I’m new on here . Anyway I have an 82 Z28 CFI with 29000 original miles everything is original except the tires and ECM. I bought a new ECM because I had a very high idle advised by a mechanic. Still have the high idle and now a solid engine light that won’t give me any codes.

 

Sounds like the ECM is dead. If the older CFI ECMs are like the slightly newer ECMs (TPI & TBI), it should blink the SES/CEL light at key-on, engine-off. This is a decent test to see if the ECM is actually running from the firmware and not in limp mode. Test is as follows:

While observing the SES/CEL light do a key-on, engine-off. The SES/CEL light should briefly turn on, blink off, then turn on solid. Can repeat the test after at least 10 seconds of key-off. The blink-off is the key, with that the ECM is running from the firmware.

RBob.