I've been reading recently that it is detrimental to the ECM to start the car and run it with A and B terminals jumped on the diagnostics connector. Before knowing this, I had the two terminals jumped, started the car, drove around with it like that and eventually took it out. The check engine light was on before for reasons which I am still trying to figure out, but how would I know if I did damage to the ECM. The car still has pleanty of power when and where it should.
I think the ECM is bad to begin with, I have been having trouble with my EST control module and have had to drive around with the EST bypass unplugged. which brings me to another question:
In a 91 formula where the EST is built into the ECM, what on the ecm needs to be replaced so that I would have a new EST and are the parts still available?
Thanks

 

Any ideas on what damage would be done to the ECM if any? I found out that I'll neet to buy a new Memcal for the spark timing control module, but I don't want to have to buy a new ECM after the Memcal. The car still runs fine, everything works, except for the aformentioned.

 

jumping and running the vehicle is not bad. doing this tells you if the engine is running in open or closed loop. open loop is spark timing and fuel mixture set to what the sensors see at startup (less efficient) closed loop is the ecm is adjusting fuel and spark in relation to the signals from all the sensors.

You didn't hurt anything running it with a and b jumped

 

Oh well that's good news for me. Thanks for the reply

 

Not a problem at all.

In fact one of the test procedures to determine if the engine is going into closed loop involves running the engine with the A&B terminals jumpered and watching the SES flashes.

Jake

 

NO DONT DO IT... YOUR ECM WILL EXPLODE INTO A BLACK HOLE!!!


Nah you will be fine like everyone said before, its a diagnostic way to test for open or closed loop.

 

Thanks for the reply. You had me scared for a second.