Ocasssonally cuts out (UrS4 auto)

[quattrokid2]

The car isn't used much ... (it's been sorned since April) but over the past 3 years since it had a big overhaul it has developed a bad habit of cutting out while driving. Firstly it hesitates then the revs just dies away until it stals, the ignition switch was changed in March but it's done it twice since then most recently yesterday getting the car home from its storage hidy hole.

I'm going to get the imobiliser removed and see if that makes any difference, once it stals and the ignition turned off, the engine restarts on the first attempt and then it's fine for days or even months then without warning 👀

I'll vag com it when I get the chance as well, but any ideas other than an interfering imobiliser possibly being the cause, what if it's not the imobiliser what else could it be folks?👍🍻

[geneandbolly]

come on you lot - any suggestions to help my ayrshire tattieheadit chum??

[martinws]

Could be hundreds of things. Vagcom first, to see if its an ECU telling the car to stop for some reason. Could also be aftermarket alarm cutting the fuel pump feed or just a knackered fuel pump.

Pull codes next time it happens and let us know.

[UrS4boy]

Above the C4 UrS ECU fuse panel and related issues

come on you lot - any suggestions to help my ayrshire tattieheadit chum??

His signature flag says he's a Yank.

(BTW: My clan (Ferguson) has ties and history all over Ayrshire, including Kilkerran - South of Ayr, bit south of Maybole. Not to far from Patna (where great grandfather John Forgie is/was buried) and Dalmellington where some of the Forgie family info can be found at the registry office (at least it was when I was there in 1976).


Anyway, back to the plot: intermittent electrical faults are terrible to find and fix. Once it really fails, then it is easier.

Could be anything but it sounds very electrial ground/earth problem-like. I would have said ignition switch but supposedly it was replaced with new not too long ago.

Check the ignition to head and intake manifold grounds and the ground strap from the engine to the chassis (under the turbo) for starters.

Other issues include the thermal breakers above the UrS4 ECU. Sometimes they fail in strange ways. Better to replace them with normal spade fuses to eliminate them from the list of usual suspects.

More info about the Above ECU Fuse Panel:

http://forums.quattroworld.com/s4s6/msgs/137287.phtml

[quattrokid2]

Cheers guys👍🍻

How the hell did I become a Yank ?👀 been s few times but I wouldn't want to be one 😂

I'll dcan it next time I'm home, see what's going on, it's as if a switch is made , the engine hesitates then dies but bring an auto the engine is dragged down the revs by the box, as soon as its stationary and the engine turned off at the ignition and restarts straight away, not much time for snything thermal of otherwise to cool down

Hmmm!!

[UrS4boy]

How the hell did I become a Yank ?

The S2Forum runs in vBulletin. The vBulletin default country is the USA when you sign up. You need to edit your profile to show the proper flag of the country you are posting from, not just the default vBulletin USA flag - helps us when we know where you are.

Click on "User CP" in the left margin at the S2Forum home page and then Edit Your Details under "Your Profile", click until you find the equivalent of this:

[quattrokid2]

Will do 👍🍻

[spink]

Did you ever swap the fuel pump relay?

[bluequattro]

I'd change the thermal fuses anyway.
An s4 I had did similar to OP , leaving me stuck on a very busy dual carriageway, in the dark, on the wrong side of a bridge.
By the time it had been towed to recovery yard the breakers must have cooled and I drove it home.

[quattrokid2]

Hi mate,no I didn't change the fuel relay,🍻bluequattro I'll look into those thermal fuses👍
I'm gonna to use the car over winter so I need to make sure it's 110% reliable again before I trust it out on the road!

Spink,have you got the part numbers for those thermal fuses please and I'll order some 👍🍻


I still haven't sourced that distant foghorn noise either which is also getting on my **** 😤

[bluequattro]

I just put normal blade fuses in, high amps I think.
Never had a fail afterwards.
Mine did it over winter, after about 30 mins driving, I think the fuses overheated, heaters on etc

[AndyD]

(BTW: My clan (Ferguson) has ties and history all over Ayrshire, including Kilkerran - South of Ayr, bit south of Maybole. Not to far from Patna (where great grandfather John Forgie is/was buried) and Dalmellington where some of the Forgie family info can be found at the registry office (at least it was when I was there in 1976).[/img]

Small world my dad lives in Patna and used to run the Doon Tavern pub in Dalmellington.

Anyhow sorry for the thread drift......

[quattrokid2]

Your dad may know Sam & Isobel Kerr, the undertakers in Dalmellington?

Bluequattro, could you explain what a thermal fuse does please? Is it a circuit breaker between certain temperature conditions and snything above that temperature it opens ?

Under normal conditions what's getting so hot that it opens a thermal fuse? What's it protecting ?

How many earth straps are there ?

[geneandbolly]

Your dad may know Sam & Isobel Kerr, the undertakers in Dalmellington?

Bluequattro, could you explain what a thermal fuse does please? Is it a circuit breaker between certain temperature conditions and snything above that temperature it opens ?

Under normal conditions what's getting so hot that it opens a thermal fuse? What's it protecting ?

How many earth straps are there ?

jeeeesus!! do you ever sleep??!! i am gubbed and have had 5 hours - you must have had around three!!?

[UrS4boy]

Spink,have you got the part numbers for those thermal fuses please and I'll order some

What part of this (below) didn't you understand?

...Other issues include the thermal breakers above the UrS4 ECU. Sometimes they fail in strange ways. Better to replace them with normal spade fuses to eliminate them from the list of usual suspects.

More info about the Above ECU Fuse Panel:

http://forums.quattroworld.com/s4s6/msgs/137287.phtml