I once ran into something similar on a 1.8t Passat. There were two holes in the bottom of the metal cross-over pipe that runs under the radiator. Some previous person had secured the belly pan to the bottom of the car by running sheet metal screws up into what he thought was just unused metal. Another previous person did away with the belly pan and screws. When he did that, he opened up those holes and created a small intake leak. I closed the holes by threading in new screws. Find a short screw that fits your existing hole and thread it in.
Steve, that's what I was tempted to just do - but I wanted to verify first.
I'm thinking the same thing happened - I received this passat with no belly pan so I have no clue.
Should I coat the screw I use in any kind of sealant?
And as a followup, could this leak be related to the other issues I am having in this post: Coils or ICM? ? I thought I had a big vacuum leak - but I wondering if this was it the whole time?
A hole like that can cause inaccurate fueling. Metered air would be escaping from the system during boost and un-metered air would be entering the system when not in boost. The system has some capacity to adapt but the harder it has to work at it the less on-target it will be.
Plug that hole and fix any other leaks your boost test uncovers. Once you get the system air tight and it has a chance to learn its proper fueling correction, it should run better.
Steve, I was kind of thinking the exact same thing - seems to be the only leak I can find - HOWEVER, since its a sizable hole, I may not be able to find any other possible leaks until its sealed and pressures increase.
I'm finally in the right direction though, hopefully this will be the biggest issue for a while; as I'm about to roll over 200k. Timing belt, CCT, and multiple gaskets, PCV parts, and preventative stuff coming up...going to be a busy few days when it does!
You want another mind blowing change in performance? Get the ECU remapped.
Is your system now able to hold some pressure during a boost leak test?
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