2001 Grand Prix P0108 And High Vacuum Pressure

2001 Pontiac Grand Prix GT 3.8 L V-6 (non-supercharged). Service engine soon codes = p0108. Repairs done prior = Just replaced the upper intake manifold.

I have a 2001 Grand Prix GT (non-supercharged). I just replaced my upper intake manifold due to warping causing a coolant leak. After putting everything back together I have a problem with the vacuum system.

At idle when I take off the oil cap there is way to much suction coming through. It pulls the cap back hard. When I cover it with my hand the engine RPMS go way up and it sounds like the vacuum is starving for air. Is it possible that while replacing the upper intake I spilled coolant into the tube leading to the PCV valve? I checked all vacuum lines and they seem to be all right and hooked up correctly. Also I did not use any extra sealant on the gaskets as I heard this can cause problems. Why does my GP doing this.

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Only thing that can cause this vacuum problem and the MAP sensor code is that either you did not install the PCV valve, the valve O ring is missing, or possible the large plastic insert is not in the new manifold. It should have come with this insert. Look at the inside of the old manifold and you will see a runner insert that can be removed. If this was missing from the new manifold, it could cause this. Be sure the PCV valve is installed. Getting coolant in any tube or passage would not cause this.

You were right on. It was the bottom o-ring for the PCV valve. The new upper intake manifold came with the top o-ring but not the bottom one and it was black rather than orange so I didn't see it down there. After I put the bottom o-ring in the crazy suction was gone. But I am still getting the same problem as I had before I replaced the intake. Code p0108. When cold the car will start, rev up then stall.

It will only stay running if I keep the RPMs at about 2000 till it warms up a bit. I think the coolant leaking into the intake may have caused the MAP sensor to go bad. I am going to try replacing it tomorrow. Unless you can think of something else that might be causing that issue. Thanks again for your help! You were the first one to nail the answer!

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