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Help: Car won't start

Discussion in 'A4/S4 forum(B5 Chassis)' started by macca, Oct 29, 2007.

  1. macca
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    macca Member

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    Ok, this has really got me, I have ran VAG-COM but no errors, replaced battery, check i have a spark on all plugs, fuel is going in, but car just turns on starter and makes no effort to ignite.

    does anyone know if the car runs or starts, albiet rough, if you disconnect the Air flow sensor?

    I can vag-com the ecu, no errors, does this mean the ecu is ok, or should i suspect this still? are there any immobiliser issues known on the a4's?

    the car is a 98 a4 1.8T

    cheers
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  2. andybnwc
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    andybnwc Member

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    check plugs for spark and wet from fuel if wet and no spark its defo a ignition fault , immobilisers usaually start then die
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  3. andybnwc
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    andybnwc Member

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    oh and yes they run without maf pluged in but just ruff
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  4. macca
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    macca Member

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    yeah i have wet plugs and strong spark but just nothing, weird.
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  5. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Temp sensor. Thats what stopped mine from going. I changed the plugs from the Bosch super 4's and put a new temp sensor in, and she has worked well since
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  6. macca
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    macca Member

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    which temp sensor? where is it? i've checked woth vagcom and i haven't had any faults logged.
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  7. Blue_Thunder
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    Blue_Thunder Active Member

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    Was the car running fine before or have you just done some work on it?

    It does sound like an immobiliser problem. Have you just had your ECU reprogrammed? I've heard of them 'locking out' if the remapping software doesn't close down properly. It effectively crashes your ECU.

    If you've not done anything with the ECU, you're getting fuel and a spark but no bang, the only thing missing is air. There's no chance you've got a seized turbo is there? That would prevent air getting sucked into the inlet manifold.
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  8. macca
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    macca Member

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    nothing done (well apart from fitting coilovers just before hand, but not gone near electrics, apart from undoing suspension top near ecu, but car used since then), car started fine in the morning, got home from work, just wouldn't start. no problems leading up to this one either.

    i'll check turbo tonight but i'm sure that is ok. ecu is completly standard so nothing untowards there i hope.

    i have now official broken my maf while cleaning it so i need to get another one from somewhere first, damn it. they are very delicate indeed, unless that was a problem to start with (which i doubt)
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  9. Blue_Thunder
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    Blue_Thunder Active Member

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    If the car was running fine in the morning and nothing has been done to the engine I'd ignore my scaremongering!

    I know you said the spark plugs are wet, but not so long ago I had a blown fuse for my Fuel Pump. The engine turned over, but there was no ignition whatsoever. I'd check your fuses before anything else.
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  10. macca
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    macca Member

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    done that :) and the relays, fuel pump is running when starter turning over. learnt that from owning golf gti's
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  11. andybnwc
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    andybnwc Member

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    have you a spare master key ,if so try that if not swap battery in fob just to verify it aint that , and also disconnect the battery for an hour then re attach and leave the key on the ignition on setting for 25 mins then give it another try , when doing this you should hear some light buzzing from under the bonnet if not then check the fuel pump regulater and return to tank valve
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  12. macca
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    macca Member

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    spare master key i've tried, disconnected battery for 24 hours. haven't tried the ignition thing, i guess that us the throttle body allignment thing which i believe i can get vagcom to do?

    will try regulator and return valve, where is the return valve, near the fuel rail?
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