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I have a Golf PD150 with 13k miles. Goes like a train and consistently getting nearly 50mpg. However, under load, particularly when hot, I'm experiencing a slight misfire. VW have checked and diagnostics show up nothing amiss. The problem started when the car was filled with petrol instead of diesel and driven. The tank and fuel lines were properly drained by VW and I was informed there would be no further problems. This all happened 2-3k miles ago so I thought any petrol still sitting in the tank would have gone by now. Anyone experienced anything similar or any idea's how to cure?
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Was the fuel filter changed? - the petrol may have caused some internal damage to the filter. Probably a long shot.
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No, the fuel filter was not changed - they said up front they would do it as a matter of course.... but ultimately they didn't. You reckon this can cause the symptoms to which I refer?
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Hello Phidman.
The problem started when the car was filled with petrol instead of diesel and driven.
How far was it driven?
Was it then stopped or did something unexpected happen?
Your car is a high-compression diesel, with variable vane turbo and sophisticated electronics.
I'm worried that injecting petrol into a cylinder and compressing at approx 20 to 1, versus 10 to 1 in a petrol engine, would cause hot spots on valves, inside the oxidation catalyst on the exhaust etc.
Tell us a bit more, please.
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The car had about 1/4 to a 1/3 tank of diesel that was topped up to full with petrol. It was then driven about 100 miles - no real performance problems but mpg was averaging less - perhaps low 40's. It then stalled as I exited a dual carriageway and entered a roundabout. It was then turned over a number of times but did not start. After which the tank and petrol pipes were drained by VW. They advised that no permanent damage should have been caused. The misfire has been ever-present since - initially I just thought it was a little bit of petrol still floating around but after 2-3k miles it hasn't disappeared. I haven't ran the fuel to almost empty.
Symptoms are a slight misfire under acceleration (at higher speeds) or going up an incline.
As mentioned earlier, VW have ran diagnostics but could not find fault. Would the problems you identify or a damaged fuel filter cause these symptoms and could they be missed by the diagnostics?
Thanks
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100 miles would be more than enough to wreck the valves and hot-spot the oxidation catalyst.
I'm very sorry to be the bearer of bad news but you have serious engine damage here.
If you think of running a high performance petrol engine on low grade fuel and the detonation (pinking) you get with that, you'll realise what running petrol at almost 20 to 1 compression will do.
I'd forget about the filter. A known starting tip on diesels is to mix 1 gallon of petrol in a tank of about 10 galls diesel to stop fuel waxing etc.
Therefore, a small amount of petrol in your diesel will cause no harm. After 2k miles it'll be gone, anyway.
What I'd do is forget your VW dealer. Seek out a proper Diesel specialist and get them to sort it. Or, live with it.
This won't be a cheap fix, i'm afraid.
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Thanks for your help Sean.
My local VW dealer doesn't know it's had petrol in it - at least I haven't old them. The draining, etc was carried out by another dealer. I didn't tell them in case it affected the warranty. Would they be able to tell if it's had petrol in it? If so would they be able to say when? Do you know whether VW have a central database with each vehicles service/repair history? I've only had the car 3-4 months and could argue it's been like this since I've had it - in which case they either repair it or provide me a replacement - under warranty. Not completely honest, but based on other comments about VW dealers elsewhere in this forum, it would be some form of justice.
Ultimately it's only an intermittent problem that doesn't affect most types of driving so it could be lived with. However, it would be nice to get sorted and get VW to foot the bill.
Last question, what represents a not 'cheap fix'?
Thanks again.
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This has been bothering me all afternoon.
I've worked for VW at Wolfsburg, and rang a couple of colleagues there for you.
They were quite shocked that 100 miles could be covered on petrol, particularly as the PD engine is fitted with extreme pressure "Unit Injectors" ie pumpe deuse.
The comment was that the exhaust valves and injector nozzles would glow white hot.
If you have been near any VW appointed dealer, the work is on computerised database.
Warranty claims would be closely examined and I recommend you play the game. Deceitful behaviour may result in much trouble.
The comment I've got was that VW technical think you may get away with re-nozzling the injectors. The excess heat will have melted the ends and distorted the spray pattern. if that's the case, the bill will be £600 ish, plus labour.
If you're unlucky, the head will have to come off. Revalving is likely to be £400 plus labour.
Injectors alone are seen as your best start point.
None of this shows on the diagnostic unit as the fuel pressures etc will be in range. it's the pattern that is off.
Hope this helps you, mate. Good luck.
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The car had about 1/4 to a 1/3 tank of diesel that was topped up to full with petrol. It was then driven about 100 miles - no real performance problems but mpg was averaging less - perhaps low 40's. It then stalled as I exited a dual carriageway and entered a roundabout. It was then turned over a number of times but did not start. After which the tank and petrol pipes were drained by VW. They advised that no permanent damage should have been caused. The misfire has been ever-present since - initially I just thought it was a little bit of petrol still floating around but after 2-3k miles it hasn't disappeared. I haven't ran the fuel to almost empty.
Symptoms are a slight misfire under acceleration (at higher speeds) or going up an incline.
As mentioned earlier, VW have ran diagnostics but could not find fault. Would the problems you identify or a damaged fuel filter cause these symptoms and could they be missed by the diagnostics?
Thanks
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For gods sake, as Sean says, come clean! This could take many hours of fault-finding!
I don't think VW will honour any warranty claims....I wouldn't blame them either.
I'd also expect (as Sean says) to find melted injectors and possibly damaged valve seats - 100 miles is one hulluva long way on Petrol...
Part-exchange time, Sir?
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Just for clarification, there was a reasonable amount of diesel in the tank before the petrol was added. Would the two fuels have mixed together or would the diesel have burnt off prior to the petrol?
Also, as stated the symptoms are reasonably minor - if not regularly irritating. The fault you describe sounds fairly major and to a layman like myself, seems like it would affect the cars performance more frequently or all of the time.
In terms of progressing with VW - clearly they do not have your technical knowledge. At the time of the incident they informed me that there would be no long term damage. Based on their (what now appears to be) naievety, do I need to lead them by the nose on this one? i.e. not only tell them about the petrol incident but tell them I have been advised that the injectors may be at fault.
One last point, presuming they have a database I would imagine that they would check the car's history if any fault is reported. If this is standard procedure it leads me to wonder whether the tank draining work, which as I mentioned earlier was carried out by a different dealer, is actually on the record.
Again, many thanks for your help.
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Phidman,
I spent time and my own money phoning Germany for you yesterday. I will not be party to any fraudulence.
You said 1/4 tank of diesel 3/4 petrol. This is not "a reasonable amount of diesel" in the mixture.
Both fuels are petroleum distillates and would mix.
It is NOT TRUE that you have progressed anything with VW. I spoke to VAG, milton Keynes this morning.
You have probably contacted a VW dealer. Not the same thing at all. Most dealers say there would be no perceptible damage in cases of fuelling errors, but I bet you didn't tell them the vehicle travelled 100 miles. I have never come across such a journey travelled as this before. Neither have VW Wolfsburg.
If you are intent on defrauding VW, your choice Sir, but there is now a Q10 marker on cars of your type, looking for just such a claim, and the penalties for fraud include imprisonment.
That would be pure theft and, frankly, I am ashamed of you.
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Apologies Sean - I appreciate all the help you have offered.
I have no intent on defrauding anyone. However, I am keen to layout as little cash as possible to rectify the problem. I know in my area there is a good independent that charges half the labour costs of the dealership. Looks like going through them will invalidate the warranty though.
With regard to progressing with VW, all my comments refer to what I was told at the time of the incident by VW Assistance and the dealer who drained the system - all of whom knew I had driven 100 miles. Their exact comments (consistent to both) were if the car restarts and runs, it'll be fine.
Since then it is true to say I have not tried to progress - my comments around how to approach VW were actually a compliment to your obvious knowledge versus the advice given by VW at the time of the incident.
Again - apologies and thank you.
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