ECU / Unit Control / Injector Troubleshooting

[Cyrano]

Hello everyone,

I am currently working on my engine and I am facing some issues with the triggering pins. I may have missed something, but I could not find any information on the forum…

Basically, when I switch-on the system:

• pin 21 is at 7V approximately and I can feel that injectors 2, 4 and 6 open.
• pin 22 is at 0V and at no time the injectors 1, 3 and 5 do not open.
• when I crank the starter, pin 21 voltage decreases slightly to 6V and pin 22 remains at 0V.

I checked all the wirings and the harness. Everything looks ok (good continuity all along the wiring for all the pins). Fuel pump is powered and auxiliary injector opens when the system is switched-on (before starting).

When testing the pin 12, I have a resistance of 7 Ohms against ground. I understood that it should be direct to ground. Not sure if it is related or not. Pins 21 and 22 are showing an infinite resistance against ground (which makes sense).


Based on my understanding of how the D-Jetronic works, I have the feeling that I am facing an issue with my ECU. Can anyone confirm? Should I check something else on my system before sending the ECU for repair or opening it?

Thanks for the help!

Have a great day!


Side note: there are a lot of information on the forum on ECU/Injection, and it is not always easy to find (research by “ECU” or “control unit” provides a significant amount of results). Most of the case study, troubleshooting guides or conceptual data I could find are related to the surrounding equipment, but not to the ECU itself.
It may be good to have all the ECU/injection related topics listed into one single thread. What do you think?
Here below are some links I found helpful (not already listed in the forum published source):
SW-EM Bosch D-Jet Notes
fuel_injection_fault_tracing.pdf

 

[sfdon]

Measure pin 12..... for voltage.

Have you inspected your trigger points? Not your points- your trigger points. The ones hidden inside your distributor on the side.

Have you looked at the schematic?

Very simple but expensive item that when it wears out you will get no signal at either pin 21 or pin 22 or possibly both.
This is the device that tells the computer to fire the injectors based on RPM.

Sounds like trigger points are worn out or distributor is worn.

There is a tool for measuring wear..

 

[bill]

Hello everyone,

I am currently working on my engine and I am facing some issues with the triggering pins. I may have missed something, but I could not find any information on the forum…

Basically, when I switch-on the system:

• pin 21 is at 7V approximately and I can feel that injectors 2, 4 and 6 open.
• pin 22 is at 0V and at no time the injectors 1, 3 and 5 do not open.
• when I crank the starter, pin 21 voltage decreases slightly to 6V and pin 22 remains at 0V.

I checked all the wirings and the harness. Everything looks ok (good continuity all along the wiring for all the pins). Fuel pump is powered and auxiliary injector opens when the system is switched-on (before starting).

When testing the pin 12, I have a resistance of 7 Ohms against ground. I understood that it should be direct to ground. Not sure if it is related or not. Pins 21 and 22 are showing an infinite resistance against ground (which makes sense).


Based on my understanding of how the D-Jetronic works, I have the feeling that I am facing an issue with my ECU. Can anyone confirm? Should I check something else on my system before sending the ECU for repair or opening it?

Thanks for the help!

Have a great day!


Side note: there are a lot of information on the forum on ECU/Injection, and it is not always easy to find (research by “ECU” or “control unit” provides a significant amount of results). Most of the case study, troubleshooting guides or conceptual data I could find are related to the surrounding equipment, but not to the ECU itself.
It may be good to have all the ECU/injection related topics listed into one single thread. What do you think?
Here below are some links I found helpful (not already listed in the forum published source):
SW-EM Bosch D-Jet Notes
fuel_injection_fault_tracing.pdf

If your trigger points are shot, you will need to get in touch with SFDon. Hopefully he has a replacement. Pay attention to him, grasshopper, for all things related to D-Jet. Get friendly with him, he will eventually save your ass.

 

[Cyrano]

Hi Don,

Thanks for your reply. I use a 123 distributor and the pin 12 is not connected.

My understanding is that pins 21 and 22 should have the same voltage inputs from the ECU. Then the distributor alternatively ground one pin or the other. Is it correct ? In original distributor, the ground goes through pin 12.
In 123 distributor, I guess it is grounded directly to the distributor itself.

 

[Cyrano]

Hi guys,

So, I finally made a trial. All the connections worked correctly, and the 21/22 pins was just the open item,. The good news is that the engine started. The bad news is that the engine did not maintain the idle and stopped after a couple of seconds.

After a few trials to work around the engine itself (incorrect grounding, auxiliary valve, etc.) I noticed that exhaust pipes of cylinders 2, 4 and 6 were "cold". That lead me to believe that the triggering of the injector was not working properly.
Working around the ignition (123) did not provide any better results, so I disconnected the trigger point connector to the white/yellow wires of the 123 distributor and mated it to the original distributor (not installed to the engine).
While I started the engine, my father rotated the distributor by hand, and the engine ran much better (not perfect but could maintain during a few second until we switched off the power).

I am suspecting something is wrong on the 123 distributor or the wiring. Anybody has already faced such issue with the 123 distributor (incorrect triggering)? If so, how can I sort this out?

By the way, I'll look for a distributor rotor (12 11 1 355 866) as this is the only missing piece of my original ignition. If anybody has a spare...


Below is a picture of the engine and its bench.

Happy Sunday!

 

[sfdon]

confused-

"and mated it to the original distributor (not installed to the engine)."

"I'll look for a distributor (12 11 1 355 866) as this is the only missing piece "

you have it or not an original distributor?

 

[Cyrano]

Hi Don,

Sorry for the confusion.

Indeed, I do have the original distributor but not the distributor rotor. I cannot use the original distributor/ignition system because I am missing this piece and all the prices I found on the European website were crazy high...
During my last trip to the US, I bought one rotor at Rockauto , which was supposedly compatible, but the part was too short and not touching the contacts of the ignition cap (~2mm too short). So now, I am a bit suspicious to buy a new one...

I have edited my previous message.

Below is what I am calling the distributor rotor. May not be the right word...

 

[TomHom]

Hi Cyrano,
W&N is asking 190€ for one. Each part getting rare becomes extremely expensive.

I may offer you a used, tested one for 40€ plus shipping. Where is your location now?
Thomas