problem at start

[peterpan]

Hi guys,
has anybody any idea or experience with this:
Sometimes the engine doesn't want to start. After some attempts it does his work, and does it well in the next two-three days. Then does it again.
Welcome any idea. Thanks, P.P.

[ZeroK66]

Hi Peter,

Some one on the B5 forum has had the same thing recently. DIdnt see a solution. Could be expansion in the fuel tank. Can try undo the lid on the tank to release the pressure.

Another thing would be to check your tempreture sensor. The car has one in the waterline to tell if the engine is warm or cold & then fuels the car accordingly.

Do you have the problem always hot or always cold? if it is consistently at the same temp then it is likely to be the sensor.

[peterpan]

Dear ZeroK66!

Thanks a lot your quick answer, i'm going to check these two possibilities.

Peter

[gregory]

Hi,

I have the same problem and I am trying to find a solution.

"Could be expansion in the fuel tank. Can try undo the lid on the tank to release the pressure."

What do you mean with expansion in fuel tank? Could you please explain to me?

Do you mean the "green" temp sensor, or does the car have more than one temp sensors?

Thanks,

Gregory

[ZeroK66]

I am not sure where the temp sensor is. Someone on here should be able to answer that.

By expansion in the fuel tank I mean fuel in the tank evaporating and this then pressurises the tank. I know this can affect some cars, not sure if it does the S4... but certainly worth a try.

[K2]

Having a very similar issue on my RS4, only when the engine is cold, and about once every two weeks....very random! However, the car is due to have a cam chain tensioner replacement as on cold start one of the chains rattles which can effect the timing of the engine. I'll find out when the tensioner is replaced if the problem is related.

[Jarv]

I thought we had belts?

[Jarv]

I thought we had belts?

[K2]

We do indeed have belts for inlet valves, and we have a set of chains for exhaust valves...I think, or that could be the other way around! One of the engine guru's will know which is which.
One thing that I do know is that its not cheep to repair: Main dealer says best part of £2000

[Jarv]

I was so sure I said it twice, LOL, how does that happen?

Anyway, cheers K2, you learn something new every day. Hope you get yours sorted, and at a reasonable cost!

[Golich]

I've never heard of expansion being an issue before. I have heard of a vaccum being drawn in the tank due to a blocked breather.

Do you have access to VAGCOM to check for DTCs?