Hi everyone and thanks for your help (in advance).

I've owned my current Superb for around 18 months and have had no problems whatsoever, subsequent to this I'd owned 3 Boras for 11 years so wanted to stay within the VAG due to the reliability of their cars (clocked over 400,000 miles with VW).

About a week ago i was at a roundabout and starting to pull away when the engine lost all power, with my foot firmly on the gas (saves spelling accelerator all the time) it was slowing down, i lifted my foot from the pedal and put it down again and the car carried on as it should. This subsequently happened approximately 15-20 times over the next few days (as soon as it happened i booked it in with local mechanic who does all work on my car). So the mechanic gets it yesterday and says the vcds or similar code checker tells him there's a problem with the egr valve. Rather than replace it he took it to a place in Baildon who ran Terraclean through it (still not sure whether the egr was faulty or just gummed up as will happen with mileage at 105,400) Car runs like new but the problem is still there. I don't mind paying £120 to get my car fixed but don't like spending money for something that's still broken. Any help you great guys could offer would be brilliant. We have a VW specialist (Chris Humpleby) in Bradford who is a complete genius when it comes to fixing problems so all is not lost but I like these forums as they're always insightful.

Regards

Kieran

Bit more detail (waffled on a bit up there)

When it loses power it's as though the engine has been switched off, so pressing your foot on the gas pedal has no effect whatsoever. Sometimes lifting your foot off the pedal and putting it back on resolves the issue whilst at other times you have to dip the clutch. On one couple of occasion i've had to work down from 4th to 2nd to get moving but this isn't the norm. Never does it at motorway speed and tends to do it more under load usually in 2nd or 3rd but never in 5th or 6th.

Car is 2009 (09) Superb se 2.0 tdi . No mods.

Symptoms do fit the profile of a sticking EGR valve. Not sure how specific his code checker was on the actual fault, but a faulty high pressure fuel sensor can show identical symptoms on a common rail engine - don't know about a PD though.

Thanks for your prompt reply. The guy I took it to in Bradford who is usually really good at diagnosing faults couldn't find any as his machine said there weren't any! This has stumped him as well and he specializes in VAG cars. It certainly doesn't do it as frequently since I had it Terracleaned and whether it's just a coincidence it does it less if I use excellium fuel than if I use standard diesel.

As always thanks for your help.

Kieran

When was the fuel filter last changed Kieran?

Faulty brake pedal or clutch pedal switch?

Or faulty accelerator potentiometer?

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JakeBlade: Fuel filter changed at last service 3500 miles ago.

Andyvee : Mechanic mentioned this but was reluctant to replace parts willy nilly without being sure (nice to see). I'll speak to him again about this though.

Thank you both very much for your prompt response.

Kieran

Faulty brake pedal or clutch pedal switch?

Or faulty accelerator potentiometer?

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I have had a similar problem before though I must admit it was on a Renault 25 some 20 years ago.

Thanks Danny, appreciate your help.

Kieran

Unlikely to be faulty accelerator pedal as it has a double-redundant system. Brake switch is likely, as could be EGR.

For those interested in the accellerator, see this picture (shows old style firewall mount pedal but the internals are the same):

Hi,

My first guess (yours being a diesel) would be air in the fuel. If your fuel filter was changed as you said then check all the connections on the fuel system then bleed the system. Second guess would be the turbo actuator not working properly if it is a variable vein turbo?. (I have a TSI petrol so I don't know the specifics of your setup). Is the actuator vacuum or electric? Look for vacuum leak or loose/cruddy electric connections dependent on the circuit. Third guess is a loose clamp on your intercooler hoses, either pre or post intercooler. Here though I would expect you to hear leaking air as part of the symptoms.

There, that should give you something to think about!

Hi and thanks for your help, there's certainly plenty to get on with there.

Much appreciated

KIeran