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  • VW Polo – misfiring?
  • zyxw
    Free Member

    I’m looking for a bit of advice re a misfiring VW Polo (I read the forum occasionally and have seen similar posts so thought I’d post myself and see if anyone could help)…

    The car is a 2003 1.4 TDI PD 75 (3 cylinders) and currently seems to misfire/start on only 2 cylinders. After a few miles and after stopping for a few minutes the car always starts perfectly and runs normally again. Once running normally the underlying problem sometimes surfaces (but is barely noticeable) when the car is idling at lights. The same pattern repeats if the car is parked for a few hours. Car was last serviced in December. Mileage 130k.

    I’m just in the earliest stages of looking into this problem and I suppose I’m looking for suggestions as to what the problem might be/worst case scenario repair costs (if anyone has experienced something similar).

    Thanks in advance for any help.

    trail_rat
    Free Member

    My van did this , it was a dead glow plug.

    It was coupled with black smoke till it warmed up and ran on all 4 though.

    It also sound like crazy diesel hammer.

    zyxw
    Free Member

    Thanks for the reply.

    The glow plugs were replaced about a year ago when the engine was more often than not failing to start but I suppose they could have gone again. I’ve now read up on the glow plugs/misfire link and will look into this further.

    Thanks again.

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    mrmo
    Free Member

    what state is the battery in? just wondering if it struggling to provide sufficient kick?

    thekingisdead
    Free Member

    The mis-firing at idle once the engine was running would rule out a battery / glow plug issue I’d have thought ?
    Once it’s running a diesel should run on their own without glow / plug or battery?

    trail_rat
    Free Member

    Modern diesel glow plugs dont just work at start up. Anymore

    They can be on for up to 5 minutes after till cylinders get to temp.

    zyxw
    Free Member

    The misfire at idle once the car is running properly is very, very slight and doesn’t always happen.

    I did have a flat battery a couple of months ago having not used the car for a while – the breakdown guy at the time said my battery was fine and didn’t need replacing.

    The car went into limp home mode once a few months back and I remember noticing the first signs of the engine idle problem then. The lack of power at the time it went into limp home is very similar to the lack of power I’m currently getting on first start-up i.e. I have to put my foot right down in first gear to move off from lights in the first few minutes of driving. I’m guessing this lack of power is because the car isn’t running on all cylinders.

    For info, my garage couldn’t replicate the fault when it first surfaced and to be honest don’t seem to be specialist enough for me to spend money on an attempted diagnosis. I have also posted this on a VW forum so might get some additional suggestions there. I’ll post any outcome here in due course in case it helps someone else.

    Thanks again for the suggestions. It’s an old car but I’m kind of desperate to keep it on the road!

    andydicko
    Free Member

    Sticking valve, common on VW 3 cyl engines!

    zyxw
    Free Member

    I think I read something somewhere about sticking valves. That would stop fuel getting through, a lack of power/juddering on first start up wouldn’t it? If it turns out to be a sticking valve, any idea how much fixing the problem would cost? I’m guessing it would only be one valve (in the misfiring cylinder) that needs fixing/replacing?

    bikemike1968
    Free Member

    The valves themselves are only a few quid, it is paying the mechanic to strip down the top of the engine that costs, it is several hours work. Add on the cost of gaskets, new oil and coolant etc and you are looking at a big old bi?l I’m afraid.

    zyxw
    Free Member

    Thanks for the information. If it turns outs to be a valve issue (and not a glow plug one) and my garage can fix the problem they aren’t bad for labour costs. Approx. £35/40 per hour if I remember correctly. Which I suppose then brings me to gaskets etc. Any ideas how much those bits and pieces would add into the equation?

    chickenman
    Full Member

    Injector wiring was a problem on PD engines, VW chose to use ordinary rather than heat resistant cabling for the injector loom.
    Your symptoms sound like a problem I had on my Passat. Bought an OBDII (?) fault code reader on ebay, googled the vw fault code and it came up with “no1 cylinder injector wiring fault”).
    New loom was £45 fitted by myself; problem solved.

    molgrips
    Free Member

    Once running normally the underlying problem sometimes surfaces (but is barely noticeable) when the car is idling at lights.

    NOT glow plugs then.

    Injector wiring is a possibility.

    zyxw
    Free Member

    Thanks both. I can’t fix it myself (so probably no point in buying a code reader) but it’d be brilliant if it turned out to be an injector wiring fault. I don’t want to pay VW prices for diagnosis so will phone around for the next best option. I’ll update this thread once I know for sure what the problem is.

    chickenman
    Full Member

    Code reader was £25 and you can google away at your leisure. A mechanic on £45/hour doesn’t have that luxury and will go with gut instinct if his software doesn’t immediately throw up the right answer. A Bosch auto electrician specializing in VAG cars will have heard of the injector wiring problem; not cheap though.

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