PCV Valve Misfire.

[PopeBob3rd]

Replaced my PCV Valve and both hoses on my B7 A4. Heard some hissing from the PCV Valve and figured id replace it and the hoses via parts from ECS. After the install the car is misfiring. Did a smoke test and cant find any vacuum leaks, i also reinstalled the old PCV Valve and hoses but car is still misfiring. Any help would be appreciated as i have a funeral to go to in 2 days.

[007J]

ECS has a reputation for sometimes giving the wrong parts, and they have done it to me a few times as well. There are two different types of PCVs for our 2.0t and it depends on your vin / when the car was produced. Did you also replace the breather tube that goes from the VC to the turbo? If you did, do they both look the same inside? Newer years have a check valve in the breather tube, older ones like mine do not. You can also confirm if the PCV is working by blowing into it to see if the valve is opening and closing, just clean it off so you don't get a mouth full of oil. Might be worth trying to run some Royal Purple ignition cleaner for carbon build up. Carbon build up else where is the only thing I can think that would give you a misfire after properly swapping the PCV.

[Hugh@EuropaParts]

If two parts give you the same results you're most likely swapping out parts not associated with the issue.

[PopeBob3rd]

ECS has a reputation for sometimes giving the wrong parts, and they have done it to me a few times as well. There are two different types of PCVs for our 2.0t and it depends on your vin / when the car was produced. Did you also replace the breather tube that goes from the VC to the turbo? If you did, do they both look the same inside? Newer years have a check valve in the breather tube, older ones like mine do not. You can also confirm if the PCV is working by blowing into it to see if the valve is opening and closing, just clean it off so you don't get a mouth full of oil. Might be worth trying to run some Royal Purple ignition cleaner for carbon build up. Carbon build up else where is the only thing I can think that would give you a misfire after properly swapping the PCV.

Ok i will call the VW dealership down the road from me and see if they have the PCV. I replaced the breather tube about 2 months ago when i noticed it was leaking oil. Also did a full carbon clean about 6 months ago when i did the fuel injectors.

[Jayz691]

Just an fyi, blowing into the pcv at the IM port only test the check valve in the elbow, not the diaphram operation. But second making sure ya got the correct one. But since it does it with the old one, im guessing you have a leak. If it wasn't misfiring before, and is now, it's something that you did.

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[Theiceman]

I'm not convinced PCV is the issue here.. did you do a scan or are you using parts cannon..
Especially if you put the original one back and have same issue.
I am under the impression bit was not misfiring until the PCV replacement
Check coils are seated firmly as the clips get broken and you could have jarred one loose.

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[PopeBob3rd]

*Update* Got the new PCV installed and that seemed to help the issue the car doesnt buck nearly as hard as it was. Finally got an OBD11 scanner on it. The codes its currently throwing are P1297 P1093 P2279 as well as static misfire codes across all cylinders. Any help pointing me in the right direction would be appreciated.

[Theiceman]

did you erase all codes? and these are new ones since test driving after the PCV replacement ?

ok i will admit im not sure what " static misfire codes " are compared to other misfire codes ?

sounds like a massive vacuum leak to me . id smoke test the intake tract if you cant find it ..

[PopeBob3rd]

did you erase all codes? and these are new ones since test driving after the PCV replacement ?

ok i will admit im not sure what " static misfire codes " are compared to other misfire codes ?

sounds like a massive vacuum leak to me . id smoke test the intake tract if you cant find it ..

Yes i cleared all codes after the new PCV install so these are all new ones. I had a smoke test done yesterday and they couldn't find any leaks. i suppose it wouldnt hurt to find a different shop to run one again to make sure

[Brillo]

There are two check valves and one diaphragm valve in the PCV system, new and old version. The two check valves are easy to functionally assess. 1) For the check valve in the rear of the main PCV, remove the tube going from the PCV body to the IM at the IM connection. Apply pressure to the tube at the IM end. Absolutely no air should flow through the tube into the PCV valve. 2) for the other check valve (either new or old version) remove the front breather tube at the Pre-TC port and pressurize it. Absolutely no air should pass through the tube into the valve cover.

Would join the others above in the thinking that your problem likely does not relate to the PCV system, but it is easy enough to check it for free.

[Jayz691]

There are two check valves and one diaphragm valve in the PCV system, new and old version. The two check valves are easy to functionally assess. 1) For the check valve in the rear of the main PCV, remove the tube going from the PCV body to the IM at the IM connection. Apply suction to the tube at the IM end. Absolutely no air should flow through the tube. 2) for the other check valve (either new or old version) remove the front breather tube at the Pre-TC port and pressurize it. Absolutely no air should pass through the tube into the valve cover.

Would join the others above in the thinking that your problem likely does not relate to the PCV system, but it is easy enough to check it for free.

Ya wanna apply pressure at the IM hose, not suction. It Keeps boost from entering pcv, from IM. So should seal from IM to pcv.

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[Brillo]

Ya wanna apply pressure at the IM hose, not suction. It Keeps boost from entering pcv, from IM. So should seal from IM to pcv.

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Oops, you're right - brain fart. I'll try to edit my post.