My new Bluemotion (supposedly more economical but in fact only 35-40 mpg) has from new occasionally had a momentary but sometimes quite sharp 'catch' in the engine power accompanied by a strange noise like a distant dog barking. This has grown gradually more frequent until in happens > 1/minute. I have a sonogram of the under-bonnet sound showing that this occurs at high turbocharger speed and involves a sudden turbo speed drop.
VW originally diagnosed this (after the garage confirmed the effect) as a faulty EGR valve. When the garage replaced this (under warranty) without any improvement they asked for the valve to be blocked off. According to the garage (unfortunately I did not test it) this stopped the effect, and VW now claim the effect is normal 'EGR bounce', a term I cannot find on the web and which I suspect they just invented!
I have driven VW Sharan diesels (2 before, I am sure they had EGR valves!) for >10 years and never experienced anything like this - has anyone heard of it?
It may be unrelated but I am also very disappointed with the fuel economy - only 35-40 mpg which is a little worse than my previous 10-year-old version and hardly justifies the 'Bluemotion' label! (& the extra price). I note that the garage say the old EGR valve was very carbonised after only 8 months.
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you don't say how many miles it has covered as to whether its still tight reducing the fuel economy
there have been some issues with EGR resonance causing various issues.
Do you stick to the same brand of fuel or use anything ? & is your driving local or long?
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About 9000 miles. Fuel is whatever is available locally! I am in a rural area so a typical journey is probably about 10-15 miles with probably more than half the mileage on >60 mile journeys. The monitor can be reset after the car is warmed up so a 60 mile post-warming motorway journey that gave about 43mpg on my old car gave 41 on the Bluemotion. Surely that is not much worse but it is supposed to be better!
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I would reckon the engine will still be tight, a good 20k before its at its prime. Sounds daft but i will stick my neck out & suggest you try one of the top three brands of fuel ie Esso BP shell & stick with it for a few tanks & see if any improvement. Also i think you runs are to short for a diesel, this will create extra gumming around the EGR as will some rural fuels.
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I have an Alhambra Ecomotive, so it's the same. Very occasionally we get what can only be descibed as a hiccup whilst accelerating. Checked with a friend who has the Passat with the same 140 engine and DPF. It also does the same trick. Do PD engines not like the DPF?
Drivingwise, you've got to grt that oil temperature gauge to the middle before registering good MPG, so thats at least 6 to 7 miles of relatively clear driving.
You'll hardly ever need 6th gear except on the open road to keep the revs at 2000 or over to keep the DPF regenerating.
I like it as a car but it takes some getting used to.
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