Rough idle & misfires

[Flygman]

So my 2.0T A4 B7 is running rough (sputters) on idle and first ~30 seconds of driving after cold starts. The unsteady idle is always present even when warm. You can really hear the RPM dropping ever so slightly as demonstrated in this video:



No codes/CEL were triggered the first 3-4 weeks.

Scanned today and got:

• p0302 Cylinder 2 Misfire Detected
• p0300 Random/Multiple Cylinder Misfire Detected
• p0139 Oxygen Sensor Circuit Slow Response (Bank1, Sensor2)
• p1114 Oxygen (Lambda) Sensor; B1 S2: Internal Resistance too High

Tried to replace all coil packs with another set which I know works fine - no success.

I had my entire PCV system replaced 2-3 weeks before this started. It does kind of sound like there is a vacuum leak from one of the PCV hoses, any ideas how to confirm? Brake cleaner?

Going to try cleaning the O2 sensor soon.

Any ideas what to check next?

[ferrara42]

i would say definitely check the o2 sensors, you said you changed the coil packs, but did you change the plugs too? could have good coils but a bad electrode on the plug.

[Flygman]

Don't have any spare plugs available unfortunately, but will try switching them around. Thanks!

[Flygman]

Just ordered a new O2 sensor, might as well replace it when I remove it for cleaning..

[Theiceman]

my vaico PCV lasted 11 days

[Older_not_Wiser]

Remove hose from PCV to IM. Plug IM hole. If it idles fine, then PCV is part of the problem.

[Flygman]

my vaico PCV lasted 11 days

Jesus christ, seriously?

My old valve lasted a year, which I guess is good then??

Remove hose from PCV to IM. Plug IM hole. If it idles fine, then PCV is part of the problem.

Will give it a shot, thanks

[Theiceman]

first vaico lasted 2 years so got another when the diaphragm ripped. second one started throwing lean codes and misfires after 11 days, got a OE one from dealer and is fixed.

[EvolutionArmory]

O2 sensor resistance too high means replace it.

Move some coils and plugs around. If the misfire stays do a compression test. If compression is good, do a leak down test. If leak down is good, replace your injector.

This is all after you replace your rear O2 of course.

I just replaced my rear O2 with a genuine Audi sensor. The plug was different so be prepared for that. Had to buy a connector tool from DAP. They have a nice kit for 25 bucks. Comes with the small and medium release tool and a tool to press in the quick disconnect tabs.

[Jeevan]

Remove hose from PCV to IM. Plug IM hole. If it idles fine, then PCV is part of the problem.

Thats why i got rid of pcv and went with catch can setup. PCV is annoying and needs constant attention


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[esandes]

Thats why i got rid of pcv and went with catch can setup. PCV is annoying and needs constant attention


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Constant attention?

[Jeevan]

Constant attention?

test > failed > replace > worry


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[Flygman]

Would go for catch can if not illegal

[Jeevan]

Would go for catch can if not illegal

what world are you from?


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[Flygman]

what world are you from?


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Sweden. It's illegal in EU to modify your vehicle at all (even springs/coilovers, exhaust, intake etc if the annual inspection guy is an asshole).

You can get away with a lot until you start doing engine mods.

Compared to some US states where you can drive around like this..

[Jeevan]

Sweden. It's illegal in EU to modify your vehicle at all (even springs/coilovers, exhaust, intake etc if the annual inspection guy is an asshole).

You can get away with a lot until you start doing engine mods.

Yeah I watched Youtube videos about how Germany, Switzerland and Sweden inspections can be Dics when it comes to inspection. I saw people spending 1000 Euro's for spark plugs in switzerland @200 Euro an hour lol

[Flygman]

Well Swiss people are just filthy rich, of course you can change your own spark plugs lol

[Brillo]

Don't really recommend a cc in Sweden. They are not without their own set of problems, especially in cold climates. Just for your information, it is also illegal to modify the pollution control system in all 50 US states. However, chances of getting caught are quite low.

I doubt the PCV system is the cause of all your issues but it's easy to assess without spending a dime. An earlier post suggested this: "Remove hose from PCV to IM. Plug IM hole. If it idles fine, then PCV is part of the problem." This test is overly simplistic and almost worthless, and possibly misleading. There are better ways to test the PCV system. First, make sure the rubber gasket on the oil fill cap and O-ring on the dipstick are intact. Carefully pop off the round cap on the PCV valve and inspect the rubber diaphragm for tears. Check the small valve at the diaphragm's center and then clean the mating surface seat inside the valve. Replace the diaphragm and cover. Remove the tube from the PCV valve to the IM and check for cracks (leaks) and check the O-rings at either end. Remove the tube from the oil filter housing that goes to the most rear port of the PCV valve and check for cracks (leaks) and check it's O-rings. Carefully replace both tubes. Now remove the tube from the right front of the VC to the pre-turbo port. Plug both holes. Start your engine and see if it idles smoothly but do not run up the RPMs in this condition. Test the check valve at the top of this tube to make sure no gas can pass going towards the VC. If everything is good you likely don't have a PCV system problem. If you have to replace the PVC valve go with OEM as Theiceman suggests. Good luck. Brillo

[esandes]

test > failed > replace > worry


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Test > failed > replace > your posts > your knowledge about audi

[Jeevan]

Test > failed > replace > your posts > your knowledge about audi

well this post https://www.audizine.com/forum/showthread.php?t=896859
explains your knowledge about cars and how handy your skillset is. I bet you should worry about gaining knowledge and try work on your car first instead of pointing your butter fingers at others for no reason

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[ferrara42]

well this post https://www.audizine.com/forum/showthread.php?t=896859
explains your knowledge about cars and how handy your skillset is. I bet you should worry about gaining knowledge and try work on your car first instead of pointing your butter fingers at others for no reason

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WRECKED lol

[mc_hotmail]

It's illegal in EU to modify your vehicle at all

That's capitalism learning from communism/socialism/totalitarianism: I sell you something and buy the government to force you to give me more money to fix it.

Yeah, cheap PCV are waste of money. My last one lasted a month: Yet another PCV test and quick fix method

[esandes]

well this post https://www.audizine.com/forum/showthread.php?t=896859
explains your knowledge about cars and how handy your skillset is. I bet you should worry about gaining knowledge and try work on your car first instead of pointing your butter fingers at others for no reason

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All of your posts are trash. You're a noob here. Useless. People like you drop the credentials of this forum.

[Jeevan]

All of your posts are trash. You're a noob here. Useless. People like you drop the credentials of this forum.

go back to your mommy little girl. Car Forums are for real wrenchers and enthusiasts who wants to learn. Karens like you need to stay away from cars. Time for for you go to your daddy and ask him about Ratchets and wrenches.

Dont bother responding to this comment anymore and try to get a life without hating others.




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[hammond]

All of your posts are trash. You're a noob here. Useless. People like you drop the credentials of this forum.

Are you that lonely to rub others on this forum without much of a reason? Let us know if you lost your job and GF, we will open a GofundMe page for you. Respect others or you will be kicked out of forum.

[esandes]

go back to your mommy little girl. Car Forums are for real wrenchers and enthusiasts who wants to learn. Karens like you need to stay away from cars. Time for for you go to your daddy and ask him about Ratchets and wrenches.

Dont bother responding to this comment anymore and try to get a life without hating others.




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This forum isn't for you. Read, absorb and don't post is my advice for you. How long did you own an audi for? What mods have you done? What wrenching have you done besides your small wang?

[esandes]

Are you that lonely to rub others on this forum without much of a reason? Let us know if you lost your job and GF, we will open a GofundMe page for you. Respect others or you will be kicked out of forum.

I don't need your approval or permission for anything. Where's your respect?

[Jeevan]

This forum isn't for you. Read, absorb and don't post is my advice for you. How long did you own an audi for? What mods have you done? What wrenching have you done besides your small wang?

Enough Mods on multiple cars in my garage that your chicken Brain cant understand. Now, Leave me alone Karen

[esandes]

Enough Mods on multiple cars in my garage that your chicken Brain cant understand. Now, Leave me alone Karen

Answer my questions.

- - - Updated - - -

I've had enough of your crap talking of audis when you clearly have no clue.

[Jeevan]

Answer my questions.

- - - Updated - - -

I've had enough of your crap talking of audis when you clearly have no clue.

come back to me when you know the difference between Engine oil and atf

here you go more fun information on your car knowledge

https://www.audizine.com/forum/showthread.php?t=856652


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[esandes]

The thing you fail to understand is I don't want or need to "come back to you". You're less than a cockroach.

[Jeevan]

The thing you fail to understand is I don't want or need to "come back to you". You're less than a cockroach.

thanks ratta.


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[Jayz691]

When the pcv system was replaced, did they change the metal breather pipe with correct one? There is an earlier and later revision, where they moved the check valve. If no check valve, id imagine that could def cause an issue... And pull cover off of pcv valve to inspect. You can blow into PCV and see if that check valve also seals, bit its seperate from the diaphram.

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[EvolutionArmory]

Test > failed > replace > your posts > your knowledge about audi

Pot, meet kettle. 🤣

[Flygman]

What the fuck did this thread turn into

[Flygman]

That's capitalism learning from communism/socialism/totalitarianism: I sell you something and buy the government to force you to give me more money to fix it.

Yeah, cheap PCV are waste of money. My last one lasted a month: Yet another PCV test and quick fix method

It's not illegal to repair your vehicle, just to put parts on it that have not been tested and approved for the road.

[Flygman]

Ended up switching around the coils once more and now it runs great again.

Two of the four coil pack connector tabs are broken off so I think they just weren't fully connecting. Runs great after really pushing the connectors in place.

[Black Jack]

Ended up switching around the coils once more and now it runs great again.

Two of the four coil pack connector tabs are broken off so I think they just weren't fully connecting. Runs great after really pushing the connectors in place.

That's good. FWIW, I just did some similar work and I found my OEM plug gaps to be out .010 from least to most worn, and after replacing + gapping all plugs, the idle was significantly smoothed.

[Flygman]

That's good. FWIW, I just did some similar work and I found my OEM plug gaps to be out .010 from least to most worn, and after replacing + gapping all plugs, the idle was significantly smoothed.

Nice thanks for the suggestion, although I use iridium plugs which I'm pretty sure you are not supposed to gap