M40b16 engine cutting on aceleration

[blood69]

Hi everyone
I'm having an pain in the ass issue with a 316i m40b16 engine
If I apply any engine load on the car, it cuts power on what it looks like it's an ignition issue. The rev counter drops to zero and then goes back to normal.
I changed all the ignition system last year. Plugs, ht leads, dizzy rotor, dizzy cover and ignition coil.
Also last year I changed the CPS and the ECT sensors.
All new stuff.
This behavior of the rpms suddenly dropping on the tach below on what should be reading when the cut happens, gives way the CPS sensor, harness or ECU.
Last year I put a brand new CPS from Valeo and fixed another issue that I was having at the time.
Assuming that the E30 are known to Eat CPS sensors, I bought a new one from Vemo but when I tried on the car the issue remains.
I check both resistence from both CPS and they are at 560ohms. I also checked conected to the harness and pin 48 to 47 from the ecu plug and got the same results. So this eliminates the harness I guess.
I open the ecu looking for shorts, first test was pin 47 to pin 2 (ground) got resistence. But pin 48 to ground got 3.3ohms. I don't know if this is by design, I've tested all the caps and resistors from the ecu and didn't find any short.
The AFM I did a test driving the car and the voltage goes smooth, when the cut happens the AFM is still giving voltage, no suddent drops.
I also tested the one year old ignition coil and got primary of 2.5 ohms and secondary 8k Ohms.
The last thing that comes to my mind is the harmonic balancer, I clean it up and it doesn't seem very rusty.
What do you guys think? It's time for a Standalone Ecu or I am missing something here

[Speedtouch]

I would start with checking the basics, such as engine-to-body earth strap(s), and that you have a decent DME (ECU) relay.

Also verify that the ignition switch is giving a reliable supply to the engine electrics.

[blood69]

I would start with checking the basics, such as engine-to-body earth strap(s), and that you have a decent DME (ECU) relay.

Also verify that the ignition switch is giving a reliable supply to the engine electrics.

Thanks for your reply.
I had a friend with his e30 here at home and i swapped his ECU, DME and Fuel relays to my car. And the issue remained.
I also tried my relays on his car and they worked fine.

About the ground, I do get good ground measured with the multimeter both in the block and the head, about 1.8 ohms.

You mentioned the ignition switch, you mean here the key operates to start the car?

[Speedtouch]

Yes. If the ignition switch has worn contacts, you won't be getting a reliable power feed to the DME/ECU.

You could try bypassing it altogether, and running a direct +12V feed to the ECU, obviously ensuring you are feeding the power to the correct terminal(s).

You mentioned it only dies under load, so does it run reliably while just sat idling?