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Minor mods = rubbish idle

Discussion in 'A3/S3 Forum (8L Chassis)' started by AG205, Jul 22, 2012.

  1. AG205
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    AG205 Member

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    [Jul 22, 2012]
    Put a post up the other week about having idle problems following fitting a Badger 5 TIP and a few other bits. Once it was all back together it was giving me a rough low idle probably from an air leak and after hunting about I found three cracked plastic hoses and a hole in the rubber junction jobby that attaches to the end vaccuum outlet on the inlet manifold.

    So rather than splashing out on VCDS (mistake?) to check for fault codes etc I decided to delete the spaghetti of vacuum tubing both under the inlet manifold and on the cam cover and fit a catch tank.

    This was the result:

    [​IMG]

    [​IMG]
    Didn't really have space to fit the catch tank in the bulkhead area and as I made an extra battery clamp a while back I decided to just weld a little bracket onto that to mount the tank to.

    [​IMG]
    New catch tank pipe connects directly to the crankcase breather outlet and deletes the standard PCV (which was also looking ropey). I also bunged up the larger vacuum port underneath the middle of the inlet manifold.

    [​IMG]
    Also decided to vent to atmosphere since the hockey puck valve was full of oily crud and a new one from Audi was £30+VAT. So I just ran a hose to the discharge underneath the car.

    [​IMG]
    Fitted a new pipe from the servo as this was cracked at the bulkhead connection. Added an alloy one way valve also to replace the standard plastic one.

    [​IMG]
    Was also fed up with nearly snapping the dipstick tube (especially as I have just bought a new one) everytime I wanted to take the bracket that sits in front of the inlet manifold off. So I made a little removeable guide so I can just unbolt that instead which should simplify matters.

    Have so far just hidden the N249 valve for the time being until I get round to making a proper bracket for it. Also the clear PVC hose may look lovely at the moment but will probably only be clear for about 5 minutes before it turns yellowy-brown so I'll be on the lookout for something opaque and more flexible if I can find it.

    Anyway, after all that lot, I started the car hoping that everything would be solved and I'd avoided buying VCDS (and a laptop) for the time being...........but no, still idles like a pile of sh*t. It has changed though as now it idles high and sounds like it's misfiring.

    Any help would be great as it's been off the road for a while now and I want to drive it!!

    [​IMG]
    I might have to resort to getting the other car Mot'd to use in the meantime!
    Last edited: Jul 22, 2012
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  3. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Jul 22, 2012]
    Have you got a boost gauge fitted? How does the car drive under boost etc?
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  4. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Jul 22, 2012]
    Also have you tried unplugging the maf and runningthe car to see how it runs?
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  5. AG205
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    AG205 Member

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    [Jul 22, 2012]
    To be honest I haven't driven it as the idle sounded pretty dodgy and didn't want to do any damage if it's running lean.

    I did try it with the MAF unplugged and it didn't make any difference. I did have a go at cleaning the MAF before I put it all back together. I also changed took the inlet manifold off to get to the vacuum/breather pipes and replaced the manifold gasket, injector seals and seats (with added sealant to make sure).

    Thing is, I've now tinkered with that many things, the list of possibilities for leaks etc is pretty long!!

    No boost gauge by the way.....
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  6. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Jul 22, 2012]
    Shame your a bit away from me, im only in south yorkshire so id have scanned the car for you. Other thing is to buy a cheap vcds canle of ebay, you scan at least scan the car to gather some idea of whata wrong.
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  7. AG205
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    AG205 Member

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    [Jul 22, 2012]
    Suppose that would be the idea thing if there was someone nearby who could check it out with VCDS....
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  8. antwan
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    [Jul 22, 2012]
    Did the problem start after fitting the TIP ? if so, just re-trace the installation, something is either split/ kinked or simply just not fitting correctly, its a frustrating problem, but it sounds like an air leak, patience needed.....
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  9. AG205
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    AG205 Member

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    [Jul 22, 2012]
    Yeah I'll have to buy some carb cleaner and start squirting it about the place to try and locate it.

    One thing is though that when I unplugged the MAF it made no difference, is that right?
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  10. bowen
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    bowen Member

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    [Jul 26, 2012]
    is this happening first thing in the morning/cold start? or just all the time when idling?
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  11. AG205
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    AG205 Member

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    [Jul 30, 2012]
    I haven't driven since this has been happening as it sounds so bad I don't want to do any damage but it happens constantly at idle.

    I've now replaced the spark plugs, cleaned the MAF, throttle butterfly & IAT sensor and sprayed WD40 around the injector seats & seals but nothing has changed. Also fault code read it but it's only bringing up P0420 which is to do with the cat not being efficient enough which I assume is to do with using Hi-Flow cats. I was expecting a misfire code but nothing came up.

    Now getting VCDS to see if I can spot any problems.
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  12. AG205
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    AG205 Member

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    [Aug 24, 2012]
    After a couple of weeks of pratting about and a new MAF sensor I've found the cause of the problem..........1x dead injector causing a lean misfire and making the engine vibrate on it's mounts. My fuel economy had been getting pretty bad recently so think that must have been the culprit.

    Good old Audi were asking £140 each for a replacement injector! Luckily a mate has an Andrew Page account so knocked off a fair bit to get one for £60 in the end (would normally be £89). Competitive pricing by Audi there!
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  13. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    [Aug 24, 2012]
    Glad its sorted mate, while your at it id use a ultra sonic clean and do the other 3 and also replace the injector seals as they can cause a vacuum leak if worn.
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  14. AG205
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    AG205 Member

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    [Sep 3, 2012]
    Yeah I got the other 3 cleaned and got new seals installed. Fitted new injector seats a while back too but used some dodgy sealant on them and they started leaking a bit so took them out again and sealed them with mucho threadlock this time and hopefully they'll stay leak free this time!

    Also found yet another crack plastic vacuum pipe contributing to the sh*t idle - the pipe from the servo that runs behind the heatshielding on the bulkhead.........if you are having air leak problems from the pipes underneath the inlet manifold definitely check that one too as mine had nearly fallen off the connection was so cracked!
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