Hello All,

I have done a similar thread before to this, but I have started to monitor cars behaviour and hopefully try get to the bottom of this.

Ever since I got the car, occasionally the car will decide it will cut out for no apparent reason. It usually happens when slowing down so going from 3rd to 2nd at low speed, the engine will just cut out and you look down at dashboard with battery light showing. It starts on first turn of the key and on we go.

However, I have now started to realise when it does it and I am prepared for it. The only ways I can describe it is if you are keeping the gas at a steady pace - you can feel the car revs very jerky and jumping. If you rev the car very slightly or when letting off the gas, you have hear like a back pressure sound going through the exhaust - like wooosh sound going back with a deep tone! (Sorry, best way to explain it). Once it's cut out, car drives fine again.

The car cut out today twice on way to work and then 3rd time start, the sound of the exhaust and jerking went. The last time it did this was on 40,400 miles, now just hit 43,000 so quite a while ago.

Car has been diagnosed, no faults whatsoever. Injectors have been replaced, serviced on time every time. Fuel Filter 'apparently' last changed in December 2010 just before I bought it.

Could it be fuel filer/thottle body related? Car is a 07 '56 Leon 2.0 TDI FR 170.

Anwsers on a postcode please

Cheers,

Luke

you don't have a bust turbo hose do you because that would cause a whoooshing noise and poss car to cut out when clutch depressed

Wouldn't I notice a drop in pressure though on the turbo?

clutch cable maybe ?

I'd try a fuel filter first!

I wonder if it's DPF re-gen related. That would fit 'car revs very jerky and jumping', different engine / exhaust sound and the problem going away straight after it cutting out and being restarted (re-gen cancelled).

I wonder if it's DPF re-gen related. That would fit 'car revs very jerky and jumping', different engine / exhaust sound and the problem going away straight after it cutting out and being restarted (re-gen cancelled).

Very true nick, I had similer symtoms with the old style exhaust pressure sensor.

I wonder if it's DPF re-gen related. That would fit 'car revs very jerky and jumping', different engine / exhaust sound and the problem going away straight after it cutting out and being restarted (re-gen cancelled).

I honestly cannot remember last time the car re-genned at 1k revs. We changed the exhaust pressure sensor in March on 40300 miles and it's done 43200 now and still no sign of a regen at 1k revs. Although I have done quite a bit of driving at 2k+ on motorway since.

That sound like my car going when it needs a regen. I get a jerky throttle response, when on steady revs and it has cut out twice when I slowed down to stop, this was before i had a new pressure sensor fitted.

I still get the odd jerky revs when at constant throttle when it wants a regen. But no cutting out.

Yep, sounds like the car is mid DPF regen to me.

My Octy has cut out twice in exactly the same place on my 70 mile commute.

The fuller the DPF gets the more it'll try to regen and the more chance there is of you interupting it.

On the way home I stick to 3rd and 4th instead of 5th and 6th. The problem then goes away for a good few months.

Cheers mate, seems I am getting closer to the cause of this now.

It hasn't done it for 2 months, so that could explain it and not done any major motorway mileage for 2 weeks. it has the newer pressure sensor too.

Hello All,

Quick update - the car made the exhaust sound and jerky today. I can now see why it's more of a DPF issues.

Anyway - I sat in the car whilst it was running like this but it was revving at normal idle speed and then few minutes later.

Is it possible that it's regenning without the revving higher? I presume now it would have shown a fault with the DPF if not been cleaning correctly.

The car regens the DPF by altering the fuel mixture. If your journey today met the requirements for a regen (over 60kmh & 2,000rpm) it will have started to alter the fuel mixture to increase the heat in the exhaust to allow the DPF to burn off the soot.

If the DPF was interupted during the regen then the fuel mixture is all to pot so the car may well run rough or lumpy for a few minutes or stall completely.

Edited 30 May, 201214 yr by silver1011