Mondial T: intermittent left/bank tacho shut down..

Hello

I have a problem that appears last year when I firstly drove the car in may after the lockdown..: after a few miles (10/15), I am loosing one bench of cylinder and the tacho is oscillating between 0 and 1000rpm.
Quite confident I ordered 2 crank sensors and in the mean time removed the transmission for a main seal change.
I had a hard time starting her again on 8 cylinders this summer, losing the left and/or right bank that I managed to solve while jiggling around with the cranks sensor but this was the last time the right bank was causing me problems.
Since them I have tried a lot of things, but the problem is still there: I am losing the left bank and the tacho (the left bank is the one sending the engine speed to the tacho).
-usually it will happen after 10/15 miles and if I stop the car a few moments (1h), it can be fine and I can drive it hard for 40/50 miles without issue
-sometimes I don't have problem at all during a ride or sometimes it won't restart for a few hours or when I am unplugging things (but never the same!)

I have replaced both coil packs and swapped the ECU, the ignition power modules, the 3*2 relays in the trunk and checked the fuses in the trunck...

Obviously the question is either if the ECU is losing the crank signal or if it is turning off for some reasons. I was thinking about the left crank sensor angle part that is going behind the cam cover since I remember during my last major to have started to bolt the timing cover on a cable.. but I tried today during the problem to jiggle the cable just before it is going behind the rear cover with the engine run and it was not doing anything so I am not sure. Today it restarted fine after unconnecting/reconnecting the barrel connector, but once it was with the ignition power module, but since it is working again by itself it is hard to understand something.
I realized today that during the problem, the left fuel pump and ECU relays are clicking.
I had the feeling today that my left fuel pump was making maybe more noise that the right one since I was hearing it from the inside when idling.

So to be honest I am quite lost today without real clue...!!

If anyone has an idea I would take it!

Thanks

 

Hello

Well I have spent some time on this issue and can't solve it..

I have checked the crank sensor cable and it is fine.
I noticed that the wiring harness was worn at the sensor plug so I repaired it with a new JPT connector... but I then realized that it was only the shielding that was worn at the plug so not a big deal.

The TDC sensor resistance at the ECU connector is the same for both side.

I have then noticed that if I unplug the ignition on the left bank, then the rev counter is working.. obviously the left bank is not firing but looks like the problem is gone.

I have then also replaced the two ignition power module (coils are new), swapped between the banks the plugs and the HT leads..

The problem is still randomly here (left bank shut down, rev counter on the dashboard dead, left bank relays clicking).

However, if I unplug the left coil pack plug, the rev counter is working back and the relays are not clicking.. I tried to unplug the fuel pump but it does not make the same effect.

I start to really become clueless with this problem..

Does anyone has any idea that could help me?

Thank you