Hello!
I have an '89 F-150 5.8L. I just replaced the engine, and it seems to be running great - although there is an intermittent roughness, not quite a miss on occasion. Here's what's got me scratching my head... Initially I would get a diagnostic code 41 - PCM didn't see the HEGO sensor. I found a ground I had missed during the installation, connected it. That cleared up the 41, but it was immediately replaced with a code 44 - Thermactor (smog pump) System not working. The pump is new, it blows air when the engine is running, and the diverter and bypass solenoids appear to be working. I had no fault codes prior to the engine swap - the old motor was just wore out. The vehicle does have unknown mileage - 200,000 would be my guess. The harness appears to be intact, some sensors were replaced, as were the fuel injectors and fuel regulator. I generally wouldn't know there was a problem if the computer wasn't tell me so.

Any help greatly appreciated.

Also, any tips on locating a set of manuals (preferrably on CD-ROM) that have the codes, and all of the test algorhythms? Haven't found anything useful locally. I purchased a service manual, took 3 large binders to hold it all, but it completely ignores things of this nature.

Thanks again
Larry

 

May want to try clearing the computer codes. My 89 F-150 w/302 clears by starting a diagnostic test on comp and pulling the connector out of the tester in the middle of the reading. May or may not work with yours.

 

If that doesn't work disconnect the battery for a couple of minutes reconnect it and go for a ride doing all types of driving. Then pull any codes and repost them.

John