Hey, my 94 3.4L 5-speed is having a problem accelerating over 3300 RPMs. The car runs fine in lower RPMS but when I open the throttle the engine makes this weird hissing/whistle, the RPMs and speed continue to rise but very sluggishly. For example, yesterday I had to accelerate to pass a car so I dropped it from third to second gear and gave it gas. The car instantly made this supercharger whistle noise and was unable to accelerate much. I'd compare the sound to the sound of a pool pump when its running without water inside of it and to a whistle a supercharger makes.

This only happens while in gear, I can't hear the "hiss" when it's in neutral. I changed the plugs about 8000 miles ago and just put in a new air filter. The oil pressure and engine temperature is normal. My exhaust "coughs" a lot and I think the heat shield is loose because it makes a rattle sound. The fuel injectors and fuel filter haven't been changed for 40,000 miles, could they be clogged and unable to feed the engine gas under heavier-than-normal acceleration?

Has anyone had this kind of problem before? help!

 

How many miles and how old is your catalytick converter?

 

the car has 100,000 miles and the catalytic converter hasn't been changed for the 50,000 miles i've put on it. I think its the original one.

 

Its likely a clogged CAT... That would cause your powerloss up top and in the midrange, and the rattling..

If its factory exhaust you might be able to "unbolt" the CAT off and run the car with an open y-pipe to see if that was your problem or not.

 

thanks, i'm going to take it into the muffler shop.

also, i'm just wondering why the z28 is called the z28? why isn't it z27 or z10 or any other number? i have no idea why i want to know this.

 

Z28 was GMs internal code for the 302 V8 back in the 60's. It later became a trim level designation.

 

Your weard sound could be a cloged cat.
Change the fuel filter too, it should be changed like every 15,000.

 

i had the same kind of problem in my 88, turned out that two spark plug wires were bad almost burnt in half, so maybe just check your wires out real good and take a plug out to look at it