Quote:Hi again thanks for all the help.(the ECU is dead with no power (cept, dtc memory) and can not send out codes, with the processor dead (key off, only one chip in the ECU has power and that is the memory chip, the Brain (processor) is 100% dead)
I talked with the mechanic at the dealership.
He said that the computer is sending out codes all the time even with the key off.
not only that, the CEL has no power to flash with key off.
I think he meant, is this, if the ECU sees errors running, you can key off and the errors are stored in memory if the Dome fuse is not missing or bad.
this would be a correct statement if not code 41. (bad spark is cleared , each key off, a fact)
The coil will burn up, if the Dizzy ignitor goes bad. that is a fact.
the ECU does not create or manage spark in 89/90 ,but it does monitor the Tachometer wire and will show code 41s driving or running if in fact spark messes up. but dont key off, or the code is ERASED pronto.
Quote:I also replaced the coil, the fuel pressure regulator, and the O2 sensor and it again runs, but according to the mechanic the computer is sending out codes all the time again any help would be appreciated
no that is wrong. its not sending codes out all the time.
but you can (per my ECU page) connect the Diagnostic jumper (be that a fuse or paper clip) and in fact drive all week with that plugged
in and if the ECU sees anything thing wrong , it will change from code 12s (good) to some other code. on the fly, running in any way .
Keep in mind the ECU may not report a Bad IGNITOR under some failure conditions. its not that smart yet back in 1990.
I belive it can only report, total death on the fly or 1 spark missing in 8 hits. and no other checks.
for example key on not started, it may not even notice the ingitor is ON, (bad)
his replacements are a good idea, on old cars.
btw2, my new guess, is you take car in to shop, for misfire.
and the mech, has no Tech1 scan tool so must shoot from hip. or an ignition analyzer scope.
so he does 60k tune up with 02.
and a new coil ( shot gun methods)
then it misfires again
2nd mech puts in 1 more coil, (not knowing there is a fancy igntor there) and you think the coil is bad 2nd time. no its not. he was just guessing.
we have bench tester for coils. so we dont need to guess. and can do the 2 check in the FSM to find bad coils (ohms)
My guess is it misfires.
this is caused by bad spark or fueling on a good engine.
This dizzy has VR sensor and needs the gap set right.
the Dizzy most not have a main shaft bearing bad, allowing that above gap to jog good and bad.
the Ingitors can fail in many a way and do love to fail this old.
The advancing weights can jam, and all power is lost. (they simply rust)
the Vacuum advance can fail too. in 3 ways, leak or be dead or even stick. (most are long dead now)
you never posted the reason for the 1,2,3, trips to the mechanic
what were all symptoms, each time.?
this is key to finding cause.
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