Wrong Diagnosis of Fault?

raymoto

VW Tiguan, at about 4 months old, began to have momentary cut-outs during normal driving: completely off for 3-4 seconds then back to full power again.
Garage diagnosed fuel contamination, and warned me I'd have to pay for a full fuel system replacement at almost £5000. I reluctantly rang my insurance company, who said they'd cover it subject to Assessor inspection. The Assessor told me he thought there was nothing wrong with the fuel system, but he authorised replacement of the fuel pump (£1000) in case it failed again in a dangerous location and he got the blame. Note that there was no visible evidence of a fault and no swarf in the system.
With the new fuel pump fitted, I drove away, and EXACTLY the same symptoms occurred. Clear proof that there was never anything wrong with the old fuel pump?
I drove home on limp mode, and next morning, the car wouldn't start. VW Assistance engineer found EGR valve stuck open, diverted exhaust, and got me away, with full power, and with no more cut-outs. Clear proof it was the EGR sticking momentarily on its path towards total failure?
No, says VW garage. There were TWO faults, they say: the one we cured by replacing the fuel pump, and one caused when the EGR valve stuck open. (A warranty item). That's two faults, then, immediately after each other, with EXACTLY the same symptoms. Anyone believe that?
I've been advised by five experienced mechanics that my symptoms were not typical of fuel contamination, but VW garage and VW Technical Support Team say they were! (Fuel contamination is more likely to be poor starting, rough running, misfiring, sluggishness and poor performance - NONE of which I experienced).
My filling station (Tesco - local and national) say they've had no complaints of problems at my filling station. Just me then - out of thousands of drivers using the same facilities.
Two local on-line chat forums gave plenty advice about supermarket fuel, but not one person knew of anyone local who'd experienced problems locally - just me then!
VW garage say a fuel sample ignited in a dish, but they couldn't show me or the Assessor because they's thrown away all the fuel. Nor could they show me the allegedly faulty fuel pump, because it went back as an exchange item.
I've lost my No Claims Discount and my £250 excess. My insurance premium is likely to increase for some years.
Does anyone have any advice on what, if anything, I can do next?

Scottie_dog

Hi, this may be just a coincidence, but I had the same problem with my 2007 Audi A3 1.9tdi. When I got the car it ran perfectly well. 4 months later it started cutting out for 3 or 4 seconds and I lost count of the times it went into limp mode. I had it in various garages, no one could find a fault, nothing was coming up on the diagnostic machine. It went in to limp mode for the last time when I was overtaking a lorry on the A1. Scary. I took it to a local old school type garage who specialise in audi/vw. They advised it was tesco diesel. I thought they were having a laugh. They drained my fuel tank, filled it up with diesel from Shell, warned me to never ever put supermarket fuel in my car again. After about a month, I realised they were right (I was obviously skeptical about their diagnosis) and 18 months later I have never had any more problems. Touch wood :-)

Nilrem

Supermarket fuel is very very unlikely to be the cause to be honest, if it was there would be hundreds/thousands of these issues every single day.

It is however very easy for a garage/manufacturer to blame the fuel because they know it's going to be nearly impossible to prove otherwise, certainly by the time the vehicle has been repaired (probably disposing of the fuel in the tank at the same time).

All fuel in the UK has to meet very strict standards, if any car manufacturer is telling you that standard fuel (IE unleaded when the car says it takes unleaded) is unsuitable and at blame, they're either talking **** or hiding a problem with their design*.

Or to put it simply.
A car sold to take fuel of a certain standard in a certain country, should be able to take that fuel regardless of it it's sold by a supermarket or a "chain". If there is an issue with the fuel and the car, it's as likely/more likely to be a design issue with the engine/fuel system than the actual fuel, especially if it isn't affected everyone using that fuel.

The problem is, that once a problem is "fixed" and people have been told to avoid X supplier, they're going to link the two events, it's like saying that your football team won because you were wearing your "lucky" boxer shorts.

Raymoto, I don't suppose they actually sent the fuel system or anything away for a proper analysis when they blamed it on teh fuel?
Unfortunately that would have been about the only way to show it was the fuel conclusively, but by the sounds of it they were more interested in simply throwing parts at it (probably easier/better profit for them to replace 5k worth of parts in a go than actually find out which part was faulty and why).


*IIRC there was a problem with the design of the fuel injectors in one range of engines which was constantly blamed on the "super market fuel" until long after thousands of people had paid for replacements, when it turned out it was an actual design flaw after enough people noted the number of problems and fought it.

loskie

can you insurer not assist in your fight against VW

bigjl

The funny thing is I have never heard of anybody having injector or fuel system problems when they have never used supermarket fuel.

And the old argument that all fuel is the same is a moot point.

As with genetics it is the last few % that mskes the difference between a halibut and a human.

arcon5

Do you have the old pump? If so have it tested and inspected by specialists.

BeenThroughItAll

I'm not going to bother re-typing it all over again, but the likelihood of supermarket fuel being the reason for any of these failures is infinitesimally small. If fuel was the cause, it would be just as likely to have come from the Shell garage up the road as the local Tesco. The only reason people blanket blame upon the supermarkets is because of the sheer volume of fuel they now supply to the UK market - statistically speaking there's a much greater chance you'll have filled up at a supermarket if/when there is a fuel issue, and also that supermarkets are much more likely to end up with problem fuel since they have so much more regular deliveries than other stations.


I previously went into a lot more detail in this thread (posts #14, #21 and #24, specifically).


https://forums.moneysavingexpert.com/discussion/comment/66966529#Comment_66966529

colino

So someone authorised a £1000 bodge thinking maybe, just maybe fuel contamination had wrecked the HP pump? What about the rest of the contamination from the filler neck, through the tank, filter, pipes and injectors?

Nilrem

bigjl wrote: »

The funny thing is I have never heard of anybody having injector or fuel system problems when they have never used supermarket fuel.

.

And how many people have never used supermarket fuel in their car these days:)

If it was "supermarket fuel" you'd expect far more people to have the issues given that it would either have to be a single load at fault each time (in which case anyone filling up that day would be affected), or it would have to be a consistent low level thing, in which case there would be large numbers appearing consistently over time.

If it is the supermarket fuel only causing these issues why aren't the manufacturers of the cars coming out and saying so publicly and calling on better controls and tighter regulation, surely they'd have the stats, and they and the insurance companies would be making a big thing about it backed up with detailed information and testing.
I'd even expect the insurers to start putting on their application forms a question about where you fill up if it was that bad an issue, and load the premium accordingly.

All I ever see however from the manufacturers is things like "use high quality unleaded RON XX unleaded", which covers every unleaded in the UK (our fuel is higher quality than many parts of the world), or "BMW recommend Shell"*, which would imply that Esso and Texico would be as bad as Morrisins and Asda.
I don't think, except in a few high performance cars (which typically state to use "super xxx"), them to state anything like "do not use supermarket fuel", which is odd if Supermarket fuel is so bad for the engine that their dealers and mechanics know instantly that X problem is going to be caused by it.


As colino says, replacing just the fuel pump for a "fuel contamination" issue is pretty nuts, given that if it was bad enough to kill the pump it would probably have caused issues in all sorts of other places (the pump is, from memory a lot more tolerant of variable conditions than say the injectors, and the filter would have picked up a lot of contamination.

Besides anything else, if it was fuel contamination and they were sure of it, they should have kept a sample of the fuel for testing - IIRC if it was bad enough to cause the engine to have issues, it would not have met EU/UK standard and thus could/should have been reported, and the op would likely have been able to claim for it from the filling station.




*Whichever petrol company has got the current marketing tie in with the car company.

Strider590

Nilrem wrote: »

All I ever see however from the manufacturers is things like "use high quality unleaded RON XX unleaded", which covers every unleaded in the UK (our fuel is higher quality than many parts of the world),

No, it's not.

Fuel in Europe and America has bio-ethanol, which reduces power and increases fuel consumption, as well as damaging fuel lines, injectors fuel pumps and fuel tanks.

Basically, because octane rating is quite literally a measure of the fuels quality (the ability to give a clean/controlled burn), Japan have 100ron fuel, you can't get much better quality than that.........

BeenThroughItAll

Strider590 wrote: »

No, it's not.

Fuel in Europe and America has bio-ethanol, which reduces power and increases fuel consumption, as well as damaging fuel lines, injectors fuel pumps and fuel tanks.

Basically, because octane rating is quite literally a measure of the fuels quality (the ability to give a clean/controlled burn), Japan have 100ron fuel, you can't get much better quality than that.........

But our fuel is, as stated, higher quality than many parts of the world. Notice the previous posted didn't state 'every other part of the world.


Take pretty much 100% of African countries. Our fuel's better quality than theirs. Then there's the USA, where 95RON is considered 'premium'. Then add in much of South America.


That's 'many' in my book, and I haven't started on Asia or other parts of the world.