Well, the rumors of my car's fix were greatly exaggerated. It is still running off maps, while generating no relevant error codes. It is also running very rich, and my plugs are getting nastier by the minute.

The way I see it, there are three possible reasons for the car to not enter feedback (i.e. closed-loop) mode at cruise: (1) THe ECU is bad. (2) The ECU is getting info that sensors are broken, and is so operating in a safe mode, and (3) The ECU is getting incorrect sensory input that it is interpreting to mean that it shouldn't be in feedback mode.

(1) Swapped a different ECU, no change.
(2) There are no relevant error codes being generated. I get a knock sensor code on the one ECU which I know is ECU related, and which has been there for a while with no ill effects. At any rate, its not present with the other one. I also get an occasional speedometer sensor error code, but again...that is not new, and shouldn't have anything to do with it anyway.
(3) Thought maybe bad temp sensor making the car think it was in warm-up mode all the time. Replaced it, but no change.

It seems to me that the answer is (3) but I am running out of possibilities there too. Any suggestions or ideas, send 'em along!

jds

 

Here's a question that's probably a stupid one, but...is there any reason at all that badly fouled plugs could somehow result in the car not entering closed-loop feedback mode during cruise? It doesn't seem likely, but it is a problem that I know I have (hope to remedy this weekend) and I'm at a loss for what else could cause it that I haven't already tried.

jds

 

OK, I have the answer to that question...no, the plugs did not cause the problem...but they were sure fouled! Other than the problem mentioned in this thread (that I keep replying to myself on...c'mon someone give me some opinions here, its boring talking to myself) the car runs much better.

jds