1995 Sonoma

[JWFlyfisher]

I have a '95 2.2 4-cylinder Sonoma and am losing power at higher rpms. It basically feels like I am pulling a heavy load and the engine noise gets louder. I have replaced fuel pump, fuel filter, checked fuel injectors, and had it in for a diagnostic test and they said the cat. converter was fine. I'm thinking maybe the EGR valve? Any thoughts appreciated. Power loss happened overnight so I'm thinking something is stuck somewhere. Lose power going up hills or even against a strong wind.

[Airjer_]

Locked up fan clutch?

[JWFlyfisher]

How do you check for the fan clutch? Runs fine at low rpms. Mechanic had tested the clutch thinking it was slipping, but said it was fine.

[Airjer_]

With the engage off, maybe disconnect the negative cable end just to be on the safe side. Try to turn the fan. If it turns easily than never mind its probably not it. It if doesn't turn at all than you found your problem.

The other thought is that the cat is plugged and your hearing exhaust trying to escape between the manifold and the cat. Does it sound like an exhaust leak?

[JWFlyfisher]

Not the fan. Just checked it.

Yes, it does sound like an exhaust leak. Had the back pressure checked but they said it was fine (although I wasn't too impressed with the guy and not sure if he really knew what he was doing). That is what i initially thought that it was but i don't have the equipment to test the back pressure. At idle it sounds fine and there is exhaust coming out of tail pipe.

[Airjer_]

Two things you can try either remove the exhaust from the manifolds and see if performance improves. I make no guarantees on what could go wrong with open headers (fires, melting components, etc). Although I have done this many times without incident.

or

Remove the front o2 sensor, again making no implication that nothing will happen and drive it. Either way you will eliminate all or some of the cat and if it is plugged than performance should increase!!

[DAVE BANKS]

hey my 94 4.3 did the same thing, the platinum in your cat might be melted.and restricting flow, if so just knock all that shit outa there.
i had the exact same problem

[old_master]

Originally Posted by DAVE BANKS

hey my 94 4.3 did the same thing, the platinum in your cat might be melted.and restricting flow, if so just knock all that shit outa there.
i had the exact same problem

Tampering with the emission control system is against the law, even if it's your own vehicle! It carries a fine of $3500 by the US EPA, and possible jail time also, no questions asked! It's probably not a good idea to call attention to the fact that YOU did it! Please don't offer illegal advice to other members on the forum.