ECU / Unit Control / Injector Troubleshooting

[Cyrano]

you understand this is a switch? Operated by a cam in the distributor

Yes indeed! ;-)

We made 2 different tests to verify it is working properly:

• 1st test: we disconnected the connector from the distributor and make the engine turn using the starter. We used a small diode with low voltage connected to pin 12 and pins 21/22 and observed the diode blinking while the engine was turning (alternatively on 12-21 and 12-22, which shows that circuit is being closed alternatively by the distributor contact cam).
• 2nd test: similar to the above but with the full wiring up to the ECU connector. In that cas, we used a multimeter to observe open/close contact alternatively between pin 12-21 and 12-22.

That screw should have 1.5 threads showing at the bottom- no more and no less

I'll check how much there is.

 

[sfdon]

The E9 forum has a Parts library loan program

If you want, I can send you a package with a different manifold pressure sensor a TPS trigger points and a computer as a loan

I do ask for loan packages like this to come back in a timely basis for others to use

 

[Cyrano]

Hi sfdon,

Thanks a lot for the proposal. I'll keep that in mind.

So, I made a few trials yesterday. All the sensors were checked and confirmed to be in spec. Finally, verifying the harness, I noticed that there was some discontinuity on the wiring, specifically at the pressure and the throttle sensors. Bad connections were identified at the body connectors, and some pins were making spurious contacts. Tines looked a bit loose but after some cleaning the continuity in the whole harness came back. Engine restarted and ran during a few minutes, as expected.

The harness continuity was checked and confirmed ok before the 1st start-up, so I am assuming that heat and vibration on the 1st run created the discontinuity condition. I’ll make a deep cleaning and reconditioning of the contacts in the coming days.

Note for the future: always verify continuity of harness before going through crazy sensors/ECU investigations...

 

[TomHom]

We use this nice board to test the wiring and the sensors/ actors
.