ECM questions

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Roadking_

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94 2.0L manual 166K.

If I remove the battery cables and wait 15 minutes the car starts immeadiately runs rough a minute during learning curve, then runs great and you can go drive it stopping and starting all day.

After sitting overnight it will not start. No DTC codes. repeats 12 when flashed.
I have removed the two connectors and cleaned with electrical spray and applied a bit of contact enhancer and no change.

So, I'm pretty sure its the ECM. I am willing to replace it at this point.
However; I would like to know the thoughts of those here as far as where to order one from and any experiences involved.

I was thinking the GM website because of OEM and they offer a $90 core.
I want to stay away from aftermarket bc of things I've read, but I cant remember where they said to definitely not order from.

Do I need to have it flashed with VIN or does the PROM retain that information?

Thank you
 
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Do you hear the fuel pump relay click and the fuel rail priming?( when in no start mode) Are you getting spark?

I used a EBay vendor for an S10 computor once, was happy with the service. I would in your case get a junkyard or cheap used computer off EBay to see if it is really the problem.

A lot of problems with GM wiring harnesses during these years of cars and trucks.

I had problems with my harness being loose at the firewall bulkhead connector.

Doug in P.R.:cool:
 
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Yes I hear it prime. I've replaced the pump because it wasn't producing enough pressure 38 psi. Now its 50psi.
When the ecm is reset the engine runs like a singer sewing machine. Can't release the ignition switch fast enough. But if it sits 8 hours with battery connected (new battery),
it wont start. Cranks and cranks. I know the thing is supposed to flash a code 51 if the ECM is bad but that's the only thing I'm not getting.

I was looking at the firewall harness but I didn't try to shake it. I will try to see if I can tighten the holding bolts.

I stopped driving this car because of the no start after sitting. It left me stranded at work. Started in the morning and after sitting all day would not start not even with a jump, and starting fluid.

I bought this car from ex mother in law who bought it new. It had 140k on it and she wanted newer car. She took good care of it and I drove it for two years before any trouble started. Then I let it sit for 4 years. I figured I'd have a few bugs to work out.
 
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perform a spark test and fuel pump pressure test when it wont run to narrow down the problem
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Check the cps wires and around the hole in the block( behind the a/c compressor) it goes into for leakage. Also the plug that goes into the coil its under the intake manifold.

The computer still used the removable prom and is OBD 1 in 94 ,, It has a part number and a 4 letter code... No dealer input is needed as it is on OBD2 computers.

Doug in P.R.:cool:
 
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Thanks doug in P.R.
I removed the ecm and the cover exposing the prom.
removed the prom to check pins all looks good. I set the prom back on the ecm the way it came off bc no directional installation indicator. looks like it can go either direction.
It has a sticker on the outer cover with service no. 16196393 bfrm.
when I google that number a whole bunch of places to buy a ecm for my year model and make pulled up.

My question remains: Where to buy a good one? GM parts online looks official and offers a $90 core charge money back.
 
Could also be the tps or coolant sensor also. I would suggest you find someone with an OBD 1 scanner to find the real reason behind the car only running in limp mode. (Sure beats changing parts.)

Doug in P.R.:cool:
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Good thing you put the prom in the same way it came out otherwise it would be toast.Seams to me the computer is loosing its memory while it sits. And it resets when its getting a jolt when its reconnected with battery voltage.

I'd try a cheap used one just to see if you get it to work before dishing out big bucks for a new one. ( unless new is reasonable $ )

Doug in P.R.:cool:
 
Factory GM parts are always better if they are still available. A lot of times you go to cash out and parts are no longer available though.:mad:

Doug in P.R.:cool:
 
92 Sunbird LE,
Thanks for the suggestion about the coolant sensor, but everything works when its running. There are no codes and the check engine light is not on, albiet I have not gone thru a drive cycle.

I went ahead and pulled the trigger with GM direct. after my core charge is credited back it will cost me $93.72.

I wish I knew who has a Tech1 scanner (OBDI). I have a cheap OBDII but it wont read the old codes.

I'll update this thread when I get the new one and let you guys/gals know if it worked.
if not there will be a 94 Sunbird LE w/manual trans for sale cheap!
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Hmm,
I posted in here late last night and its still not here. Something about a moderator had to approve message flashed for a second. I didn't think anything of it.

Anyway I went ahead and pulled the trigger and ordered a ecm from GM parts direct. After the $90 core credit it will cost me $92 for factory rebuilt and tested unit. I think that's reasonable. I will keep you guys/gals updated after I install it and drive the car and let it sit overnight. If this don't fix the problem there may be a Sunbird for sale cheap!
 
Well Ladies n Gents,
I got the new computer installed it, it ran just like before but the next day no start again just like before.

Soo, I'm back to square one.
Guess I'll be going back to basics, ie. fuel + Fire. Wrining wires out for the 4 major sensors.
Or install an RCCB and switch thru the ignition that cuts battery power every time you turn off the car and just drive the friggin thing?
 
Get a Hanes or Chilton manual, they have the test procedures , I used it when chasing my problem.

I 'm still thinking its the CPS ( crank position sensor ) they are known to get bad from the constant bath of oil they get and won't send a signal to the computer to send to the coil pack.

So when it hot, it won't work. If I remember right, you should get a reading when cranking on the pin on the computer harness.

If that works out, could be the module under the coil . ( all one piece with the coil )

Hanes is the one with the test procedures, Chilton has the better wiring diagrams.
You get them for next to nothing on EBay.

Thats all I can think to help you with.

Doug in P.R.:cool:
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now dang starter quit. Thought battery was dead. Hooked up start booster no crank. got meter out 13.8v. Starter engaged once sounded like dying battery. after that the solinoid engaged but no turn over.

We are getting aggrivated.
 
Mine came apart inside, which then shorted out the battery. Fun job to change it, one bolt goes in from the back and one goes in from the front. You will find leaning over the drivers side fender and holding the starter with one hand it the best way to start the install of it and by installing the transmission side bolt first. ( after all the wires to the starter are hooked up first of course from underneath the car) That bolt by the way is 18 mm.

Doug in P.R.:cool:
 
Yup Doug you are correct!
I pulled the starter off and the nose cone was busted clean off and end bearing gone!
Had to unstick broken piece out of the bellhousing.
The solenoid looked very old and rusty as well as the electrical connections. I used a magnet on a flexible shaft and tried to fish out the missing bearing but never found it. I removed the plastic cover exposing the lower flywheel and using mirror saw nothing either. Used a big screwdriver to slowly turn engine/clutch over a few times to see if it would fall out. Nada.
So installed rebuilt starter and so far the no start scenario has disappeared!!!

The car is sitting in driveway with a broken shift cable :-(
Ordered it, takes 5 business days to ship.

Installed new pulley for air conditioner and discovered the compressor or clutch is stuck.
Jumpered low press switch and killed the engine. Its not the orig compressor so I'm hoping I can unstick it.
 
on another note anyone know where to buy decent not too expensive seat covers for the front seats on this bird?
 
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