No Spark, No pulse from ECU. ABT/KV

Tim_B4 · 31-10-23, 09:33 AM

Hey all, wondering if anyone could shed some light on a problem I'm currently having.

I have a 1993 Audi 80 B4, that originally had a 2.0e ABT, that worked great.
It now has a 2.2 KV 5 pot swapped in, and I'm trying to get it running.
The 5 pot was K-jet, but as that caused me a world of trouble, and I couldn't get it to work right after several rebuilds, the engine is now running an Invent Jetronic EFI conversion.

However! I no longer have any spark coming from the coil, I've hooked a plug up to the king lead spot and I have no spark at all. I have 12V at the coil, and using an oscilloscope, have seen a cranking pulse from the hall sensor on the dizzy.

Here is where the problem is, I do not have any signal coming up to the coil/module.

I understand that there is some form of ECU in the passenger footwell, that the signal from the dizzy goes in to, presumably, the ECU then does something and then passes the signal to the module, then coil.

Is there anything that might be blocking this signal from getting out?
Am I missing a connection that the ECU needs in order to pass a spark signal?
It sparked just fine when I was diagnosing the K-jet, but now I put the EFI kit on I have nothing.

For the installation of the EFI, I have spliced a few wires, one in to the hall sensor and one in to the coolant temp sensor. I've redone the hall sensor splice and it's a good and proper connection, as this was my first thought.

One final point that could potentially matter, I'm running the power for the new lambda sensor, and throttle position sensor from the 12v terminal on the coil, as they're ignition powered.

Any help would be much appreciated.
Cheers!
Tim.

Tim_B4 · 24-11-23, 01:13 PM

I guess another way of wording this is.

Does anyone know what signals the ECU, on a 2.0e ABT, requires before sending a spark signal to the coil.

Cheers!

Sandro · 24-11-23, 09:42 PM

Are You getting signal from from hall sensor?

Tim_B4 · 25-11-23, 10:48 AM

I have a clear pulse coming through the signal wire on the hall sensor with the oscilloscope, yes.

Tim_B4 · 25-11-23, 12:10 PM

I've also tried another motronic control unit/ ECU and it made not difference.

Sandro · 25-11-23, 09:03 PM

Could it be K-Jet wiring - ECU pins are different to EFI ECU?
Seems like a problem with wiring.

24-11-23, 01:13 PM	#2
Tim_B4 Newbie! Join Date: Aug 2021 Location: South Wales Posts: 13	I guess another way of wording this is. Does anyone know what signals the ECU, on a 2.0e ABT, requires before sending a spark signal to the coil. Cheers!

24-11-23, 09:42 PM	#3
Sandro Grown up member Join Date: Feb 2011 Location: Chelmsford Posts: 651	Are You getting signal from from hall sensor?

25-11-23, 10:48 AM	#4
Tim_B4 Newbie! Join Date: Aug 2021 Location: South Wales Posts: 13	I have a clear pulse coming through the signal wire on the hall sensor with the oscilloscope, yes.

25-11-23, 12:10 PM	#5
Tim_B4 Newbie! Join Date: Aug 2021 Location: South Wales Posts: 13	I've also tried another motronic control unit/ ECU and it made not difference.

25-11-23, 09:03 PM	#6
Sandro Grown up member Join Date: Feb 2011 Location: Chelmsford Posts: 651	Could it be K-Jet wiring - ECU pins are different to EFI ECU? Seems like a problem with wiring.