ECU stroke

[MHarrop678]

Hello everybody,

I drive an Audi A6 1.8T, with the dreaded Multi-tronic gearbox (Yeah, its knackered but still drivable) and Engine code APU.

This morning I went to get into my car to go to work and It would start but would then cut out (Like 2/3 seconds from initial ignition). The engine warning light was on, however the computer and gauges wouldn't do anything.
I have removed the ECU and found that it has died (This is its second) because, when we tried to start it without the ECU connected, it did the same thing.
Does anybody know where I can source a new/used one? Or does anybody have any ideas why it would do this other than the ECU having died?

[Peter D]

Which ECU have your removed. If it was the Mototronic ECU then the car would not start at all. Regards Peter

[MHarrop678]

Its the one from the front of the car, just under the plastic cover near the windscreen.

[Peter D]

If you are talking about the unit with a large metal clip holding it in then it is the Motronic Engine management ECU and car will not run without it. You would have no injectors firing or any spark. You need to replace it get some help to read the diagnostic error codes. Regards Peter

[MHarrop678]

Hmm, thank you for your help!
Is there any reason the car would start but die if the ECU was ok?
You don't happen to know what happens in the startup sequence with the car do you? What signal the engine is expecting to keep going?

[Peter D]

You say the gauges were not working. If you mean the fuel and voltage gauges then that suggest the dash insert was a problem. The 1/2 seconds running with the ECU in place could be the Immobiliser kicking in. You need a code read. I assume you have checked all the fuses. Regards Peter

[MHarrop678]

There has been a development!
After putting the ECU back in, it seems that the dashboard now works and we are able to start it for longer periods (We drove/shuddered around the block) however it judders horribly and (at idle) the revs bounce around from its usual ~800 to the point of stall and then back up to 800. When the throttle is applied it will achieve say 2000 revolutions, but then drop and stall. The computer is also now telling us that the brakes need replacing (which may well be true...)
Running if for a longer period seems to have helped (Whether this is because the oil has warmed up, I'm unsure) Its almost as if it has been left for a long long period without running. However this cannot be true, because I drove around in it for more than an hour on Sunday and have left it for longer periods before...

[Peter D]

Find a Vag Independant or a forum member that has Vag com/VCDS and get the diagnostic messages to help you identify the propblem. Regards Peter

[MHarrop678]

I shall! Thank you very much for your help, it is greatly appreciated

[MHarrop678]

Just in case somebody stumbles upon this and has had the same problem I just want to say that we cleaned the injectors and the car now idles ok, however still (on initial start) can rev erratically when Drive is engaged. This soon sorts itself out though and the car seems ok.
One of the coil packs needs to be replaced, so that may well be the problem. When I have done this, I shall update this so there is a record of the result.