My 86 240 has failed the e-test by running to rich. Seems like I read something on BB one time about un-hooking one wire (to ecu??) and it was kinda a quick fix for cars running rich. Would like more detail on this if possible. I have checked fuel pressure and it is good.
Thanks for your comments/thoughts.

don't forget to check ignition timing...i know in the modern world that this is nearly never an issue...but hell the car is 20 years old now...i reset my 86 244's timing from 9 degrees btdc to factory spec of 12 and it cleared up a few issues...idles smoother (still not great) and picked up about 3 miles per gallon everywhere.

The quick fix was to plug the vacuum line at the ignition control unit (ICU), but that is for high NOx, not high HC.

Post your test numbers and you will get help. Common causes of rich running are bad engine coolant temp sensor, dead O2 sensor, bad fuel pressure regulator, but we'll know more when we see your numbers.

Good luck!
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Herb Goltz, Aurora, Ontario, Canada '92 245 w/130K mi, '92 945T w/200K mi