Let's play a guessing game...

[ParaBul]

Today, my daily driver went to the dealer on a tow truck. Who can guess the problem before the dealer?

The details:

MY10 GTD with DSG. Just over 50k km on the clock, approaching 4 years old. Daily driver, but rarely does only short trips. For the last 3 weeks the daily commute has been 27km to work, 30km home (different routes - morning is a pretty good run, but I take a longer route home for less traffic).

The run to the office this morning was good - no hint of trouble. Half an hour after arriving, I left again to go to a meeting in town. 6km into the trip, cruising in traffic on a flat road, the engine stopped. "Engine Fault. Workshop!" with a flashing glow plug light (indicates engine fault - book says take it to a workshop).

Turn engine off and re-start, and it runs rough for less than a second, then stops with the warnings again. Fortunately I had enough momentum to roll onto the median strip and out of 8:30 traffic on a major arterial. Tried to start several more times with exactly the same outcome.

Caught a bus to get to the meeting, then back again.

Over two hours since the first fault, and it's still the same - start, rough, stop almost immediately.

RAA arrived, insisted on attempting diagnosis. Plugged in a code reader, but no codes - he showed me, it said "No codes." Tried starting several times with the code reader plugged in, still said no codes. Mechanic couldn't hear a fuel pump run when the ignition is first turned on (I never have either, but he even used a stethoscope on the fuel tank - is there one in there?) so we spent a few minutes checking all the fuses - all OK.

Tow truck came and carted it off to the dealer's workshop. They couldn't look at it when I arrived because I hadn't booked - I understand their point, but I had a chuckle at the concept of planning a breakdown. Maybe Monday.

5:15pm I received a phone call - they've spent 1.5 hours looking at it but don't have an answer. Diagnostics point to an injector fault, but injectors test OK. Next stage is check the ECU.

So - who can pick the fault before the dealer? Is there a fuel pump in the tank? Is the dealer looking in the wrong spot? Will I need to sell my car to cover the repairs (I do have an extended warranty, but are they really worth what I paid?)

There is no prize here - I'm too cheap. Play for the respect of your peers - or fellow forumites, depending on your point of view.

[Umai Naa!!]

Who owns the extended warranty?

If it's Volkswagen, you'll be ok. Let them do their thing.

ECUs do fail from time to time. 1.5hrs is not sufficient enough time to try and diagnose why the car won't run if it's not logging codes.

[Corey_R]

Mechanic couldn't hear a fuel pump run when the ignition is first turned on (I never have either, but he even used a stethoscope on the fuel tank - is there one in there?)

I'm not certain about diesels - but at least with the modern petrol VAG cars there are 2 fuel pumps. A low-pressure fuel pump in the tank which sends the fuel to the engine bay, and then a high-pressure fuel pump attached to the motor which pressurises it for the fuel rails...

[Umai Naa!!]

With VCDS, VAS-PC, etc you can operate the in-tank pump independently.

[h100vw]

Who owns the extended warranty?

If it's Volkswagen, you'll be ok. Let them do their thing.

ECUs do fail from time to time. 1.5hrs is not sufficient enough time to try and diagnose why the car won't run if it's not logging codes.

No codes but a light on? That sort of doesn't compute? Can you give us an example or something that might do that? I am interested to know, not doubting you.

Gavin

[Transporter]

No codes but a light on? That sort of doesn't compute? Can you give us an example or something that might do that? I am interested to know, not doubting you.

Gavin

The RAA most likely have only very generic scanner, which doesn't have to pick up every fault, simple like that.

[Umai Naa!!]

Yep, as per above.

Plenty of them won't even pick up misfire codes.

[ParaBul]

OK, so there should be an in-tank pump? Perhaps the RAA bloke was on to something! That could also explain the sudden stop and rough running whenever I tried to re-start it.

No further word from the dealer - I continue to wait...

[Lucas_R]

The HPFP's (high pressure fuel pumps) on the TDI's are known for failing all of a sudden. There is a thread on a USA based VW forum where people are tracking the number of failures: Official list of HPFP Failures - TDIClub Forums

This one sounds similar to your scenario;

Year: 09
Build Date: not sure (still at dealer)
Make/Model: Wagon TDI Manual trans
Tranny: DSG, 6M
Mileage: 21,???
Diesel Fuel Source: USA Gasoline
Additives: (No
Problem: (HPFP failed.... Driving last Monday, Engine Malfunction light came on and then went off. Glow plug light continued to blink. Stopped (at baseball field, probably 100 yds after lights went on)
Left for evening, no light, very faint noise in engine. Drove 50 yds and battery light came on. Stopped and car died. Cranked up and into reverse for 10 feet, died and wouldn't crank.
Towed to dealer next morning. Capital Eurocar in Tallahassee. First call they told me I put gas in the Diesel engine. I told them I had put fuel in 3 days prior and driven over 150 miles.
Called that afternoon to say they were putting some sort of fuel sensor in the following day.
Called the next afternoon to say it was put in but didn't fix the problem. Said they had a similar problem 8 to 10 months ago with another car. Told VW engineers would not be available till following week (that was Thursday) I was given a loner VW Routan at that time.
Called Monday afternoon and told there were metal shavings in the fuel. I asked where they came from and was told that the VW engineers wouldn't say. I was told they were going to replace the gas tank and many other parts and that it should be ready by Wed or Thursday (22-23 of April), unless all the parts weren't available.

[ParaBul]

Thank for that. There are some similarities, but most reports seem to include that the car ran for a while after first throwing a trouble light - mine simply went "bong" and stopped. Which is not to say that this isn't the problem...

I'm wondering if there is a problem with fuel delivery. I had filled up the Friday before, but at a Shell servo that I use often - I'm not sure that's really a factor.

The other recent change is the type of driving - for the last three weeks, the cruise into work in the morning is really a cruise. The first 8km or so is predominantly down hill, then basically flat the rest of the way - best fuel economy the thing has ever seen. Going home around the foothills starts with some climbs, but by the time I get home the average for the 30km trip is never higher than the long term average over its entire life. Could a lot of low load / low rpm cruising upset something after more than 3 years of working harder?

BTW, still no more news from the dealer...