Classic Audi » Technical » Mech/Tech » Electrical problems » No Spark, No pulse from ECU. ABT/KV

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Old 31-10-23, 09:33 AM   #1
Tim_B4
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Lightbulb No Spark, No pulse from ECU. ABT/KV

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.
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Old 24-11-23, 01:13 PM   #2
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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!
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Old 24-11-23, 09:42 PM   #3
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Are You getting signal from from hall sensor?
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Old 25-11-23, 10:48 AM   #4
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I have a clear pulse coming through the signal wire on the hall sensor with the oscilloscope, yes.
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Old 25-11-23, 12:10 PM   #5
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I've also tried another motronic control unit/ ECU and it made not difference.
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Old 25-11-23, 09:03 PM   #6
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Could it be K-Jet wiring - ECU pins are different to EFI ECU?
Seems like a problem with wiring.
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Old 26-11-23, 11:28 AM   #7
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I didn't change the original loom out from the ABT 4 cyl that was originally in chassis.

The K-jet that WAS with the engine, wasn't KE-jet, it didn't have/need any connection with the car/ECU. The new EFI ECU is a standalone unit, the doesn't have any communication/overlap with the original ECU in the car.

The EFI ECU has coolant temp, hall sensor, lambda, idle switch and control valve and MAP sensor, so has no part/say in the ignition system.

The mono-motronic control unit is solely responsible for the ignition, and it's no longer giving a signal to the ignition coil, like I said, it has a clear signal from the hall sensor in to it, and all the 3 wires from the hall sensor have continuity with their respective pins in the ECU harness.

I have no idea why it's no longer giving the signal.
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Old 27-11-23, 12:40 AM   #8
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The 2-pin coolant sensor... One pin is for KE-Jetronic, the other pin is for the VEZ ignition module.

When you have the VEZ module you no longer have to time ignition with strobe light. Set everything according to marks (flywheel, cam and distributor) and that's it.

Rotor must be 10mm wide minimum or you will have a 4.500 rpm rev limiter ;-)
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Old 27-11-23, 04:17 PM   #9
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Thanks for your reply.

The original engine, whose loom I'm using, wasn't KE-jet, it was mono-motronic.

I'm not sure what a VEZ ignition module is, but my ignition module is https://www.supercheapauto.com.au/p/...SPO513894.html

Think the part number is IGC-192

I'm sorry but I'm not sure what you're suggesting I do.
Could you please give me some more info.

Thanks!
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Old 05-01-24, 01:41 PM   #10
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Still super stuck with this!

Any help would be unprecedentedly appreciated.
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