CEL stays on & No Code - Any input?

[clownmidget]

1987 22-RE with a lot of attention paid to it lately...fresh head, valves, pretty much new gaskets everywhere, injectors cleaned & balanced, later model 22-REC intake setup w/ plenum & TB, etc, etc.

Truck ran great after engine work until this past weekend when the CEL came on. Jumpered the TE1 & E1 terminals in the diagnostic port but got nothing. No blinking CEL, no change in engine timing, nada. CEL stayed on through several starts then finally was off at first start the following day.

With the CEL not on I jumpered the pins under these conditions and this time there was no CEL blinking, etc., nothing BUT the engine timing did change just as I'd expect for setting it.

So now I'm confused. It seems like it is not really throwing a code but perhaps it's the TPS or maybe something else I'm just not thinking of. I did test the TPS while the CEL was on continuously and it did test bad and I've got one on the way but the behavior of it now with the CEL off and still not getting the flashing/blinking CEL is making me think I've got some other issue. Thanks in advance

 

[WristPin]

there is a procedure outlined in the FSm to diag the check engine circuit. look for the link to the FSM in the FAQ.


this happened to my buddy's 87. i swapped him ECU's out of my 86, and it worked fine. that was the only problem.

 

[clownmidget]

Thanks, I'll check it out - I was thinking it was something that was only really affecting the CEL circuit.

So you were able to put the ECU that was giving the CEL in your truck as a test and it worked fine in every other respect?

 

[WristPin]

yep. only the CEL circuit was affected