[s-cars] Diagnosing misfire cause

[Marc Swanson]

wouldn't it be nice if it was that simple.


The ignition module on the S4 is NLA and there is no currently known
direct swap replacement part.

your only hope at the moment is to swap a known good driver from a donor
ecu.


> They are an electronics repair firm. Diodes, resistors, and transistors that make up every ECU ever made are a universal truth. It's not like one is powered by unicorns and another has elves inside. In this case it's even more specific that it's a Bosch Motronic which is even more specifically what they are experts at. There are dozens of similar companies across the country offering the same services.
>
> I have never sent them an Motronic from an Audi, all were from Porsche's. 1980's 911's mount the Motronic to the floor under the drivers seat and they commonly get wet especially with leaky Targa and Cabriolets.
>
>
> In this particular case the most likely failure in the Motronic is the ignition output transistor itself. Anybody with soldering skills could open the case, read the part number off of the transistor, order or online, and replace it. There will only be a handful of medium current transistors on the board and they will be very downstream in the circuit so easy to identify the correct one based on continuity with the correct pin on the main wiring harness connector.
>
> -Cody Forbes (mobile)


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Marc Swanson
EFI Express

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