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Agu Non-start Help

Discussion in 'A3/S3 Forum (8L Chassis)' started by novril, Aug 26, 2014.

  1. novril
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    novril Member

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    [Aug 26, 2014]
    Hi all,

    Getting a tad desperate on my mk4 Golf now, I'll copy the post I made on ukmkiv's and would really appreciate any help as I am running out of things to test now!

    *
    I swapped my turbo back over ko3s back to the ko3 it originally had. Now it turns over but won't fire. No faults in vcds, check the plugs and they are wet with fuel. Getting a very slight spark when I tried with the plug removed on the coil.

    I have looked everywhere for a plug I may have left undone, but it looks okay. Even did a compression test which was just over 200 psi on all 4. 14bar.

    What are the symptoms of a faulty ignition amp? It tried to fire once or twice initially. But now it's not even trying. I think it's the amp so want to try another really. I have tried another Ecu and taught in the immobiliser (swapped over from a mapped ecu).

    If it is an ignition amp are they main dealer only? I'd better spend some pennies unless anyone is near Salisbury who would let me borrow one for an hour?

    Cheers,

    Mark.*

    *
    Right a little update.



    I have checked all fuses and fuse links on the battery. All okay, I get a very strong smell of fuel when cranking. Removed the plugs and attached to the coils and turned over with injectors unplugged, a nice bright spark on all four plugs. Checked the engine is drawing air, sucking on intake pipe when cranked.



    Fuel pump checked, fuel pump only runs for about a second when the ignition is switched on, this spurts out around 100~150ml of fuel and then stops. I have run a 12v feed to fuse 28 which runs the fuel pump all the time, fault is still the same. I remove the plugs and dry then off before cranking over. The fuel pipes are now firm with pressure.



    I am running out of things to check now, how can I test the ingnition amp? Would I be able to see a difference between a weak spark and a normal one? Everything I have read suggests an ignition amp fault leads to a missfire.



    Can anyone think of anything I could have inadvertantly knocked, unplugged or caught some wires during the turbo swap?



    Engine doesn't run with a number of sensors unplugged one at a time. MAF, coolant temp sensor, lambda sensor.



    I could do with a few things to check if anyone has any ideas?



    VCDS returned no fault codes when I scanned it before, I will plug it in again to try and monitor some actual values to see if it gives me any clues.



    Thanks again,

    Mark*

    So if anyone can offer any help I would really appreciate it. I am a Merc truck/van mechanic so know my way around a vehicle just not completely clued up on a petrol engine and this one is doing my head it!

    Thanks all.
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  3. Mrharris2
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    Mrharris2 Member

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    [Aug 26, 2014]
    Hi not sure if it's of any help but had this happen to me first was my ignition amplifier cost me £20 fixed it a treat then my fuel pump relay went its under the dash 6 hex bolts in under the cover behind the door and 4 under the steering wheel. Not sure of the part number now but I had the same issue both times and fixed it a treat...
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  4. novril
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    novril Member

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    [Aug 26, 2014]
    So your ignition amp stopped it starting? Everything I have read about them says it's misfire only. I don't have another one to test with unfortunately. Did you check for a spark or just replace it?

    I have bypassed the fuel really and powered the pump and it still won't start.

    Thanks for the input.
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  5. Mrharris2
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    Mrharris2 Member

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    [Aug 26, 2014]
    Hmm you've got me now as it was last year it started with a misfire then I'm sure it wouldn't start I just replaced it as it was £20
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  6. basil brush
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    basil brush Active Member

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    [Aug 26, 2014]
    ive had exactly the same thing :)
    unplug all 4 injectors then try to start it !
    it will throw up 4 codes relating to the injectors being unplugged but can be cleared .
    i tried ignition amps , plugs , coils even bought a new set of injectors and a loom for them and it was a new faulty ECT sensor !!!!!!!!!
    gauge read fine but was telling the ECU the engine was the wrong temp acording to the maf readings confusing the hell out of it so it hosed fuel in flooding it !!!!
    unplugging the injectors stopped any additional fuel being added and what was in the bores burnt off and cleaned the plugs up :)
    try it

    baz
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  7. novril
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    novril Member

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    [Aug 27, 2014]
    ECT sensor? Coolant temp sensor? It's a fairly new genuine one, only not starting since I have had the turbo off! I'll give it a go!
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  8. basil brush
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    basil brush Active Member

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    [Aug 27, 2014]
    Mine was a brand new genuine one ! It's as likely to give up just like that as an ingnition amp could !
    For the sake of 4 little plugs it could be worth a try !
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  9. novril
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    novril Member

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    [Aug 27, 2014]
    Yeah I'll give it a go mate. I've turned it over lots to try and dry out. Even tried with temp sensor unplugged but still wouldn't start.
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  10. basil brush
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    basil brush Active Member

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    [Aug 27, 2014]
    An unusually helpful AA man showed me that trick !
    I called them out 4 times to the same fault over the space of a month , the first 3 weren't interested and just wanted to tow me somewhere but the 4th guy couldn't do enough to help me :) man1 being the worst as he refused to even plug it in stating "nah geeze it's to old " still his incompetence got me a huge discount on my next years membership :D
    Your getting fuel and a spark so it's either not enough of a spark , a spark at the wrong time or incorrect amount or badly timed fuel !
    Have you disturbed the crank or cam sensor ?
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  11. novril
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    novril Member

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    [Aug 27, 2014]
    Not intentionally. Rev counter moved and vcds logs engine speed.

    Going to check crank sensor later, where is it on this engine? Didn't notice it when looking before. Thanks again for the heads up.
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  12. basil brush
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    basil brush Active Member

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    [Aug 27, 2014]
    Cam sensor is just above the cam belt on the end of the head , you can just see the multi plug sticking out from under the corner of the engine cover , the crank sensor enters the block just above and to the right on the front of the block , plug is a grey one which clips up onto the inlet manifold , bit of a fiddle but manageable :D
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  13. novril
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    novril Member

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    [Aug 27, 2014]
    Perfect, thanks mate. I'll have a look at these later. Is it best to unplug the temp sensor or will it default to over fueling anyway?
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  14. Prawn
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    Prawn My other car is a MINI!!!!

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    [Aug 27, 2014]
    Not trying to fire or run at all is an unsual one. It'll usually attempt to run in a fashion even with lots unplugged.

    I'd be checking the crank sensor plug at the front of the engine under the inlet mani incase you've knocked the plug or something similar. Without the crank sensor you won't get anything at all. Although you'd usually not get a spark either.

    It could be worth tracing the loom back to see if you've mistakenly pulled too hard on any wire / plug also.

    Aside from the turbo, what else have you had off / changed since it last ran?
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  15. novril
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    novril Member

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    [Aug 27, 2014]
    I've changed the turbo, put the cat back on and swapped complete exhaust over. Swapped the Ecu over (neither would start it, coded the immo) the lambda sensor is the same one just swapped between exhausts. Also the TIP but everything is connected to it.
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  16. novril
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    novril Member

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    [Aug 27, 2014]
    I've been lying on the top of the engine and had my arms around the top of the gearbox but can't see anything I may have knocked/broken. I'll investigate the crank sensor.
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  17. novril
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    novril Member

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    [Aug 27, 2014]
    Under the inlet manifold I can only find a knock sensor to the rear of the black near the bell housing? Does the crank sensor read off the flywheel?
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  18. novril
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    novril Member

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    [Aug 27, 2014]
    Aha! She lives on!

    Rechecked the spark today. Seems that 2 were now not sparking. (they spark even if they aren't grounded to the rocker cover) moved plugs around and the lack of spark followed.

    Popped down to the factors and 16 quid later got a new set of plugs and she fired up!

    I had genuine bosch ones previously with single tip, new ones are ngk and have 3 tips, is this just another type of plug?

    Thanks again for all of the help, very much appreciated!
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  19. Mrharris2
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    Mrharris2 Member

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    [Aug 31, 2014]
    I have the NGK ones they work good for me some people use the bkre ones glad it's sorted
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