Hey all, as you can see, first time poster, butI've been here several times over the years when I needed some guidance, andget good information. But this time, I can't find an answer.

1990 S-10 blazer 4.3l 2wd

What would cause the SES/MIL to act funky? Examples: sometimes it will come on during the initial key on diagnostics and stay on until started, other times it will go out before being started, other times it will not come on at all during the key on test, cold or warmed up.

I'm leaning towards the ECU/ECM. 1228062and APALprom, all AC Delco stock components

I'm having an issue, similar to a couple other posts, but its not always consistant, sometimes it will run fine (open or closed loop) then it will run bad, cuts out, won't idle correctly, dies(open or closed loop), but it is NOT throwing any codes.

Sometimes during these "episodes", the SES will come on and go out, other times it will blink so rapidly it does not allow the light to be bright.

And I've noticed sometimes that it seams to coincide with one of the relays on the firewall (fuel relay I think) while the engine is not running, just sitting in the seat with the key on wondering what is going on hearing the relay working then stop and watching the light.

Sometimes during the OBD1 jumper wire tests, it will only flash two of the 12 codes and not come on again, other times it works like it should, repeating the 12 code over and over the 3 times as it should if its not throwing codes, and I've had it not come on at all when connecting the jumper.

Not to take away from the main question (funky SES), but I've done most of the normal checks, fuses, fuel, spark, vacuum, O2, etc, I still want to pull out the EGR and clean it up, but I have done a hand vacuum pump check on it while the engine was running okand EGR is working.

All this still points me in the direction of the computer, but i really don't want to shell out a couple hundred bucks until I can get some type of test or confirmation.

Any thoughts or experiences would be great. Thanks in advance.
Mark

 

Bueller? Bueller? Bueller?

 

Guess this one needs to go into the stump the crew forum.

 

Actually, it falls into the check your wiring. The most common cause of intermittent problems is wiring/connector problems. Not fun for you, but nothing the rest of us can trouble shoot any further for you.

 

Fixed. Acutally not the wiring, thanks anyway. I guess Im the first person this has ever happened to. Lucky me.

 

Ok. Well, do you want to share with us what the actual problem was?

 

Well, since you asked, the computer.

I took a $30 chance from the local pick a part, and it worked, damn thing runs better than it ever has since ive had it. Computer tested well, I unhooked some things and it threw codes just likeit should.

Someday Id like to know if "limp" mode is different than open loop. Maybe some day I will post that question up to see if anyone knows.

 

Well, it's a little bit late now but I've been having the exact same problem.
It's not a relay clicking, btw, but the fuel injectors. I narrowed it down to either wiring or the computer, with a strong suspicion of the computer. When the problem is happening, the injectors click/buzz and the check engine light flashes erratically. This happens with the car not running but the key in the "on" position. I've wiggled all the wiring and visually inspected, but the wiring is all in order. I tried using a heat gun to heat up the computer's PCB, but I wasn't able to cause the problem to happen.

I'll take the plunge and try replacing the ECM since that fixed it for acton...