D-jet miss in '73 Volvo B20

Hi Volker,

I have established that there is no break or interruption in the wiring harness between the TS and ECU by disconnecting from both and checking continuity.

It's possible that there is less power when accelerating with the TS or lead #9 disconnected, but it is not all that noticeable. These cars did not have that much torque in the first place!

I am at the end of the fault possibility line. I have now connected and spare, known good ECU and wiring harness to the system and will drive the car this morning. If the miss persists, I am out of things to check or do. Perhaps the owner will want a set of DCOE 45 side drafts.

New addition:  known good ECU and wiring harness makes no difference -- miss persists.

Well, it looks like I have stumped everyone in the worldwide community. I've done every known test (and then some) plus substituted a known good wiring harness and ECU without solving the problem.

On B20E vacuum advance correction is negative. Do you have a vacuum correction on your 123 distributor ? Are you sure C curve is the right one for a B20E ?

 

There is a vacuum connection on the 123, and it's plugged into the induction manifold port where the original Bosch distributor was connected.

I know the system uses vacuum retard, not advance.

Yes, Curve C is the correct one for the B20F (not E).

Hi to All,
I just got knowledge of an OPEL Technical Information from 1974 - maybe regarding the problem.

There are two ground connectors at the D-Jet-engine-harness that have to be connected to the two different screws  of the cold-start-valve.

Once removed the harness or the connectors, they both could be connected to one point.
This could lead to interruptions in normal cruising when the engine is warm.

Sounds quite strange, but Opel would not have published such an information without a reason. We know about other information regarding electrical induction... 

- I would try to connect the ground wires of the injectors to an additive, different ground... -

Regards
Norbert

 

Hi Norbert,

that souns gobbledygook to me. Why shoudl it make a difference if you connect 2 grounding points to both sides of CSV or just one. Contrary: It is always difficult if 2 ground connections are on differen potential. That can create stray currents and bad effects. But a difference between hosuing of CSV left side and right side on purpose is very strange.