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Dodgy Idling - 1.8T

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by andylee, Nov 21, 2009.

  1. andylee
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    andylee New Member

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    [Nov 21, 2009]
    Folks, hope you can help...

    I've got some really dodgy idling problems at the moment which is getting on my nerves more than a bit.

    Basically the idle is really really lumpy, and fluctuates between 800k and 1100k.
    When running warm, the idle will suddenly start creeping up, stop being lumpy, but keep going till it reaches about 2.3k, then drop back to 800k and lumpy.

    A mate of mine has Vag-com and the error codes are listed as below.

    We also looked at the ignition timing via Vag-com, and it's steady when driving, but on idle it's all over the shop.

    I'm guessing the first thing is to swap out the temp sensor on the rad (does anyone have the part number for this?) and see what happens, as I've heard that small sensors on these cars can throw everything outa whack.

    Any other input though would be appreciated!

    Car is a 2003 1.8t Avant 163

    4 Faults Found:
    16891 - Idle Control System RPM Higher than Expected.
    P0507 - 001 - Upper Limit Exceeded
    17698 - Coolant Temp Sensor at Radiator Outlet (G83): Signal too Small
    P1290 - 002 - Lower Limit Exceeded - Intermittent
    17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
    P1297 - 001 - Upper Limit Exceeded
    17544 - Fuel Trim: Bank 1 (Add): System too Lean
    P1136 - 001 - Upper Limit Exceeded
    #1
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  3. blackpool1974
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    blackpool1974 Member VCDS Map User

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    [Nov 22, 2009]
    Hi,

    Your problem is that your crankcase breather valve is broken, this causes all the faults apart from the coolant one

    The pressure drop between turbo and throttle valve is your UFO shaped disk (pressure regulating valve) at the back of the manifold, your crankcase breather valve will of broke this £25 from Audi for new one

    Its about £20 for the crankcase breather valve, Audi usually recommend you replace the rubber pipes that is connects to as they go brittle after a few years and might break when you remove the valve

    The over revving at idle is due to the crankcase breather valve (pcv) being either blocked or broken. The lean at idle fault is due to the engine sucking in air through the valve, it should close at idle.

    try and undo your oil cap whilst the car is idling, you wont be able to, this is because of a vacuum problem caused by the valve

    It is not expensive to fix this problem (breather hoses)

    http://www.ecstuning.com/Audi-B6_A4-FWD-1.8T/Engine/Intake/
    #2
  4. andyquattro
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    andyquattro New Member

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    [Nov 28, 2009]
    Andylee have you tried any of Blackpools suggestions yet?

    I have had nearly exactly the same problem over the past few weeks on my 1.8TQ Avant, after changing my DV & MAF to no avail, I then found a blocked crankcase breather while changing my rocker cover gasket!

    While fixing it I thought it odd I could blow both ways through the pressure regulating valve, a new one is now on the cards after reading the above.

    I started of by only getting
    17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
    this alone was giving me the rough idle. It then started picking up misfires and running lean codes then more resently 16891 - Idle Control System RPM Higher than Expected.

    Fingers crossed a new PRV does the trick or its back to hunting through autotrader again!
    #3
  5. JamesSut
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    JamesSut New Member

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    [Jan 13, 2010]
    Hello all,

    I mostly have the same set of codes:
    Control Module Part Number: 8E0 909 518 AA
    Component and/or Version: 1.8L R4/5VT G 0004
    Software Coding: 0011501
    Work Shop Code: WSC 63351
    3 Faults Found:
    17544 - Fuel Trim: Bank 1 (Add): System too Lean
    P1136 - 001 - Upper Limit Exceeded
    16891 - Shareware Version. To Decode all DTCs
    P0507 - 001 - Please Register/Activate - Intermittent
    17705 - Shareware Version. To Decode all DTCs
    P1297 - 001 - Please Register/Activate

    I'm a bit confused by the description of the two valves above.

    Is the crankcase breather valve the black plastic one connected to the T pipe from the crankcase?

    I was just getting 17544 back in Dec, took it to my local VAG specialist who replaced "a valve" and pipe.
    The code came back within a few days and they then said they could do nothing with it because it needed a software update from Audi (is this code for "we don't know what's wrong with it?).

    The black plastic valve has a manufacturing date of July 09 stamped in the side so appears to be what they replaced.

    I've taken it off an looked in the side. I can see a light grey rubbery valve and a spring. The light grey bit has a split in it. Is this normal? I can't tell whether it's supposed to let a restricted amount of air through or not. Also, it's quite oily in there, is that normal? I already think I need to replace the camshaft cover gasket because a small amount of oil is running down into the spark plus wells.

    Any help much appreciated,

    James
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  6. blackpool1974
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    blackpool1974 Member VCDS Map User

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    [Jan 13, 2010]
    Hi,

    All the problems stated above are caused by the crankcase breather valve which is not easy to get to from the top If I remember rightly, I think it is to the right of the manifold near the oil filter, the valve will be hidden inside a T shaped housing that you will see if you click on the link

    http://www.ecstuning.com/Audi-B6_A4-FWD-1.8T/Engine/Intake/ES258895/

    Idling very rough at idle
    Running lean
    Pressure drop between turbo and throttle valve (broken disc shaped valve at back of the engine causes this) I went through 3 in 6 months until I fixed crankcase breather valve
    oil in plugs (due to pressure problems)
    Unable to undo the oil cap
    Last edited: Jan 13, 2010
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  7. A4 nut
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    A4 nut Member

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    [Jan 13, 2010]
    Where abouts is the crankcase breather valve i have the exactly the same problems as described and also what can be described as a fart noise every now and then from air being discharged or sucked in are there any pictures of location or of the part.
    #6
  8. blackpool1974
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    blackpool1974 Member VCDS Map User

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  9. A4 nut
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    A4 nut Member

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    [Jan 13, 2010]
    Found it no problem just got to get it done in this weather:laugh:
    #8
  10. JamesSut
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    JamesSut New Member

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    [Jan 17, 2010]
    Thanks for all the advice Blackpool1974.

    I've managed to get to the crankcase breather valve to have a look at it and get the part number (apparently the part and pipe arrangement changed during 2003). I did it by moving the coolant header tank out of the way (can just to it without disconnecting pipes, undo the screw at the front, tilt it up at the front and pull it up and forwards to get the lugs at the back out, disconnect the level sensor wire). Lean over the front grill and put one hand down the back of the engine holding a screwdriver and get the handle of the screwdriver sticking under the bulkhead towards the back of the car. Bring the other hand down the gap where the coolant header tank was to guide the tip of the screwdriver to the Jubilee clip holding the valve into the T-piece. Use both hands to turn the screwdriver. When it's loose pull the pipe attached to the valve by the smaller clip to get the valve out.

    The crankcase breather valve in mine is part number 035 103 245 G. It has what looks like a black tiddlywink inside that seems free to move around and wouldn't always cover the hole to close the valve, what's it supposed to look like? Is the tiddlywink only supposed to move in line with the hole?

    It think the disc shaped valve is the one I can see a split in the diaphragm inside and was replaced by the garage last month, so maybe I have the same problem with this one failing because the other one is leaking. In my Haynes manual it's described as a Pressure Regulating Valve and the part number of mine is 06A 129 101 D. Is this the one you meant?

    I'm going to replace both and hope my fault codes stay away, idle becomes smooth, hestitation on gentle acceleration at low revs goes away and oil stops seeping into spark plug wells. I've also had oil firing out of the dipstick (covering everything), but this hasn't happened since I replaced the dipstick (the old one had lost all of the plastic ridges that help hold it in and was very loose).

    I'll let you know how it goes,

    James
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  11. blackpool1974
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    blackpool1974 Member VCDS Map User

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    [Jan 18, 2010]
    Yes, the PRV is at the window side of the manifold, mine broke within 2 months of replacing it, told Audi and they said they had only sold 5 all year they never break on there own

    Mine sucked in oil in the plugs aswell, I assume due to the vacuum problem, my tiddlywink also had come off the spring and didnt seal correctly
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  12. JamesSut
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    JamesSut New Member

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    [Feb 27, 2010]
    Just a quick note to blackpool1974 to say thanks for your advice. I replaced the crankcase breather valve and the PRV (again) about three weeks ago and the rough idle and fault codes haven't come back since.

    James
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  13. blackpool1974
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    blackpool1974 Member VCDS Map User

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    [Feb 27, 2010]
    Pleased for you, cost me over £600 to find that out :sob:
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  14. 2.0 8v
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    2.0 8v 01 B6 1.8T Quattro saloon

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    [May 10, 2010]
    Have to say your advice in this topic was brilliant! I've had a bad oil leak for a while now and your post helped me isolate it. The breather hose on top of the oil filter housing was brittle and broken. Replaced the hose, o ring, retaining clip, t piece, non return valve, y junction hose onto cylinder head, all clamps and the pressure regulator just past the turbo. The metal pipes were BLOCKED solid, never saw anything like it!!, Oil leak cured, car breathes better, just have to carry out basic settings on the throttle body. All in cost me €90.00 (fitted parts my self). Great tip, many thanks!!
    #13
  15. bowen
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    bowen Member

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    [Nov 21, 2011]
    i would also like to thank blackpool for the help in this topic! Replaced crankcase breather and the car is alot smoother!

    I still get a 17545 (running rich code however?!)
    #14

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