One for the car mechanics

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  • One for the car mechanics
  • fivespot
    Member

    Broken cam belt 😯

    hexhamstu
    Member

    would probably spark once before the ECU faults on the non-turning crank (or so it senses).

    simon430
    Member

    Plugs should spark, but maybe not in the correct firing order with a faulty crank sensor. I would be checkibg the cambelt too.

    Rockhopper
    Member

    Engine will turn over but not start. You wouldn’t get a spark as the ECU doesn’t know where the crank shaft is to tell the coil packs to make the plugs spark at the right time.
    Crank sensors either work or they don’t, they often fail when they get hot then start working again as they cool down. It’ll throw up an error code so its worth getting them read before you go to far.

    Premier Icon molgrips
    Subscriber

    You need VCDS that’s what you need.

    wysiwyg
    Member

    Would a faulty crank position sensor still have an engine sparking.

    My a4 cranks, plugs are wet with fuel and it sparks against engine case.

    Common faults seem to be cps or temp sensor. But someone’s said faulty cps would mean 0 spark so trying to narrow it down

    wysiwyg
    Member

    Codes read nothing bar the one that said I’d pulled the battery. Cambelt is fine. We have fuel we have spark. We have no bang.

    Premier Icon michaelbowden
    Subscriber

    Have you filled up recently??? Are you sure you put petrol in??
    If CPS has failed you are very unlikely to get a spark or fuel. I dont know VAG systems very well. Does the revcounter normally register when cranking? Is it now?

    You could be flooding the engine if it thinks it is feezing cold and over fueling. Is it definately petrol on the plugs??? Remove all the plugs, burn them dry in the gas hob or something.
    Remove fuel pump fuse and spin the engine over with the plus removed, are you getting much fuel out of the plug holes?? Leave for 15 mins or so to allow excess fuel to evaporate.
    Refit plugs (don’t refit fuel pump fuse) crank over. Does it cough/try to start?? Recheck plugs – are they stil dry? If yes refit again, refit fuse and crank for a normal starting period, if it doesn’t even want to try to start check plugs again. If they are wet again then you are massively over fuelling, poss temp sensor.

    If you have spark at the right time and and fuel of the right type/quantity then you have a mechanical problem. Are you sure the belt hasn’t jumped a tooth or two giving poor compression?

    Premier Icon molgrips
    Subscriber

    We have fuel we have spark. We have no bang.

    Do you have air, then?

    wysiwyg
    Member

    I only drove 10m last time so the word on the street is flooded?

    Gonna give the above a whirl and it’s due new plugs so I’ll grab some. Cheers

    wysiwyg
    Member

    Pulled all the plugs. The top of 2 pistons look damp. Pulled the fuel line off the rail turned it over and fuel went about 5′. So not fuel pump.

    I’m letting it dry out ATM. Just in case with no plugs

    Premier Icon michaelbowden
    Subscriber

    Fingers crossed you just flooded it

    wysiwyg
    Member

    Newp. Heads being scratched now.

    With it being jumped and pumping pedal can nearly get it to start. It almost wants to go.

    markyboy
    Member

    Sounds flooded.can be a nightmare to get going.remove plugs and fuel pump fuse crank over with plugs out to clear cylinders.clean plugs refit crank again with fuse still out should fire and die.then put fuse back in and try.also possible timing belt jumped a tooth.is it just a non start or did it cut out?

    wysiwyg
    Member

    Just a none start. Tries to start.

    Ive deffo got fuel as far as the rail. Past that im unsure..the plugs were wet before..

    triop
    Member

    Remove the crank sensor and check that the end doesn’t have metal debris
    from the ring gear stuck to it (the end is magnetic), although CPS sounds about right. Sometimes if the engine don’t fire up there is no codes to read.

    Premier Icon michaelbowden
    Subscriber

    So are the plugs not getting wet now? After you’ve been cranking does it smell petroley (not a real word) from the exhaust? Have you checked cam timing or just assuming it’s OK?

    Does this mangement system have a cam position sensor as well as a CPS? If it does and you have no faults I would assume the belt hasn’t jumped at all.

    triop
    Member

    edit from previous post, assuming CPS = cam sensor

    Premier Icon michaelbowden
    Subscriber

    Ah, CPS for me was always crank position sensor!

    wysiwyg
    Member

    Havent pulled the plugs again.

    It has a cam and crank sensor i believe.

    The obd vag reader ive got im not sure if it will pull all codes.

    Mate says I can use him to get the AA out. Will they have a proper reader?

    Premier Icon michaelbowden
    Subscriber

    Your reader should pull everything you need. The Aa will have something more complicated but will probably just give more detail.

    If it has cam and crank it should pick up if the timing belt has moved, so hopefully you’re OK on that front.

    wysiwyg
    Member

    The sweet sound of success.

    Think it was flooded but in prattling around hadn’t put fuel relay firmly in.

    Premier Icon michaelbowden
    Subscriber
Viewing 23 posts - 1 through 23 (of 23 total)

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