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Spark plugs??

Discussion in 'A3/S3 Forum (8L Chassis)' started by Davsurfa, Sep 19, 2009.

  1. Davsurfa
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    Davsurfa Member

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    [Sep 19, 2009]
    I've noticed my car is getting more and more difficult to start in the mornings or whenever the engine is cold. I'd turn the key and when it finally starts it'd run on 3 cylinders but by the time I get to the end of my road it's running sweet as a nut on all 4. So the first port of call was to check the plugs, figured I'd start with the easiest ones to get to. I pulled the plug on cylinder 1, it's looks ok, the gap is a little smallish but not wildly out. Gapped and cleaned it went back in. Pulled cylinder 4 plug, colour-wise the insulation was quite brown and the ceramic around the center electrode was cracked in three places and rattling around on it's own. Easy fix, just bang a new plug in, job done.
    Took a stroll into town to find a replacement plug only to find no-one in Daventry stock Bosch spark plugs!! NGK only!! Hmmmmm.... I don't particularly fancy removing the black manifold and what looks like the injector bank just to swap two plugs. I bought a NGK plug that for some reason has 3 side electrodes whereas the Bosch ones only have 2. Anyways, I put it in and it has solved the starting problem.

    Now the reason for this thread, the fella in the shop reckons you shouldn't mix NGK and Bosch plugs. Apparently due to "spark plug technology" they work differently. Now is he just trying to get me to buy more plugs or is he right?? In my mind the plug just causes the spark.


    By the way, the car is running sweet as a nut at the mo with mixed plugs.
    Last edited: Sep 19, 2009
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  3. h100vw
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    h100vw Member

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    [Sep 20, 2009]
    Personally I think you're being tight not fitting 4 plugs. If one has a cracked insulator, chances are it has been overheated and the same is likely to have happened to the others.

    Your choice but they last for ages so a new set is going to be in there for a long while.

    Gavin
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  4. Davsurfa
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    Davsurfa Member

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    [Sep 20, 2009]
    Gavin, I take it by your inadequate reply you have no idea how to answer the question. However, in reply, it's not a case of being "tight". I'm sure I could afford the extra expense of £12, it's more the fact I do not wish to spend the time and effort removing the black plastic manifold and what would appear to be the injector bank. Like I stated in my first post cylinder one plug was in good condition, hence the assumption that two and three were also in reasonable condition. Once the number four plug was replaced it solved the running problem.

    Now, is there anyone on this forum who is capable of replying to the question without personal slights and who actually knows what they are talking about?
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  5. fingermouse
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    fingermouse thats me

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    [Sep 20, 2009]
    I dont have a technical answer but personally I wouldn`t mix old and new spark plugs let alone different makes. I suppose different makes could draw slightly different currents and confuse the ECU but im guessing. Never seen it discussed before.
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  6. A3tell
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    A3tell Member

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    [Sep 20, 2009]
    as basic as it can get, ngk use a different core system to most other plugs, they are insulated better!
    and the 3 prong system give off a stronger spark. so if you mix the plugs with old/new and different brands, it can confuse the ecu and cause missfire when hot. so my suggestion would be to change all!!! spend the time in doing the job right.
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  7. Davsurfa
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    Davsurfa Member

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    [Sep 20, 2009]
    Sweet as, thank you for that. The job will be done.
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  8. banoffee
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    banoffee Member

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    [Sep 20, 2009]
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  9. h100vw
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    h100vw Member

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    [Sep 20, 2009]
    Sorry that my answer was inadequate for your needs. :whistle2:
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