I was referred here from the TPI forum, they said you could help me.

I have an '88 TPI 305. When it started running poorly, I bought an AutoXRay. I've searched here and the web for the values I should be reading and found nothing. Could somebody direct me to a site that shows what I should be seeing? Mostly, I need to know how to figure the air/fuel ratio from the sensor values.

It was running rich, I was getting about 9 mpg. I think I've got it fixed. The ECM turned out to be bad. First I found corrosion at the connector and it still kept giving me wrong readings for the engine temp, about 50-60° high. A new sensor read correctly at first and then again started reading too high. I swapped out the ECM and now it reads correctly.

Also, I ran this for 6 1/2 years without the MAF and it ran great. Now, I have people telling me that it won't run that way. I now have the MAF connected but it doesn't run as well as it did without it.

 

Well that throws a whole different twist into your question.... You didnt mention anything about the MAF not being used. Without the MAF connected, you are forcing the ECM into "limp home mode" which while it will operate the vechicle...it wont do it efficiently, and you WILL run rich.

Connecting the MAF will give the ECM the airflow parameters it was looking for...however, if the maf is not a good one...that will cause even more problems. Did you use a new/rebuilt MAF or just whatever old one happened to be around?

You are proabably going to have to start from scratch as far as troubleshooting this one. I would disconnect the battery to clear any codes from your ECM. Make sure you have adjusted your Idle Air Control valve using the method in the tech articles, and along with that, your Throttle Position Sensor. Then run the car around for 30 minutes or so and see what codes pop up... and go from there.