1.8T AUM Engine Vacuum Lines

**joshtomlinson** · 31-10-2008,12:46 PM

Hi Guys,

I was wondering if anyone has replaced all of their vacuum lines on their engine because of

17544 - Fuel Trim: Bank 1 (Add): System too lean - P1136

So far I have replaced the front O2 sensor on the exhaust pipe as the lamda value was all over the shop. But this did not resolve the issue. Light just came back on.

I then changed crank case breather pipe (Y split pipe) as this has a big hole in. This gave a slight improvement to the performance but light still came back on. VW Part code 06A-103-221-AH

Has anyone got a list of all the pipes and lines associated with the vacuum issue. As I can't seem to find them anywhere.

I have not yet replaced the MAF sensor.

Please help!

Josh

**paradigm** · 31-10-2008,01:17 PM

The 'Y' shaped breather pipe you mention, is it the crank case or cam cover breather pipe you mean ? Mine is also split and if that part number is correct it would be a great help. I've also got a leaking vac pipe hidden somewhere underneath the inlet manifold, and I'm getting the exact same symptoms as yourself, at idle the O2 is around 18%, I think the top limit should be 10%. I dont fancy stripping all of the inlet gubbins away to get to this pipe but it may well come to that.

**joshtomlinson** · 31-10-2008,02:57 PM

think its also called the upper PCV hose that has 3 connections to the crack case outlet, lower PCV hose which goes to the sump and intake pipe through a valve after the MAF sensor.

Really easy to change. about £30 for the hose.

I really need to open it up and have a proper look myself.

**joshtomlinson** · 24-12-2008,01:10 AM

Evening Guys and Merry Christmas,

Just incase your having a similar issue to what I've just had. I have just replaced all of the associated pipes for this problem. 52 Plate Mk4 Golf GTI Turbo AUM Engine

Fault Code
17544/P1136 - Fuel Trim: Bank 1 (Add): System too Lean

Don't bother with MAF's or Throttle body alignments, oxygen sensors etc. etc. VW MK4 Golfs around 6 years old will have problems with their vacuum lines due to the high heats the oil sump gas gets. And are the main cause for unmetered air entering the engine intake system bypassing the MAF, therefore buggering up the ECU calculations.

Basically all the pipes from the top of crankcase down to the sump and up to the bottom of the intake manifold were either split or definately on their way. Most notably the crankcase breather hoses and the breather pipe underneath the manifold next to the dip stick (You can just about see them when you take all the plastic covers off.

I would have replaced them with all silicone. But as I may sell on in a few years I wanted to use genuine parts.

Job requires a bit of time, patience and common sense but eventually managed it in a day with my dad. Only falling out once. Haynes manual doesn't help much either if at all.

But this isn't for the faint hearted without some workshop/garage back up just in case. I probably saved myself about £500 or more in labour costs.

The problem is the only way to check if the pipes are split or not is to do what I just did so If your planning to you might as well order the replacement pipes!!

All Parts replaced in no particular order.

(Crankcase - Oil Sump - Manifold Connections)

Crankcase Breather Hose Replaced (VW Genuine Part - 06A103221BH) - 3 Way Connector no major parts have to be removed to change it. (This part had a small hole in it but basically it was f**ked)

Breather Hose Replaced (VW Genuine Part - 06A103213AF) - Connects to 06A103221BH and works its way down to the sump into the t-piece containing the valve.

3-Way Connector & Valve Housing (Swapped the valve from the old T piece) Replaced (VW Genuine Part - 06A103247) - Connect to a plastic pipe into the sump.

Hose Replaced (VW Genuine Part - 06A103221BK) - Connects the t-piece valve to the bottom of the manifold. (This pipe had the worst split!)

I removed the whole section in one piece to check it all. The large plastic pipe was easy enough to remove as it is only held in with a clip. Good idea to make a note of the connections at this point.

(Oil Sump - Manifold - Brake Master Cylinder Connections) - Not essential replacements but changed anyway as it looked like it could affect the vacuum line to the brake master cylinder.

Hose Replaced (VW Genuine Part - 06A133783AS) - Small U Shaped Tube located underneath the mainfold connected to a 3-way valve.

Hose Replaced (VW Genuine Part - 06A133784P) - Small L Shaped Tube Connects to the underneath of the intake manifold

3-Way Connection & Valve Replaced (VW Genuine Part - 06A133529C) - Connects to the right hand side of manifold (very obvious straight swap)

You don't have to remove any serious engine parts except the manifold block everything else was shift out the way just enough whilst replacing parts.

Initial signs that my car is running at lot quieter and smoother even with a Milltek exhaust blowing out the other end and acceleration is a lot smoother as well. So god knows how long this has been running like this before the lights came on. Fingers Crossed!

Regards

Josh

**joshtomlinson** · 24-12-2008,01:14 AM

Pictures attached to the link point to the replacement parts I used.

Found these images on http://www.vagcat.com/ but wouldn't trust the part codes on there just in case. Just take the image to the VW parts shop and tell them what you want.

Hope this helps further

Merry Xmas Everyone

Josh

**paradigm** · 16-01-2009,07:52 PM

Quick update, I've had the rocker cover breather hose and the vacuum hose which travels down past the inlet manifold replaced, it's basically been a miracle cure, all my previous problems (high idle revs and misfires) are now a thing of the past. One VW specialist had the car for a few hours then gave me a load of old gumph that it would cost at least £500 to fix, I got a second opinion from another chap, he did the job with all parts for £125, money well spent in my case.