Audizine - An Automotive Enthusiast Community

Results 1 to 12 of 12
  1. #1
    Active Member One Ring
    Join Date
    Jul 23 2012
    AZ Member #
    97392
    Location
    Michigan

    2003 1.8t, rough idle, misfire codes, HELP PLEASE

    Guest-only advertisement. Register or Log In now!
    I have a 2003 1.8t, 140,000 miles. recently on a 200 mile trip it started to idle rought and the CEL came on. It read misfires on all cylinders and a lean code. I smoke tested it and found that the 90 degree elbow in the pcv system was leaking, fixed that, and it still is idling rough, but it didn't through the lean code any more, just random misfires. I cleaned and inspected the MAF, it seemed to be clean but i cleaned it anyways. that didnt change anything. I tried unplugging the MAF while it was running, still idles the same rough way. I'm at a loss as to what to check next. with the car running there is some suction on the oil fill cap, but nothing like what people say they experience when they had PCV problems. What possibility could cause the rough idle. Can a bad coolant temp sensor cause issues like this, how about o2 sensors. I plan on re smoke testing to make sure there is no more vacuum leaks tomorrow. i will also check the fuel pressure to see if the pump could be going bad. i really neeed some help with this one. thank you, and ps, the car runs fine when your driving, it only misfires when it idles.

  2. #2
    Site Moderator Four Rings Stubek's Avatar
    Join Date
    Feb 13 2004
    AZ Member #
    401
    My Garage
    2007 Honda Element SC
    Location
    Silicon Valley, CA
    Items for Sale

    coils and plugs.
    Are you getting any CEL now and any codes? If you have a code on one particular cylinder, swap that coil to another and see if the code follows to that new cylinder. If not, do the same with the plug
    Kevin - Moderator, Audizine

    2011 A4 Avant Meteor Grey/Black, Titanium Package, Prem+ Nav, B&O. Euro LED Tail Lights, Tint, LED license plate lights, LED interior lights, custom sub, lots of VAG updates, Eurocode Alu Kruez, Hotchkiss F/R Swaybars

    Build thread: http://www.audizine.com/forum/showth...ead?highlight=

  3. #3
    Active Member One Ring
    Join Date
    Jul 23 2012
    AZ Member #
    97392
    Location
    Michigan

    i just replaced all 4 coils a month ago, new plugs 10,000 miles ago, and it shows its misfiring randomly on all cylinders. it will sometimes have a high idle, then drop back down to about 800 rpm and idle rough.

  4. #4
    Active Member One Ring
    Join Date
    Jul 23 2012
    AZ Member #
    97392
    Location
    Michigan

    i talked to a friend of mine who works at an audi and VW dealership, i noticed that i also threw a ECT sensor 1 code, high resistance. He said that i need to replace the coolant temp sensor behind the head, it sends signals to the ECU to help controll fuel and air ratios, and if its wrong, it will cause similar problems as to what I'm having. Has anyone else ever seen this problem?

  5. #5
    Senior Member Four Rings Charles.waite's Avatar
    Join Date
    Jun 27 2011
    AZ Member #
    77478
    Location
    Seattle, WA
    Items for Sale

    Faulty rear CTS is VERY common and could definitely be at fault here. If you're replacing it it would also be a good idea to replace the Rear Coolant Flange. Its just one of those "while you're in there" things. Yea its a pain but doing both at the same time saves some repetitive work down the line.

    Also just because your PCV isn't leaking, doesn't mean its functioning correctly. I was having rough idle issues until I replaced my entire PCV system with a full 034 Motorsports Silicon PCV kit and went through and replaced every check valve in the vacuum system. Its been idling perfectly ever since.

    Motor mounts and Snub mount could also be culprits for a rough idle, but in my opinion, the PCV stuff is most likely.
    -CP
    USP CLUB MEMBER #136
    2004 A4 1.8TQ 6MT USP - APR Stage 1+ - FSI Coils - BKR7EIX-11 - 034 Rear Swaybar (Soft Setting) and Endlinks - B6S4 Front + B7A4 Rear Brakes - 034 Street Trans Mount
    2008 Brilliant Black Unicorn (2.0t S-Line Ti 6MT Avant) - Bosch FR6KPP332S
    SOLD -- 2006 A4 2.0TQ Avant Tiptronic

  6. #6
    Active Member One Ring
    Join Date
    Jul 23 2012
    AZ Member #
    97392
    Location
    Michigan

    I'll definatly replace the sensor tomorrow, the flange was replaced when i had my head gasket replaced but i dont think they changed the sensor. also how can i check if the pcv system is working? i was looking at other forums and I've seen many threads about people removing alot of the vacuum lines, and the pcv and prv valves. they had diagrams and everything and it looked pretty good and simple when its done. and i probably will see if the check valves are working right and if its still idling bad tomorrow after the sensor, I'll order the parts for the pcv system probably, I really hope the sensor fixes it though. The pcv system seems to be working right, slight vacuum on the oil fill cap, not dificult to remove cap at all, which seems to make since from everything i've read about the pcv system, it holds a slight vacuum in the crank case.

  7. #7

  8. #8
    Veteran Member Four Rings diagnosticator's Avatar
    Join Date
    Aug 26 2005
    AZ Member #
    7741
    Location
    Seattle, WA

    Quote Originally Posted by irunktm View Post
    i talked to a friend of mine who works at an audi and VW dealership, i noticed that i also threw a ECT sensor 1 code, high resistance. He said that i need to replace the coolant temp sensor behind the head, it sends signals to the ECU to help controll fuel and air ratios, and if its wrong, it will cause similar problems as to what I'm having. Has anyone else ever seen this problem?
    Common problem. Replace the sensor first.

    Unless you want to open a can of worms, and make the situation a lot more complicated, do not modify the vacuum hoses or the crankcase ventilation/PCV system. The CV/ PCV system needs maintenance regardless. Make sure all the hoses are tight, and that none are cracked or split. Clogging will cause problems with the PCV system also, evidenced by high crankcase pressure and oil leaks from the engine gaskets and seals. Leaking or clogged vacuum or PCV systems hoses and loose hose connections will cause hard starting and rough running engine problems also.

    Check the function of the several check valves in the vacuum system. Air flow through the check valves must be one direction only. If removed or replaced, make sure the check valves are reinstalled in the same flow direction as originally installed.

    The slightly negatibe pressure you described at the oil fill cap, indicates the crankcase ventilation system is working correctly.
    Last edited by diagnosticator; 07-25-2012 at 01:46 AM.
    Vorsprung durch Technik

  9. #9
    Veteran Member Four Rings A4Maine-iac's Avatar
    Join Date
    May 03 2010
    AZ Member #
    58482
    My Garage
    2011 VW Routan , Silver 08- A4 Kids Size - Kaylah Sticker Mod
    Location
    Maine

    Also 10k on plugs? Which ones? I'd throw in a fresh set as well along with CTS.
    2002 A4 1.8T - sold


    2007 DTM S4

  10. #10
    Active Member One Ring
    Join Date
    Jul 23 2012
    AZ Member #
    97392
    Location
    Michigan

    well as it turns out, it is the pcv system, even though it wasnt like other people described, the crank case vacume was too strong, just by a little bit and it casued my problems. My question is when i pinch off a vacume line from the intake, that leads down to a t fitting thats also connected to the 90 degree plastic elbow from the oil fiter housing, what valve is bad? from my understanding there is a pcv valve and a prv valve, which one do i need to replace?

  11. #11
    Senior Member Three Rings
    Join Date
    Apr 22 2012
    AZ Member #
    92290
    My Garage
    02 b6 avant
    Location
    Fremont, CA

    thats the PCV area PRV is either on back of head or near tip...sometimes called pancake valve

  12. #12
    Veteran Member Four Rings A4Maine-iac's Avatar
    Join Date
    May 03 2010
    AZ Member #
    58482
    My Garage
    2011 VW Routan , Silver 08- A4 Kids Size - Kaylah Sticker Mod
    Location
    Maine

    Scroll down to #5 post. Part #6.

    http://forums.audiworld.com/showthread.php?t=2380970
    2002 A4 1.8T - sold


    2007 DTM S4



Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


    © 2001-2014 Audizine, Audizine.com, and Driverzines.com
    Audizine is an independently owned and operated automotive enthusiast community and news website.
    Audi and the Audi logo(s) are copyright/trademark Audi AG. Audizine is not endorsed by or affiliated with Audi AG.