S4 AAN cutting out while driving

[mcandmar]

Check your battery terminals for a bad connection, i.e. take them off and clean with a bit of sandpaper. I had issues with our S4 where it wouldnt start every now and again, i tought it was a dead battery but it turned out to be oxidization on the terminals.

[Knight Rider S4]

Not good Andy....that never happen with me on the car ...if you want to bring up to me when i am back from HK ,I will scan for you and see what code it comes with .....If its fuel relay have loads of them about so no problem fixing

[saltinot]

I agree with the topsparky, the first step would be to check for DTCs.

I've had a timing/engine speed sensor cause a similar problem. If so, there will be a DTC there.

[UrS4boy]

Fuel pump relay is a possibilty,can't remember if it is under the bonnet in the black box near the window or below the steering wheel on an S4 though.

The J17 fuel pump relay is VERY important to the running of an AAN. Not only does the ECY use it to control the fuel pump, it also routes power to the five N75 wastegate frequency valve, the five injectors (which get their duty cycle control from the ECU), the idle stablization valve (N71), the emissions carbon cannister frequency valve (N80) and the oxygen sensor, as noted here:

http://forums.audiworld.com/s4s6/msgs/133907.phtml

Clicking = a failing relay = your most likely suspect.

[topsparky]

possible lambda problem too
get it on vagcom mate

[Ruffiano]

Sounds like a coil to me.

[spink]

Fuel pump relay is a possibilty,can't remember if it is under the bonnet in the black box near the window or below the steering wheel on an S4 though.

[Andy128]

I'll try this forum first....

Had my urS4 out last night for a 60 mile journey, everything was fine for the first 30 miles right up to the point where the engine cut out completely while in the fast lane of the A9 dual carriageway.

Fortunately I managed to coast into a handy lay-by (which was damn hard with no steering). No warning lights or the like came on until I was nearly stopped, when the battery light finally popped up. I turned off the ignition, swore a bit, looked for a change of underwear then tried re-starting. It fired up first time

It died another three times on the rest of the journey, then another six times on the return trip this morning (again starting after about 30 miles). Each time it fires up first time after dying. Did it twice in one mile today. In between it drives fine.

Its appears not speed related, having happened at ~80 mph (the first time) then as low as 40. It also appears not rpm related, I tried running in 3rd at 4000 rpm but that didnt help. But it does seem to only happen while running at a constant speed. I did the last 10 miles today accelerating to 75, then coasting to 60, then accelerating etc etc without the problem re-occurring.

I also noticed this morning that after the engine cuts out and I'm rolling to a stop, there is sometimes a repeated clicking noise from under the steering wheel/dash area like a relay going off.

Any ideas/suggestions?????

Cheers
Andy