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.