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Fixed my HID light now wont start! help!

Discussion in 'A4/S4 forum(B5 Chassis)' started by androo700, Nov 30, 2009.

  1. androo700
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    androo700 New Member

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    So, here's the saga:
    My A4 1999 Quattro driver's headlight failed about a fortnight ago. Initially I thought it was the bulb so bought a new one (at £60+VAT!). Took it to Audi as I didnt' want to touch the thing, they fitted it and said it wasn't that; they didn't charge though, which I was impressed by.

    So, took it home and this weekend had a good old fiddle... but fixed it.
    I removed the headlight to get the bulb out. The connector to the bulb had a black mark, like something had blown. I scrubbed it clean with a wirebrush and put the bulb back in. NB: I did, inadvertantly at this point try the headlights (with ignition on) and heard a funny buzzing/rapid clicking noise from the engine compartment.
    Put all back together and headlights worked! Great!

    Now, any sensible person would've quit whilst ahead. Not me ... I was on a roll, and was next going to fix my ongoing ABS problem. I checked every fuse, to no avail. I also removed the ABS controller connector, and refitted.

    The following morning I went to start it and it just turned and turned but wouldn't fire. 2 days later, still won't start.

    I've done the following:
    - checked errors with VAGCOM. Showing 17833 evap purge valve n80 short to ground. Also showing water coolant sensor intermittant (this has been like this for months). Also I initially got MAF errors, but these have now gone, and I put them down to me driving it without the air intakes fitted for the fortnight.
    - I've checked all the fuses in the side panel.
    - I've checked the fuses behind the bolted drivers panel near the relays.
    - I've taken out the headlight and re-fitted.
    - I've removed the connector and tried headlights again (still buzzes/rapidly clicks ... so not sure if that's a sign that whatever relay it is is still ok?).
    - Fully charged battery. Engine turns perfectly freely.
    - Checked for fuel pump prime - sounds fine... not sure how else to check.

    Not sure what to try next. Would the VAGCOM tell me if it was a spark plug problem?

    One funny thing, if I remove the fuel pump fuse then try starting (with the fuse out) I get a short fire... this is the only way I can get it to fire.

    I suppose the EVAP purge valve is the first thing to test as it's the only consistent and new fault. Any ideas how I start with this?

    Thanks
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    What exactly is buzzing?

    You had the air intake out? The coil drivers for the sparks are mounted on top of the airbox, so might be worth ensureing they're connected up properly.

    If you have vagcom, you should be able to wind the engine over and see if the ECU can see the motor cranking using measuring blocks.
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  3. androo700
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    androo700 New Member

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    Hmm, not sure what's buzzing. I'll try and find out, but it could well be the door-open warning that just isn't working properly because the circuit isn't complete.

    I don't mean the full air intake - just the plastic that goes from above the radiator and into the air filter, and the plastic cover ontop of that. I see a couple of connectors there, one which looks like the mass air flow sensor and both seem connected fine.

    I can use vagcom to view the engine turning and monitor air flow, compression and so on. Is this what you meant?
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Correct.

    So if its not starting, you need to ascertain if the ECU is trying to start the motor but cant, or isnt trying at all.

    If you look at the measuring block for engine rpm and wind it over, it should register a few hundered RPM on the starter. If so you can assume the ecu is trying to start the car, but cant. It would also be worth checking for fuel. If you have fuel but no spark, that points to a coil pack or coil driver issue. What engine do you have?

    If the measuring block shows nothing, then it would perhaps point to a crank sensor failure.
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  5. androo700
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    androo700 New Member

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    Thanks for the advice. I'll try what you suggest this afternoon when I get home. I have the 2.8v6 engine.

    The other thing is that I have the non-registered version of vagcom, so lots of features are disabled by default. I'll try checking for engine RPM though and post back later.
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  6. androo700
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    androo700 New Member

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    Ok, home now. Just run a test at starting with vagcom logging. Here's the result. (NB. reads better if you open with Excel, as opposed to using a non-Microsoft browser like FireFox which decides to open in the browser)

    Anything look strange there?

    Thanks,
    Last edited: Dec 1, 2009
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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Well looking at the log the engine appears to be doing a consistant 120rpm (perhaps too consistant?) and the maf figures are probably about right too.

    Are your plugs wet with fuel?

    Are you getting a spark?

    Does the fuel pump run while cranking?
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  8. androo700
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    androo700 New Member

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    OK, just managed to get the wife to nip out to help me test for a spark.

    The plug I tested smelled of petrol, and sparked fine when engine turned.

    How do I know if the fuel pump is running while cranking?
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  9. jcb
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    jcb Active Member

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    If you really want to know you can unplug injectors and put them all in coke bottles.
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Just have a listen near the tank. Theres a hatch you can open in the boot floor to access the top of the pump. It should emit an audiable whirr when cranking and possibly when you first turn the ignition on.

    You have a spark, so its only fair to assume the problem is fuel related?

    Might also want to check the fuses in the fuse box for the pump etc?
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  11. androo700
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    androo700 New Member

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    Hmm, no sound coming from the pump (even took the cover off).
    Also no voltage across the connector going to the pump.
    ... Also, no voltage across the pins for fuse 28 - Fuel Pump! Neither on ignition nor whilst turning over.

    Hmm, what would cause that? Key battery was one thought I had (though I've tried two keys)... I'll change the battery in the spare key and re-pair it.
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  12. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    nowt to do with the battery

    The immo is passive.

    I'll dig the wiring out in a moment and see if the fuse is after the relay.
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  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Seems like thats the case.

    Relay is unfused from the main bus, and then the output of the relays terminals runs to two fuses, one for the injectors and one for the fuel pump.

    If the fuse isnt live, the relay isnt closing.

    Seen as you have a spark, i would imagine the relay is dead, or theres some kinda wiring fault.

    You could try bridging the relays terminals with a suitable wire jumper and see if it starts?
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  14. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Incase your unsure, you'd need to connect pin 30 of the relay to pins 87F and 87a.

    You'll probably be greeted with some sparks and a whirr from the pump. If so, try to start it.
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  15. androo700
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    androo700 New Member

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    Mmm, sounds plausible.
    I don't have a manual, can you tell me the relay number?
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  16. androo700
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    androo700 New Member

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    ... also checked some of the other neighbouring fuses... stereo is live, rear heater is live, engine control unit is dead! Or would it be until it starts?

    Or is the circuit fried...
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  17. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    i dont think there is an "engine control unit" fuse.

    Its probably the other fuse i mentioned above, for the injectors. Both get power from the fuel relay

    The ECU defo has power, as you've been chatting to it with vagcom and its sparking...

    Its relay 4 according to etka for a '99 2.8 30v
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  18. androo700
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    androo700 New Member

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    Just got home and bridged the relay contacts (relay 4 has a diagram on the bottom with T, 30, 86, 87 and 87a).
    I bridged 30, 87 and 87a with ignition on and whilst turning, nothing, no sparks and no whir from the pump.

    I put the relay back in and tried again and with a friend's help there is a whir from the pump... and I hear clicking from the relay at the same time.
    Nothing happens on just ignition though - only when the engine is turning.

    Hmm, what next?
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  19. androo700
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    androo700 New Member

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    Just taken the relay into the house and tested across the switched outputs and it clicks and changes voltage... so I'm guessing the relay is fine.
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  20. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    hmm, put a test meter onto terminal 30 and see if you've got battery voltage at it?

    The pump should have run when you bridged the contacts...

    30 is permenant live, and 87 is the pump...

    Bridge the contacts again, and check for 12v at the green/yellow wire at the fuel injectors. If its there, and theres no whirr, the pump is suspect.

    With the relay fitted, check for 12v at the injectors (as above) and at the pump (same color, green/yellow) while cranking.
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  21. androo700
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    androo700 New Member

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    Called RAC out in the end. He started it by using his battery pack and jump leads after 30sec of turning.
    Reckons it was undoubtedly flooded.

    Rather puzzling... but I'll see how it goes today and post back if I experience more problems.
    Otherwise, thanks Aragorn for all your help.
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  22. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Very odd.

    Wonder how it became flooded in the first place?

    Do you touch the throttle at all while trying to start it?
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  23. androo700
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    androo700 New Member

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    It is odd, but it's been running fine since.
    I always start it with throttle half depressed since if I don't it just stalls as soon as it's started (don't even have time to boot throttle after starting). This normally works perfectly, but obviously didn't on that one day.
    I wonder if I had a fuse dislodged or something that stopped it starting, and although I sorted it, it was too flooded to start?

    Anyway, lessons learned... I think :|
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  24. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Hmm, sounds like you flooded it then.

    You shouldnt need to touch the throttle at all. If it stalls theres something wrong with it...
    #24

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