Need Help! Loss of Power

**01GTLAK** · 10-07-2012

A couple weeks ago my car (3.8 Litre V6 L36) would suck in air when i put some throttle down or when i went to speed up on interstate, i noticed i had a lower intake manifold gasket leaking and figured it was due to that, so i replaced the lower intake manifold gaskets, upper intake manifold gaskets, valve cover gaskets, and throttle body gasket, but the loss of power and air sucking noise still continued. I also noticed i had a plug wire that kept shorting and sparking on the engine bracket so i replaced plugs and wires last night. Took it driving today, still didnt solve the problem. Does anyone know what this could be? When i give it throttle it revs and has no power behind the rev, sounds like air is being sucked in

Thanks

**Scottydoggs** · 10-07-2012

does it sound like a vacuum? just the sucking sound but not much out the tail pipe? if you have no check engine light on, id be thinking clogged cat.

whats your miles on the engine? and year?

**01GTLAK** · 10-08-2012

2001 GPGT 3.8 Non supercharged with 109K on it, i dont think its vacuum, my car runs perfectly fine cold, then when it warms up it starts chugging and losing power on light acceleration

**Scottydoggs** · 10-08-2012

pull the upper 02 sensor off and see if it runs better with the huge exhaust leak.

look under the car at night after driving it to see if the cat is glowing red. when the car is cold get it up and get under it, hit the cat hard with your palm, do you hear anything rattling around inside?

all signs of a bad cat.

**94GrandPrixSE** · 10-08-2012

I second Cat

**01GTLAK** · 10-08-2012

Did a back pressure test on the cat, at idle i had 3 psi of back pressure then with rpms the psi needle pegged all the way, getting a new cat today, hopefully this was the problem, thanks for your help

**rperry435** · 10-08-2012

I gutted my cat but it was doing the same thing. Mine wasn't glowing or smelling bad either...but it was making that sucking of air noise. All is great now... I removed the resonator at the same time

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