Invent Jetronic ignition control for VW/Audi

JHM

When you say check voltage with the ecu disconnected, do you mean unplug the invent ecu and check the emul pin on the connector with ignition turned to on?

correct

KielMiller

JHM 0 volts

JHM

This ignition amplifier requires too much current to turn on. So it's not compatible

KielMiller

JHM which amplifier is recommended?

Last question,,, i dont understand why I you were asking for voltage on the control wire? I wouldn’t expect to see any voltage on that wire as the ecu is what sends voltage down that wire to tell the ignitor to trigger the coil.

Thank you

JHM

KielMiller
It could be an inverted input, controlled by switching to the ground.

VAG 357905115

KielMiller

I picked up a new coil and have it wired in and have spark!

Now the engine will hesitate and not completely start so I put a timing light on and had someone crank the engine. With the timing light I was unable to get a consistent light and never could verify timing during cranking because it was inconsistent and when it did flash the timing mark was nowhere near the window. I tried adjusting the static preset to plus and minus 30 degrees as well as adjusting the cap on the distributor full advance and full retard.

I then pulled the plugs and laid them out and took this video of it cranking

https://youtube.com/shorts/dW7PaI6Hmkg?si=Ewh2sotOiApysa8J

Any advice is welcome!!

JHM

please record a log of cranking

KielMiller

JHM

analyzer-rabbit-20260317-083050.csv

865kB

JHM

The signal looks good.
Probably you need to invert the hall signal to get the spark into TDC:

KielMiller

JHM
Update,

I switched to custom and inverted the hall setting. This worked and I was able to verify the timing as being close enough to start.

Before putting the plugs back in I had to take a break and when I came back out I decided to verify again and I have now lost spark with hall sensor inverted. For testing I disabled hall inversion and spark comes back and as before its nowhere near close to TDC even with distributor turned full max either way or offset set to max -30/30. If I turn hall inversion on now I have zero spark or 1 random plug will fire but that is it.
Attached is a log file with inverted pickup enabled.

I have tried to reinstall the software with no change in behavior.

I have verified adequate voltage at 13v to the ecu and to the coil.

analyzer-rabbit-20260317-220449.csv

412kB

KielMiller

JHM we have already done this above

JHM

In the log, the spark is firing nicely.
What is the hardware version of the ECU: 2.4 or 2.5?

KielMiller

Ok,

I believe I have made some progress, Inverted Hall was not effective. I was able to adjust the distributor so it was reading 15 degrees BTDC during cranking..... The software does not show cranking ignition angle so I am not sure if this is correct. I am able to crank and get the engine to stumble while modulating the fuel throttle. Please see attached logs and video and advise.

https://youtu.be/UGcYK7QpazM?si=jlUKb46fkal0SEAX

analyzer-rabbit-20260320-183142.csv

1MB

JHM

According to the latest analyzer log, the inversion settings are correct.

In order to start the engine, you need to adjust the distributor with the strobe.
The spark should fire at TDC or slightly afterward (to mitigate pinging at hot start).

KielMiller

JHM ive verified that with inversion turned off that timing retards when out of cranking window. However,,,,,, with hall inversion turned on I completely lose spark. Im working on getting a fluke scope so I can verify correct output from the ecu to the coil when this is happening. What is strange is if I let it sit overnight, spark comes back.

JHM

KielMiller
Upgrade to the v4.1.6

KielMiller

JHM

Ok,

Upgraded to version 4.1.6.
There is now consistent spark with Hall Inverted selected, however it significantly changed the timing of TDC which was set in version 4.1.5…..With the distributor completely maxxed at advanced im still 15-20 degrees atdc.

JHM

KielMiller
Then you need to toggle the Hall inversion checkbox.

KielMiller

JHM
It is.
Just moving software changed TDC.

In version 1.5, with very weak and inconsistent spark with Hall Inverted, I was able to set it to TDC…… after upgrading to 1.6 the spark is consistent,,,, however its severely retarded and its so far out im unable to get it back to TDC.

The software update changed my TDC spark setup.

JHM

I confirm that v4.1.6 has issues with the Hall inversion algorithm.
Luckily, we have scheduled a car with an M102 engine for next week. We will resolve the issue, perform thorough testing, and create a manual with the recommended settings.

KielMiller

JHM ok,

If you need me to test anything please let me know…. Also while testing please check spark output. For some reason the spark output does appear weaker with hall inversion

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