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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FrescoGreen01.5

· #4 · May 11, 2018

Regarding those two hard pipes:
>one is part of the PCV system (top pipe, I believe)
>the other is the air output of the SAIP (secondary air injection pump, generically the "smog pump") and connects to the combi valve at the rear of the engine. The combi valve has a silver-colored top and a vacuum line connection (blue in my picture) and is easily visible. I think this is the bottom pipe (things vary by year, and my Passat is gone).

If the elbow in question is for your SAIP, it won't cause a vacuum leak or any other performance issue. It might cause a P0401 code if it's leaking a lot. The SAIP is a high pressure electric fan that runs 100 seconds on a cold start to help warm up the cats to improve emissions. It's located more or less under the right headlight.

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