, and it's like getting a different perspective. Read this thread & the code list linked in it. Another version can be found on this site & his old site.

Replacing the EEC is always the LAST option - they almost never go bad.