General CEL on but no codes seem to be present

[sfhackney87]

In an effort to not waste anyone's time I checked the resources tab for most common FAQs and the 10 most discussed topics and couldn't find what I was looking for. So here I am with my first forum post:

I have a 1992 Plymouth Laser RS and it ran fine for the first two months I had it and now the CEL is on and there a huge loss of power and sputtering whenever I give it gas from a stand-still.

I have an old Snap-On ETHOS scan tool from my wrenching days a little over a decade ago. Lo and behold I also still had all my old the OBD-1 adapters. Of course the MITSU OBD-1 12-pin adapter worked so I plug it in and it won't communicate with the ECM. I also tried the old bypass trick with my test light to count the long/short flashes of light to jot down the codes and all I got was a solid light, no flashes.

Aside from replacing the vacuum hoses and shotgunning an airflow sensor on it... do you guys have any ideas of how to properly diagnose this issue?

Thanks a TON in advance!

 

[dwb]

It would be worth opening up the ECU and looking for leaky caps.

 

[steve]

If you're getting a solid 12v on the diag data pin (#1) the ECU is damaged, it's not running after it turns the MPI relay on to power up. Capacitors leaking is the the first suspect.

A good ECU would be putting out either a heartbeat or pulsing out the fault codes. I'm surprised the car starts at all, they usually don't when there isn't a heartbeat.