Audizine - An Automotive Enthusiast Community

Results 1 to 36 of 36
  1. #1
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Can a valve cover pcv leak cause misfires?

    Guest-only advertisement. Register or Log In now!
    I've recently been getting a cylinder #1 misfire CEL on cold starts. I've tracked the misfire count with my scanner and it only shows a couple misfires right at start up and none once it's running for a few seconds. My engine is also consuming oil which I'm fairly certain is due to cracked pcv passages in the valve cover although I haven't verified that yet. So I'm wondering if the pcv leaks in the valve cover could be causing misfires on start up or if I need to start thinking about chasing down another cause. I replaced the coil packs and plugs in October so I'm fairly certain that's not the problem. I also had a carbon cleaning done around that time. I was chasing a cylinder 2 misfire at the time which eventually was traced to a bad fuel injector but I'd rather not replace injector #1 if I don't have to.

  2. #2
    Senior Member Four Rings Theiceman's Avatar
    Join Date
    Feb 15 2016
    AZ Member #
    368804
    Location
    Cambridge Ontario

    yes theoretically it can , so what you are looking at is realms of possibility . a cracked passage can allow both unmetered air into the system as well as oil . lean conditions due to unmetered air can cause misfires as well oil injsted fouling the plug. You actually want a rich condition on cold start so yeah lean condition would do it .
    However what are the possibilities this is your cause ?? would have to be a pretty big leak and I would think it would affect more then one cylinder...

    My advice is fix what you see before you try and fix what you cant see.. In other words fix your known issues first and work from there.
    2014 A4 2.0TQ Technik
    2006 A4 2.0TQ 6spd
    1978 Porsche 911SC Targa
    1976 Yamaha XS 360

  3. #3
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Got another misfire cel today. Hooked up my scanner after it sat for about 3 hours and it started stumbling pretty bad. Scanner showed several misfires on cylinder 1 and one or two misfires on cylinder 3 which coincided with the stumble. Ran fine after turning the car off and restarting. Coil packs are 3 month old Boschs and plugs are same age NGK laser platinums. PCV and breather are new. Not really sure where to start chasing this down. Does valve cover still make the most sense. Could cam chain tensioner play into this?

    Sent from my moto x4 using Audizine mobile app

  4. #4
    Veteran Member Four Rings vvenom800tt's Avatar
    Join Date
    Dec 04 2011
    AZ Member #
    84791
    Location
    Kansas City, KS

    Quote Originally Posted by texadelphia View Post
    Got another misfire cel today. Hooked up my scanner after it sat for about 3 hours and it started stumbling pretty bad. Scanner showed several misfires on cylinder 1 and one or two misfires on cylinder 3 which coincided with the stumble. Ran fine after turning the car off and restarting. Coil packs are 3 month old Boschs and plugs are same age NGK laser platinums. PCV and breather are new. Not really sure where to start chasing this down. Does valve cover still make the most sense. Could cam chain tensioner play into this?

    Sent from my moto x4 using Audizine mobile app
    Swap coils around and quit guessing. Also double check torque on spark plugs.

    Sent from my SM-G960U using Audizine mobile app
    2005.5 Audi A4 Quattro 2.0T 6MT - APR - 034 - Custom 3" single exhaust - 17z Brembo - GFB - Alzor - Kumho - ST - Injen - Swift - Hyperco - ECS - Saikou Michi - PowerFlex - Podi

  5. #5
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    You probably need a carbon cleaning, plain and simple.

    The key word here is cold start. If your car misfires during cold starts but runs pretty good or fine for the rest of the day, thatís a classic case of carbon build up or maybe even the beginning of an issue with the intake runner control motor.

    Have the intake valves ever been carbon cleaned? If so, how long ago was it?

    You can swap coil packs around if you like but that probably wonít tell you anything. Coil packs usually misfire all the time when they go bad, not sporadically.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  6. #6
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    I'll check the spark plug torque but I installed them to spec.

    Carbon cleaning was done 4000 miles ago with walnut media.

    How does one troubleshoot the intake control motor?

    Sent from my moto x4 using Audizine mobile app

  7. #7
    Veteran Member Four Rings vvenom800tt's Avatar
    Join Date
    Dec 04 2011
    AZ Member #
    84791
    Location
    Kansas City, KS

    Quote Originally Posted by EvolutionArmory View Post
    You probably need a carbon cleaning, plain and simple.

    The key word here is cold start. If your car misfires during cold starts but runs pretty good or fine for the rest of the day, thatís a classic case of carbon build up or maybe even the beginning of an issue with the intake runner control motor.

    Have the intake valves ever been carbon cleaned? If so, how long ago was it?

    You can swap coil packs around if you like but that probably wonít tell you anything. Coil packs usually misfire all the time when they go bad, not sporadically.
    But if the misfire moves cylinders then you know its a coil. Which takes 2 minutes to do.

    Ive never had cold start issues so i guess im lucky.

    Sent from my SM-G960U using Audizine mobile app
    2005.5 Audi A4 Quattro 2.0T 6MT - APR - 034 - Custom 3" single exhaust - 17z Brembo - GFB - Alzor - Kumho - ST - Injen - Swift - Hyperco - ECS - Saikou Michi - PowerFlex - Podi

  8. #8
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by vvenom800tt View Post
    But if the misfire moves cylinders then you know its a coil. Which takes 2 minutes to do.

    Ive never had cold start issues so i guess im lucky.

    Sent from my SM-G960U using Audizine mobile app
    Swapped coils and misfire stayed on cylinder 1. Spark plug torque checked out. Likely higher than spec since shop had them out prior.

    Sent from my moto x4 using Audizine mobile app

  9. #9
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    Quote Originally Posted by vvenom800tt View Post
    But if the misfire moves cylinders then you know its a coil. Which takes 2 minutes to do.

    Ive never had cold start issues so i guess im lucky.

    Sent from my SM-G960U using Audizine mobile app
    No question, itís a good test and costs nothing. I was just saying that itís probably not a coil. A bad coil doesnít care if you just started it or if itís been running all day. When they fail, they fail pretty much constantly.

    itís likely carbon build up or tumble flap related.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  10. #10
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    And since the valves were walnut blasted 4000 miles ago, Iíd look at the flap motor.

    To test it you activate its function test or you try to adapt it with VCDS. The test might actually make it throw a fault code if none are present now if it does indeed fail.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  11. #11
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    If the flap motor works during its function test and passes adaptation, Iíd start thinking about injectors or a compression test as the next step as youíve ruled out coils already.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  12. #12
    Veteran Member Three Rings
    Join Date
    Sep 30 2009
    AZ Member #
    48594
    My Garage
    08 A4 2L MT, 87 Jag XJ6, Lex RX350, ~20 Road Bikes, Piper Aztec, Grumman AA1
    Location
    Indiana

    Change the spark plug positions too. It's rare but you could have a bad spark plug.

  13. #13
    Veteran Member Four Rings vvenom800tt's Avatar
    Join Date
    Dec 04 2011
    AZ Member #
    84791
    Location
    Kansas City, KS

    Quote Originally Posted by EvolutionArmory View Post
    No question, itís a good test and costs nothing. I was just saying that itís probably not a coil. A bad coil doesnít care if you just started it or if itís been running all day. When they fail, they fail pretty much constantly.

    itís likely carbon build up or tumble flap related.
    Good to know

    Sent from my SM-G960U using Audizine mobile app
    2005.5 Audi A4 Quattro 2.0T 6MT - APR - 034 - Custom 3" single exhaust - 17z Brembo - GFB - Alzor - Kumho - ST - Injen - Swift - Hyperco - ECS - Saikou Michi - PowerFlex - Podi

  14. #14
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    I attempted to check the flapper position with my ECS Foxwell scan tool. When I check live data for channel 143 I get the flapper position value of 99.6%. It seems to stay there regardless of what I do with the throttle. Is this normal? My understanding from this is that it's supposed to drop to 0% above 2500 rpms. I don't have a VCDS and the Foxwell scanner support is terrible so I'm not sure if I'm looking at this correctly. I'm also not sure how to adapt it with the Foxwell. Any thoughts?

  15. #15
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    Basic settings, car at idle, block 142, not 143. After adaptation passes, switch the ignition off for 60 seconds and turn it back on and check for codes again. If it fails the adaptation, thatís probably your issue.

    I just looked up the instructions for the Foxwell. Page 43 of the manual tells you how to use basic settings. It uses the same VCDS block number.

    http://bd8ba3c866c8cbc330ab-7b26c6f3...can_ToolR1.pdf
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  16. #16
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    I have another couple questions. Is your car a 2005.5 or early 2006 and do you have a JHM tune by any chance? Their tunes used to make peopleís cars have bad cold start problems, but only if they changed your ECU number from a B to a M.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  17. #17
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by EvolutionArmory View Post
    I have another couple questions. Is your car a 2005.5 or early 2006 and do you have a JHM tune by any chance? Their tunes used to make peopleís cars have bad cold start problems, but only if they changed your ECU number from a B to a M.
    It's a 2008 bone stock Avant S-Line.

    Thanks for the scanner manual. I bought mine on Ebay and the paper manual that came with it is pretty useless. Were you able to find that on ECS's site?

    Also, I did some searching yesterday and this sounds A LOT like what I'm experiencing on top of occasional exhaust smoke and oil consumption. It's got me wondering if everything can be traced back to a pcv leak in the valve cover. So if the intake runner adaptation yields no faults, I may just replace my valve cover, which I've been considering for the past month.

  18. #18
    Stage 2 Banner Advertiser Four Rings Hugh@EuropaParts's Avatar
    Join Date
    Aug 22 2010
    AZ Member #
    63043
    Location
    Piscataway, NJ

    Cold start misfire is usually an injector. Some of these cars are approaching 15 years and it's becoming much more common. The injector leaks a bit while the car is off and when it starts up there's your misfire.
    Hubert
    EuropaParts.com, Your Trusted Audi Parts Source
    Phone: 800.877.7033 x 101
    Email: hubert@europaparts.com
    Facebook: Like Us on Facebook


  19. #19
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by Hugh@EuropaParts View Post
    Cold start misfire is usually an injector. Some of these cars are approaching 15 years and it's becoming much more common. The injector leaks a bit while the car is off and when it starts up there's your misfire.
    I'm keeping that in the back of my head as well. I had a misfire when I first bought the car which came down to replacing the injector. Is there a way to test injector health without physically removing/inspecting the injectors?

  20. #20
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by EvolutionArmory View Post
    Basic settings, car at idle, block 142, not 143. After adaptation passes, switch the ignition off for 60 seconds and turn it back on and check for codes again. If it fails the adaptation, thatís probably your issue.

    I just looked up the instructions for the Foxwell. Page 43 of the manual tells you how to use basic settings. It uses the same VCDS block number.

    http://bd8ba3c866c8cbc330ab-7b26c6f3...can_ToolR1.pdf
    Adaptation was successful. I turned off the key and waited 60 seconds and then started the car. I ran a code scan and didn't find any faults although it was idling rough for about 30 seconds or so while the scan was running. No CEL though which isn't surprising. I don't always get a CEL when it has that initial misfire issue.

  21. #21
    Active Member Two Rings
    Join Date
    Nov 09 2016
    AZ Member #
    384998
    Location
    Ohio

    You said you have a crack in your valve cover? Previous poster is correct that can cause lean condition. Check your fuel trims. I have the same scan tool and love it, hated dragging laptop out. However, I use torque pro for LTFT and STFT. ECU doesn't use O2 info until closed loop but will use what was last reported. Example if your fuel trim is 30% it's lean and dumping fuel -30% rich decreasing fuel. Could effect plugs cause misfire.

  22. #22
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by jason96r View Post
    You said you have a crack in your valve cover? Previous poster is correct that can cause lean condition. Check your fuel trims. I have the same scan tool and love it, hated dragging laptop out. However, I use torque pro for LTFT and STFT. ECU doesn't use O2 info until closed loop but will use what was last reported. Example if your fuel trim is 30% it's lean and dumping fuel -30% rich decreasing fuel. Could effect plugs cause misfire.
    I suspect I have a crack in the valve cover based on symptoms and age of the car but I haven't confirmed that. I'll take a look at the fuel trim numbers though and see what I can gather.

  23. #23
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    Quote Originally Posted by texadelphia View Post
    Adaptation was successful. I turned off the key and waited 60 seconds and then started the car. I ran a code scan and didn't find any faults although it was idling rough for about 30 seconds or so while the scan was running. No CEL though which isn't surprising. I don't always get a CEL when it has that initial misfire issue.
    Now that we have that very common failure ruled out, we can start looking at other issues.

    Letís look at things that cause single misfire issues. A spark plug, a coil, an injector and compression of the cylinder that is misfiring. Youíve ruled out spark so the next thing I would do is a compression test. If all 4 cylinders are basically even, thatís good. If one is drastically lower than the others or under 130 PSI, thatís bad. If compression is good itís probably safe to say itís injectors.

    I donít think youíre looking at a PCV issue as that would probably cause misfires on multiple cylinders and not be sporadic. Of course, itís real hard to say without the car being in front of me.

    All we can do is rule stuff out with tests.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  24. #24
    Active Member Two Rings
    Join Date
    Nov 09 2016
    AZ Member #
    384998
    Location
    Ohio

    One negative on the tool is yes you can graph, I just did yesterday off of live data. Unlike vcds can't easily post on here.

    I'm no expert I actually have been studying what I can for free and watching YouTube videos from scannerdanner and South Main auto good stuff. Fuel trims can help you track down issues.

  25. #25
    Established Member Four Rings
    Join Date
    May 20 2017
    AZ Member #
    399735
    Location
    New Hampshire

    Did that make sense? The PCV is global to the engine so a bad PCV would most likely cause all cylinders to run bad, or at least more than one if that was the case.

    For single cylinder misfires you have to stick to things that are specific to that cylinder. Air, fuel and spark delivery.
    2005.5 A4 Avant: JHM K04R, GIAC K04 tune, NGK BKR8EIX plugs, RS4 PRV, RS4 fuel pump controller, Treadstone TR6 intercooler core with JHM pipe kit, CTS Turbo test pipe, ECS Tuning snub mount, 034 street tranny mount, 034 street motor mounts, ECS Tuning turbo inlet pipe, ECS Tuning RA4 clutch conversion, Billy Boat Stealth cat back, Fluidampr

  26. #26
    Active Member Two Rings
    Join Date
    Nov 09 2016
    AZ Member #
    384998
    Location
    Ohio

    I completely agree on compression test.

    I know you have the scan tool so recommended gathering info you can get for free other than some of your time.

    Pull the plugs and post pics too. Let us know which is 3rd cylinder

  27. #27
    Stage 2 Banner Advertiser Four Rings Chris@EPL's Avatar
    Join Date
    Jun 23 2011
    AZ Member #
    77278
    Location
    CT

    Should always get the injectors flow tested, cleaned and screens/seals replaced when doing a carbon cleaning.
    European Performance Labs
    http://www.facebook.com/EPLabs
    https://www.instagram.com/eplabs/
    (203-345-6499)
    Chris@eplabs.net

    Please feel free to contact us with any questions!!

  28. #28
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by EvolutionArmory View Post
    Did that make sense? The PCV is global to the engine so a bad PCV would most likely cause all cylinders to run bad, or at least more than one if that was the case.

    For single cylinder misfires you have to stick to things that are specific to that cylinder. Air, fuel and spark delivery.
    That does make sense. But when I start the car and watch the misfire count on my scanner, although there are more misfires on cylinder 1, I do get a couple on cylinder 3 as well, which made me think that if the vacuum leak is minor enough, it might affect the "weakest" cylinders first. Like maybe the #1 and #3 injectors are the most out of spec or have the weakest spark or something like that so the vacuum leak affects them enough to cause misfires. Maybe that's faulty logic though.

    As far as compression, I had a compression and leak down test done in October and this is what the shop reported:

    "Performed compression test on all cylinders. 205 psi to 210 psi on all 4 cylinders - good.
    Performed leak down test on cylinder 2. 5% leak down - really good, especially with cold engine."

    I guess that leaves injectors. If it is injectors, I'm not going to do that in my driveway in the middle of winter so that will be a shop visit. When they replaced injector #2 for the previous misfire the bill was $600. So my thought was spend $300 on a valve cover and install it myself since I have the oil consumption/WOT smoke issues anyway and see if the misfire magically disappears. If not, bite the bullet and put it in the shop for new injectors. Unless there's a way I can diagnose the injectors without tearing the engine apart. Does looking at fuel injector quantities get you anywhere with that?

    Quote Originally Posted by jason96r View Post
    I completely agree on compression test.

    I know you have the scan tool so recommended gathering info you can get for free other than some of your time.

    Pull the plugs and post pics too. Let us know which is 3rd cylinder
    If I get home before dark tonight I'll look into pulling the plugs and see what they look like.

    Quote Originally Posted by Chris@EPL View Post
    Should always get the injectors flow tested, cleaned and screens/seals replaced when doing a carbon cleaning.
    I don't know the details of what all was done after carbon cleaning as the dealer had this done at his preferred shop before I bought it and I never talked to them directly about it.

  29. #29
    Stage 2 Banner Advertiser Four Rings Chris@EPL's Avatar
    Join Date
    Jun 23 2011
    AZ Member #
    77278
    Location
    CT

    The injectors would have to be sent out to be tested and cleaned. I would make sure that the carbon cleaning actually was done.
    European Performance Labs
    http://www.facebook.com/EPLabs
    https://www.instagram.com/eplabs/
    (203-345-6499)
    Chris@eplabs.net

    Please feel free to contact us with any questions!!

  30. #30
    Established Member Two Rings a1dan_87's Avatar
    Join Date
    Mar 07 2018
    AZ Member #
    415178
    Location
    Utah

    Quote Originally Posted by texadelphia View Post
    I've recently been getting a cylinder #1 misfire CEL on cold starts. I've tracked the misfire count with my scanner and it only shows a couple misfires right at start up and none once it's running for a few seconds. My engine is also consuming oil which I'm fairly certain is due to cracked pcv passages in the valve cover although I haven't verified that yet. So I'm wondering if the pcv leaks in the valve cover could be causing misfires on start up or if I need to start thinking about chasing down another cause. I replaced the coil packs and plugs in October so I'm fairly certain that's not the problem. I also had a carbon cleaning done around that time. I was chasing a cylinder 2 misfire at the time which eventually was traced to a bad fuel injector but I'd rather not replace injector #1 if I don't have to.
    We had a run in with a possibly cracked valve cover, it drowned the turbo and intercoolers. If it's a ridiculous amount of oil, I would suggest you replace it ASAP

    Sent from my ZTE B2017G using Audizine mobile app

  31. #31
    Established Member Two Rings a1dan_87's Avatar
    Join Date
    Mar 07 2018
    AZ Member #
    415178
    Location
    Utah

    Quote Originally Posted by texadelphia View Post
    Got another misfire cel today. Hooked up my scanner after it sat for about 3 hours and it started stumbling pretty bad. Scanner showed several misfires on cylinder 1 and one or two misfires on cylinder 3 which coincided with the stumble. Ran fine after turning the car off and restarting. Coil packs are 3 month old Boschs and plugs are same age NGK laser platinums. PCV and breather are new. Not really sure where to start chasing this down. Does valve cover still make the most sense. Could cam chain tensioner play into this?

    Sent from my moto x4 using Audizine mobile app
    With my earlier comment, exact same problem here. Replaced PCV parts along with plugs, and a few days later the car went up in smoke on the highway, and the car was only doing this during boost. (pegging it in neutral didn't have an effect, but the second the engine goes under load it would swamp the car with oil). I'd almost bet it's a bad valve cover, and I'd suggest double checking the PCV valve to make sure you've got the right one.

    Sent from my ZTE B2017G using Audizine mobile app

  32. #32
    Veteran Member Three Rings
    Join Date
    Sep 30 2009
    AZ Member #
    48594
    My Garage
    08 A4 2L MT, 87 Jag XJ6, Lex RX350, ~20 Road Bikes, Piper Aztec, Grumman AA1
    Location
    Indiana

    Quote Originally Posted by texadelphia View Post
    That does make sense. But when I start the car and watch the misfire count on my scanner, although there are more misfires on cylinder 1, I do get a couple on cylinder 3 as well, which made me think that if the vacuum leak is minor enough, it might affect the "weakest" cylinders first. Like maybe the #1 and #3 injectors are the most out of spec or have the weakest spark or something like that so the vacuum leak affects them enough to cause misfires. Maybe that's faulty logic though.
    ^^Not faulty logic, and makes some sense. ^^
    I'm surprised you haven't checked your VC for a leak yet. It's so easy to do and you don't even have to remove it from the car! Eliminate that as a possibility before your start fukking around with all that other stuff. Also, you haven't indicated that you've checked the spark plugs. All you've done is re-torqued them. They are 3 months old but that doesn't mean that one of them isn't bad. It's rare but happens.

    It could be an injector. Most shops I'm aware of will clean them during the course of a walnut blast carbon cleaning but perhaps the guys that worked on your engine didn't do it. So faulty injectors still remains a possibility.

  33. #33
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by Brillo View Post
    ^^Not faulty logic, and makes some sense. ^^
    I'm surprised you haven't checked your VC for a leak yet. It's so easy to do and you don't even have to remove it from the car! Eliminate that as a possibility before your start fukking around with all that other stuff. Also, you haven't indicated that you've checked the spark plugs. All you've done is re-torqued them. They are 3 months old but that doesn't mean that one of them isn't bad. It's rare but happens.

    It could be an injector. Most shops I'm aware of will clean them during the course of a walnut blast carbon cleaning but perhaps the guys that worked on your engine didn't do it. So faulty injectors still remains a possibility.
    I'll check both tonight. I guess I never checked the VC because I was having a hard time trying to figure out how to introduce pressure or vacuum. I get shoving the cork in one side but how do I hook up air to the other side? I don't have a compressor or vacuum pump. I guess I could use my bike pump but I'd still need to figure out how to hook that up to the other side of the VC passage. I was thinking another cork with a inflation needle inserted through it which sent me down the rabbit hole of how do I seal that to insure it's air tight? Paralysis by analysis.

    So just visual inspection of the plugs? What would I be looking for exactly?

  34. #34
    Established Member Two Rings texadelphia's Avatar
    Join Date
    Jul 05 2016
    AZ Member #
    375723
    My Garage
    2008 A4 Avant 2.0T Tiptronic
    Location
    Portland, OR

    Quote Originally Posted by a1dan_87 View Post
    We had a run in with a possibly cracked valve cover, it drowned the turbo and intercoolers. If it's a ridiculous amount of oil, I would suggest you replace it ASAP

    Sent from my ZTE B2017G using Audizine mobile app
    I got the PCV directly from the dealer and had them double check compatibility with my VIN so I'm fairly confident there.

    As far as the amount of oil, I guess it depends on who you talk to. It's about a quart every 1200 miles which Audi says is A-OK but is outside my comfort zone, especially considering my compression numbers...although I know compression may not be an indicator of oil scraper ring performance.

    Also, no oil in the intercoolers last time I checked.

  35. #35
    Active Member Two Rings audiericus's Avatar
    Join Date
    Sep 11 2018
    AZ Member #
    426596
    My Garage
    15 RS5, 15 A4 S-Line
    Location
    Chicago

    Audi would say yes. Check coil plug female connectors, coils, plugs to start.

    Sent from my Pixel 3 XL using Audizine mobile app
    Eric
    15 RS5
    15 A4 S-Line

  36. #36
    Veteran Member Three Rings
    Join Date
    Sep 30 2009
    AZ Member #
    48594
    My Garage
    08 A4 2L MT, 87 Jag XJ6, Lex RX350, ~20 Road Bikes, Piper Aztec, Grumman AA1
    Location
    Indiana

    Quote Originally Posted by texadelphia View Post
    I'll check both tonight. I guess I never checked the VC because I was having a hard time trying to figure out how to introduce pressure or vacuum. I get shoving the cork in one side but how do I hook up air to the other side? I don't have a compressor or vacuum pump. I guess I could use my bike pump but I'd still need to figure out how to hook that up to the other side of the VC passage. I was thinking another cork with a inflation needle inserted through it which sent me down the rabbit hole of how do I seal that to insure it's air tight? Paralysis by analysis.

    So just visual inspection of the plugs? What would I be looking for exactly?
    Besides a visual inspection of the plugs just like with the coil packs move #1 to a different cylinder and see if the misfire follows. Like I said though, this is likely not the problem but can't hurt to eliminate anyway.

    You don't need a compressure of vacuum pump. Your idea of the bicycle pump and inflation needle through a second cork will work just fine. A dab of Vasoline can hlep with the cork seals. If the VC seam is bad air will leak out pretty darn fast. You could also jerry-rig a pressure or vacuum brake fluid bleeding system pretty easily if you have access to one.



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
  •  


    © 2001-2019 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.