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  • Car trouble – any suggestions? (Passat diesel)
  • Mowgli
    Free Member

    Car went a bit funny yesterday but seems ok now. Just wondering if I should forget about it or get it seen to. 2008 Passat 1.9TDi.

    I started it up yesterday and about 2 mins in to the journey I turned onto a fast steep hill, so floored it and pushed it pretty hard to get up to speed – nothing outrageous, probably not much above 3000rpm, but foot to the floor up from 1st, 2nd, 3rd 4th. About 5 secs into this hill, it suddenly lost power and I had to change all the way down to 2nd to crawl to the top of the hill. Had a look under the lid and couldn’t see or hear anything obvious. Left the engine running and limped home as I was worried it wouldn’t start again. The rest of the journey it drove like it had a 900cc Yaris engine and was towing a caravan. No power at all.

    Got home, switched off, then a little while later started up and went for a spin, and it was absolutely fine.

    So what was it?! The tank was on about 1/8 so fairly empty. I wondered if that, plus going up a steep hill had sloshed the sludge in the tank onto the fuel filter and perhaps restricted fuel flow? Turning off the engine might have let said sludge drop back into the tank. I don’t know anything about how this fuel system works so not sure if this is likely. I had thought the turbo might have died, but it now works again, so could the turbo have suffered some temporary fault? Something clogging a tube perhaps, which turning off might have cleared? There were no warning lights on the dash, and strangely the reported fuel economy was slightly above what I’d have expected (which makes me think it could be turbo-related).

    I wondered if it’d be worth getting the fuel tank cleaned out and filters replaced? I’d rather not just go to a garage and give them a blank cheque to ‘find out what’s wrong’ as it could take ages to check all the different possibilities, and might not find anything at all.

    Cheers!

    nickdavies
    Full Member

    Some fault has caused the car to go into limp home mode, that’s so you can get back hopefully without causing further damage. Then when you restart the car it will work normally unless the fault repeats.

    Get a VAG specialist to plug it in and take a look.

    saxabar
    Free Member

    I know nothing about cars, but I think this is a known problem with VWs. I have a Touran that does the same. Definitely not the fuel tank though. I’ve gotten into the habit of turning the ignition off and on while moving. Not a perfect solution I admit!

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    Sundayjumper
    Full Member

    Even though there was no warning light, the car has (probably) recorded some info as to why it went into limp mode. Unlikely that it’ll pinpoint the problem but an experienced VAG specialist should be able to make an informed diagnosis.

    FWIW, totally different problem, but when my car broke down last year the RAC bloke plugged his computer in and declared the crank sensor to be dead. It was actually the fuel pump. So not every expert is an expert…

    jam-bo
    Full Member

    Our Passat used to do that if you booted it from cold. Solution was to let it warm up before booting it.

    rudebwoy
    Free Member

    ours does that –turbo issue ?

    Mowgli
    Free Member

    Thanks for the suggestions. I do hope it’s not the turbo! It is unusual to floor it from cold so will try to avoid that in future. Will see if the local guys can diagnose it with their machine…

    wysiwyg
    Free Member

    Stuck EGR or turbo problem is where my money goes

    wwpaddler
    Free Member

    We have a 03 passat with the same engine which did a similar thing but quite intermittently. Garage gave us a fault code which according to the net is fairly common and is a faulty switch on the turbo. Garage also mentioned it might be the turbo vanes sticking.

    We bunged some injector cleaner in with a tank of fuel – never done it since.

    I don’t know enough about cars to explain this but it worked for us and is a lot cheaper than turbo repairs.
    Could all be coincidence though.

    codybrennan
    Free Member

    This was going uphill? So, fuel is draining back to the tank.

    My money is either on:

    a)the in-tank lift pump (if fitted). With age they become less effective until they fail completely, sometimes just because they’re silted up. Going up a steep hill means the tank is lower with respect to the tandem pump than it normally is, and the lift-pump can struggle

    b)an air-leak in the inlet side. Check all of your fuel lines for good connections, look for diesel leaks, is the full filter in good condition?

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