2007 Golf TDI Cutting out

[BurrenD]

Good morning all,

New member here, I've joined in the hope that someone may be able shed some light on an intermittent problem I have with my car. Kind of a long post, typed on my phone which was a pain in the @rse.

The car is a 2007 Golf GT Tdi with a BMN engine (170). I've had it over 3 years and there are 167k miles on it, had about 125k on it when i bought it. DPF and EGR both deleted before i got the car. Injector recall was also done sometime before I got it.

The problem is the car cuts out or attempts to cut out causing a kangaroo effect if you like. As it's doing this a relay under the dash can be heard clicking on and off as it cuts out briefly and then regains power. If I'm at a low speed there is a good chance the car will cut out but it usually restarts although one time it did take a while.

Due to the sound of the relay clicking at the same time as the loss of power or cutting out I am looking at an electrical fault I believe as opposed to fuel.

The dash stays live during this, I have checked for fault codes in all systems but no codes, I'm using a sn@p on scan tool. Communication with the engine ECU seems to remain after the engine cuts out, I can still see live data and would normally not expect to if the ECU had lost power.

I have done a brief check (visual and moving wiring with engine running) on wiring at the relay panel under the dash, wiring going to engine ECU engine bay fuse box and also the dashboard but can't see any obvious faults.

This problem occurred briefly during the summer and magically disappeared but has now come back with a vengeance. Hate those faults that seem to fix themselves. I'd also be happier if the car would just stay dead after cutting out as it would be easier to find the fault.

Any help or advice would be appreciated, I've lost all confidence in the car and this latest issue has made it pretty much undriveable. ( it has a few fuelling faults common to this engine which I havnt gotten around to fixing, time and patience)

Thanks

[BurrenD]

So I had another look at this since my post.

The relay that's clicking is the fuel pump relay as far as I can make out. With the relay removed the car will start, also removing the relay while is running does not cause it to cut out, only left it out for a few seconds. I've also swapped it with another relay and the problem still occurs. All this means that the relay clicking is another symptom rather than a cause.

So I need to go and find a wiring diagram to see exactly where this relay wiring goes.

Fingers crossed it doesn't end up being an engine ECU problem...

[BurrenD]

So I had a look at the wiring after talking to a friend of mine who reminded me that I'd repaired a similar problem on a Passat a few years ago.

Checking the wiring that runs in front of the gearbox and under the manifold i found a wire that broke easily and caused the car to cut out. A fault for the crankshaft sensor showed up on the scan tool.

Interestingly the car started after a bit of cranking and ran with a high idle even with the wire broken.
I've repaired the wire and test driven and the fault is no longer present.

I'll update if there is any change.

[ChicksFan]

Well done for sorting it out yourself. Your friend deserves a pat on the back too.