During driving the engine cut off and stoped suddenly when accelerating. It did not restart and was transported home. Next day it restarted again.
SYS was shown in the instrument, no other indications were shown.
I disconnected the battery and did load it fully.
I took the ECM out and cleaned all contacts and put it in again.
Then I replaced the fuel filter.
Next step was to connect a diagnosis instrument which I have from a 1988 C4: No trouble codes. Everything seemed ok again.
But after getting to normal temperature the problems came back again: the engine stops when accelerating about 2 times in idle.
But still no trouble codes.
Any ideas about what I shall try next are welcome!!
Thanks for your support.

 

When it’s dead, check for spark and then fuel pressure.
If those are good, check injector pulse.

 

Thank you, I will try tomorrow and see what the outcome is. I wonder that there is no trouble code which should give some direction to where to look further.

 

SYS indicates a Current trouble code in the CCM. The CCM controls body functions including processing the LCD data. The CCM is not the same as the ECM which controls the engine.

When you say "no codes" I suspect that you did not query the CCM, because if you had a SYS there should be a History code in the CCM. There are onboard diagnostics in the 1990-1996. They are informative for CCM and ECM codes for the 90-91.

Jumper A and G in the ALDL.
Turn the key to RUN and watch the speedometer LCD.
There is a 'little number' that is the Module. Module 1. is the CCM, Module 4. is the ECM.
Watch the codes go by and write them down. When "- - - " is displayed, that is the end of the data for that module.
When Module 4 "- - -" is displayed, the system goes to 1. and waits for further instructions.
A "C" code is Current. The fault is currently present. An "H" code is a History code, it has set in the past 50 ignition cycles. A "C" code is always accompanied by an "H" code.
If you get lost, or want to see them again, turn the key off for about 10 seconds and back to RUN. It starts over.

F - E - D - C - B - A
G - H - J - K - l - M

Disconnecting the battery does not clear CCM codes. If you had a SYS, there is a CCM History code. Use the onboard diagnostics and report back. Cheers.

 

Thanks for your input. I will follow these steps and come back.

 

I went through the list of IHBD:1.0 gives H41 and then three lines Aftre that thre is 4.0 with three lines.
When I attach my AuotXray there are no trouble codes at all!?
For H41 I found: "Loss of ECM serial data communications"which does not help me as I am an electronic nut.
The car starts everytime like normal and it behaves also as normal on my drive as long as it is not warm. Then it stalls when I try to accerate and it does not start again.
When I searched fora new ECM I got the impression that these are rare like hen's teeth.
Are the ECM's the same (identical) for US and European cars?

 

H41 is the smoking-gun indication of a known problem with the 1992&1993 ECM that affects drivability. For it to pop up in 1990 ECMs is rare, but I have seen a couple of reports on here of it occurring on a 90.

Clear the code. Jumper A&G, turn key to RUN, let the codes run until 1.0 is again displayed.
Push TRIP/ODO until "1.7" is displayed.
Push and HOLD ENG/MET until "- - - " is displayed. The codes in that module (1, CCM) are now cleared.
The next time it dies, check for codes again with the onboard system. If 1.H41 is set again, it is the engine ECM.

I realize you are in Sweden, but SIA Electronics are the go-to solution for the 92-93 ECM. You might contact them regarding the 90 ECM.

Your scanner thing can only access the engine ECM. The H41 is setting in the CCM which your scanner thing does not read. That 4.1 has only "- - - " means there are no codes in the ECM; your scanner is correct for the ECM.

Regarding "Are the ECM's the same (identical) for US and European cars?"
Is your car an originally built for export car, or was it exported/imported a period of time after it was built? There are RPO codes on the sticker under the console door for Export Equipment for various countries. If you can post a picture of your sticker (we call it the Service Parts Information Decal or SPID) there are peeps here that can tell you if one of the codes is an export code. The calibration (PROM or Calpack or "chip") may be different for a true export, but the ECM itself will be the same. You transfer your existing PROM/Calpack to the replacement ECM.

 

Wrap on the ecm while it’s running see if it dies. I have a few 1227727 ecms if you need for cheap.

 

Thabnks for your excellent guidance. I am a few days away but will follow the steps when I am back and report.

 

Thanks for your offer! I will come back when I should need it; but I still need some time.

 

OP said he's workng on a 90. Does the 1227727 come out of a '90? I don't know much about ECMs, which is why I ask. And I've been considering picking one up as a backup on eBay or some place like that. I've just not done so because to be perfectly honest, I just don't want to buy someone elses old busted/no good junk. And unfortunately that's what hapens a lot of the time when it comes to listings for parts like that on eBay or similar.

The one I have now came out of a Buick Regal. Was on the car when I bought it...

 

The 1227727 was used in lumina and 90-91 corvettes. The only difference is the calibration chip. I bought a few for the memcals and don’t have a use for the ecms .

 

Ok, back again and did what you said:
Engine display came only on after starting the engine!? With the ignition on it stayed black. After going through the steps you recommended there was a new trouble code showing up: C12
And the display has now fully given up: even no display of any information with the engine running!? it stays black but the engine starts as normal.
Do I need a new ECM or also the other control unit?