intermittent rough idle and cuts out "save the Passat"

[wayne1970]

Guys i am at my wits end and about to get into a trip to the garage where i recon they will just go through trial and error to fix the car.

car runs 100% pulls great stops starts etc then all of a sudden it will cut out at idle (dosent cut out if moving)

i have noticed also that if it is idling and the intermittent fault occurs the engine starts to get a rough idle slowly getting worse until it cuts out. bit like it was running out of fuel.

i can restart the car just by turning it over for 30 seconds to a minute. when it dose restart, it sounds as if you were bleeding the system after you had changed a fuel filter.ks a few more times then fires on more and more cylinders.
if this happens to many times in a short space of time it flattens battery and i have now had to call AA to start.
first guy said it was low on fuel stuck a gallon in and put his boosters on (off course it was going to start after the 30sec - 1 minute cranking) but he insisted it was faulty gauge.
second time i managed to get car started before they arrived. both times they tried to put on their computer but could not get any issues.

car was serviced about 3k ago all filters etc.
I changed the engine temp sensor. as it was similiar to an old issue i had before but this time it dosent wait till it is up at 90 degrees.
and I have changed the lift pump in the tank (was a bit gunked up from 200k+miles of fill ups)
checked fuses and relays no smell of burning from fuel pump relay (getting a new one in morning just incase)
had a look for any perrished hoses or chaffed wires but nothing visible
tonight car did have a bit of greyish smoke when first started
had it on VCDS a couple of silly errors and glowplugs but nothing that jumps out that would cause this issue.
I can do basic checks on VCDS but i may be looking in wrong place.

my first thought was fuel and in checking i noticed that the fuel filter housing seemed to only fill up about an inch to 2 inches but since changing the pump it fills up more and when i pull of the pipe their is pressure.

any thoughts before i start pulling out injectors to be checked or taking cat of to see if its disintigrating causing a temp blockage.

or some one to tell me how to get more info out of the VCDS would be great.

[rowdy-999]

Engine type/code etc?

[wayne1970]

woops new i missed something

2007 passat 1.9 tdi BXE

[philipharmes]

From the symptoms would have said it was either the in-tank pump or its 12v supply intermittently failing, but you say the pump has been replaced.
Was it a new pump?

When it fails again you need to check it has 12v accross it when cranking & that it is pumping.

[Majorlook]

If you have a voltmeter, check across the battery terminals and see if the voltage is high enough, My 2008 2.0tdi CBAB is having very similar issues to yours right now, so far I've found that whilst running my car is only producing around about 13.1-13.2v so I'm going to have a go at replacing the alternator.

The AA guy also said to me it was the fuel pump, I tested out mine and the resistance values of the new one was very close to the resistance values of the old one so I decided to return the new one. After charging the battery my car starts maybe after 2 or 3 cranks then it runs for maybe a few days fine and then I'll start it and the idle will go rough and then it'll just die and the battery will be on about 11v.

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