Electrical New member needing help..codes 42,92, 12, cyl8

90sickfox said:

You need to check the o2 sensor harness. The 5 speed and auto harnesses are different but can be made to work for either by moving the jumper wire.

Electrical - O2 harness repin

This thread is a HOW-TO for the process of repining the o2 sensor harness to match ECU/Trans, in the event the car is swapped. See post 15 as to what the jumper should be repinned to. Step one. Remove the o2 sensor harness from vehicle. I find it easier to do on a bench plus it allowed me to...

stangnet.com

Now, those readings would indicate pegged rich. Check the FPR vacuum line. It shouldn't smell like fuel or be wet.

What color are your fuel injectors ? Didn't notice mention of the MAF. Is it the correct one for the injectors ? Bigger injectors than the MAF is calibrated for will cause this issue.

Is your manifold vacuum line hooked up to your MAP sensor ? 89 doesn't have a BAP.

( The next paragraph leaves out timing, load sensing, idle control, and several other systems that the computer uses to control the car. )

These cars are pretty simple. Maf reads air volume, computer reads it, uses reading to control injectors, computer reads o2 sensors to verify fueling conditions. Computer compensates fuel injection by the 02 sensors readings. The o2 sensors don't talk to the computer right away. Once engine is warm car goes into " open loop " and everything starts talking.

To test the o2 sensor you can take it out of the pipe, plug it back in, and run the car to operating temperature. The reading should be below .5v ( really more like .2v ).
The best way to test an o2 sensor is with an oscilloscope but ya gotta do what ya gotta do.

Click to expand...