Hi. My son recently replaced his intake manifold on his 1997 Altima and now it will barely idle, and a vacuum gauge oscillates like a madman. After checking all the vacuum hoses for routing and leaks, I listened to the base of each injector with a long rubber hose. I could hear what sounded like a definite hiss on several, so we bought new gaskets that go between the bottom of the injector and the manifold. It didn't seem to help much, so I tried putting a heavy coat of rubber cement around the base of each injector where it goes into the manifold. That smoothed out the idle. Once the rubber cement is peeled off, it reverts back to running like a piece of crap.
The fuel rail seems to offer some movement when you tighten the two bolts down, but just looking down at the injector seat, they don't look properly seated to me.
Is there some way to make sure we are getting these seals seated properly when we tighten the two bolts down? Is there a torque setting for tightening the bolts?
Is there some sort of gasket sealer we should be using? Should we polish the seat on the top of the manifold?
Overall, it seems like a pretty hit or miss design.