Intermittent power loss Audi A3 8L 1.8T 1998 AGU engine

My Audi has an intermittent power loss and misfire. It can happen two days running, or be 2 weeks between problems.
There is no pattern to the power loss and misfire, and occurs no matter what the speed, load or engine revs.
There are no fault codes.
I have had 2 garages look at the problem with no result.
I have changed: -
ingnition amplifier
all coil packs
N75 valve
spark plugs
petrol filter
cleaned the throttle body.
One of the garages carried out a smoke test to check for leaky pipes.

Fuel consumption appears to be fine.

When this power loss occurs the car will idle - but roughly. If it is turned off and then restarted it is fine - no more misfire/powerloss.

This is otherwise a lovely car and I do not want to get rid of it, but I can't trust it.

Do you have a performance “cone filter” intake installed?

Quote:

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Originally Posted by Crasher

Do you have a performance “cone filter” intake installed?

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Thank you for your prompt response.

No, I do not. I believe the car to be in original spec.

What is being used to check for fault codes?

The vehicle was first checked out at an Audi main dealer. Following that it was taken to an independent garage that had a good reputation for working with Audis. Finally it was taken to an independent BMW specialist because I was impressed with their setup, the way they worked and that they had worked well on my BMW.

All found that the fault was not generating any codes.

OK, you need to start with a fault code read carried out using a VAG specific system such as VCDS.

Thank you.

I'll look for someone in my area that can offer this service.

Is there a VAG Com section on the forum that may list specialist offering this service in my area?

VCDS - Users Locations