03 AMB 1.8t leak issue

[NWB6]

Hello all, I am having a vacuum leak issue with my 2003 a4 1.8t quattro amb engine. When I first took possession of the car, it idle really rough, lacked power and had both the CEL light and esp light on. At that time i only had ONE code when i ran it with an obd2 reader. The code was a p0102 for mass air volume input low. Since it had the ESP light on too, I figured it was the MAF. I replaced the brake light switch, my broken suction jet pump too before doing the MAF just incase. Didnt fix my problem so I went ahead and replaced the MAF.

After replacing the MAF, the ESP light went away and I am finally able to turn traction control on and off

Except the CEL light came back! This time, the P0102 light did not return, indicating my MAF problem was solved, however i had some new codes this time,

-Some misfire codes P0300,P0301,P0302
-And P0171 for system too lean bank 1

These codes were new after i replaced the suction jet pump, leading me too believe i messed something up while wrestling that sucker out.(and not merely a coincidence or something indicating o2 sensor or ignition coils) I checked the area only where I was working since the codes only appeared after that, and I found nothing leaking or loose.

After some research I found multiple people who Indicated their PCV valve was the culprit, and too do the Oil Cap test, Sure enough it was hard to remove and there was suction from the cap hole/crankcase. Figured i must have been to harsh on it and broke it or something? My next step is to replace the PCV.

My issue however, is that for every search I do people claim the PCV valve to look 3 different ways.

The one Im suspecting looks like this:



But all replacement parts claim it too look like this? With No clarification if the part was superseded and redesigned or what. Also people claiming its under the intake manifold but mine is right behind it towards the firewall and easily accessible:




Lengthy post, but would appreciate your input, opinions or clarifications. Just when I thought the MAF would fix my idle and rid me of the ugly CEL light something else pops up

[old guy]

That first pic is one of several check valves. The second pic is the PCV valve. If you have a late '03 model yours will be slightly different.

[NWB6]

I see, and is this T fitting usually the culprit that causes the tight oil cap?

[NWB6]

I'm sure I have the T style instead of the second picture style. Is this T pcv valve located under the manifold?

[old guy]

I see, and is this T fitting usually the culprit that causes the tight oil cap?

Yes

I'm sure I have the T style instead of the second picture style. Is this T pcv valve located under the manifold?

Yes

[old guy]

and while you are replacing the PCV you should also replace the "T" and "L" hoses because they will probably disintegrate when you remove the PCV: Clicky click®

[NWB6]

perfect, thanks for your help. Also, if i were to find someone locally with vagcom, would that help pinpoint the source of error codes? Just to avoid guess and check work and throwing parts at the car? Youre awesome man

[old guy]

perfect, thanks for your help. Also, if i were to find someone locally with vagcom, would that help pinpoint the source of error codes? Just to avoid guess and check work and throwing parts at the car? Youre awesome man

Vagcom or VCDS is a tool to help you diagnose different issues. It won't necessarily give you an exact answer as to what to do. It all depends upon the issue. Often it can if it's an electrical issue but that isn't always the case. With mechanical issues it can help with the diagnosis but not necessarily give you the exact cause.

You have a problem with your block breather system. The extreme vacuum at the oil cap at idle is an indication that your PCV is pulling excessive vacuum. You may also have a leak somewhere else in the block breathers that is causing the P0171 and consequently the misfires.

I would recommend starting with correcting the block breathing system. Here's a thread that should help make sense of all the vacuum hoses and check valves. Clicky click®

Happy wrenching

[NWB6]

thank you wise old guy!