2002 pontiac grand prix 3.1 L?

(2011-06-17 14:15:09) 1. dannyboy445 Says: I have a 3.1 the hisses at higher RPMs and under load. but idling it's fine. I think it's the intake gasket but not 100% sure.
Have not done a vacuum test yet. Replaced EGR valve and Oxygen sensor due to code saying they were bad and they were pretty rough when i took them off.

Any ideas?

Thanks!!2. Chris Says: I am very familiar with that engine and it is very likely that you have intake gasket problems. Luckily though for you it's a super easy replacement that won't break your budget if you're mechanical minded - which it sounds like you are. Gaskets from your local parts hut won't cost you any more than twenty bucks, and can be replaced easily in an afternoon. Be sure you get the UPPER INTAKE gasket kit - and not the full intake kit. It should be right as rain after you're done.3. nascarsdf Says: Your thinking seems right to me. It very well could be the intake gasket or some other part of the intake. If it is not the intake, then it may just be the engine under load. Either way it does not seem like a huge problem, so if you can not find the source I would not worry too much.4. Terry Says: the egr port may be pluged to check take the throttle body off and look Tag: 2002 pontiac grand prix 3.1 L?