Have a few questions on a 2004 Passat 1.8t AWM engine

3074 Views 5 Replies 5 Participants Last post by VAGguy, May 12, 2018

avillasenor

Discussion Starter · May 10, 2018

I normally drive an 02 TDI Jetta, but recently bid on an online auction for a 2004 Passat with AWM 1.8t gas engine.
It was advertised as running, driving, stopping condition. Got it for $750.00 which i thought was great. Drove to Phoenix to pick it up and it had a bad miss at idle which dissapears when you give it gas.

I have ross tech Vag Com that i use with my TDI so i hooked it up and measured blocks showing misses in the engine and there were several on each cylinder.
This led me to believe that the coilpacks where probably bad so i went and got brand new NGK plugs and coilpacks, installed them, and then it popped a code for
Pressure Drop between Turbo and Throttle Valve (check D.V.!)

This led me to the diverter valve. Found it and then clamped off the small hose with channel locks - started car and idle was still rough. Unclamped the channel locks and nothing changed on the idle so i am under the assumption now that the diverter valve probably isnt the problem.

Next i got my mapp gas torch and passed it around every hose i could find looking for a vacuum leak and the engine never changed idle with the torch head anywhere near any hose.

The only thing i can physically see is this 90 degree fitting is cracked. What is this, what does it do, and will this cause bad idle?

Thanks in advance for any help

Anthony

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Iowegian

· #3 · May 10, 2018 (Edited)

̶T̶h̶a̶t̶ ̶l̶o̶o̶k̶s̶ ̶l̶i̶k̶e̶ ̶p̶a̶r̶t̶ ̶o̶f̶ ̶t̶h̶e̶ ̶P̶C̶V̶ ̶p̶i̶p̶i̶n̶g̶ and if it is cracked it can cause a vacuum leak which is the most likely cause of the bad idle. There are many, many threads about the PCV system and vacuum leaks since the plastic bits tend to get brittle with age and crack. There are also various check valves and vacuum jet pumps that can fail, etc. That engine looks pretty clean so hopefully there won't be many issues. One problem with servicing these parts is that it's easy to break parts trying to remove them to get at the ones that are already leaking.

034 motor sports sells a silicone hose version of a PCV replacement system. That is a good option if you plan to keep the car for a while. Otherwise a smoke test can help pin-point vacuum leaks but probably won't help much with the check valves, etc.

edited post since info was wrong...

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