Here are the symptoms:

When I'm cruising at 20-25mph in 4th gear, and I give it a good amount of throttle, the car just doesn't start to pick up until the rpms wind up. While the rpms are winding up, there is a loud "hissing/pulsating" noise that I hear - its a lot louder when I'm next to a wall since it reflects the sound back to me. And its definitley not normal. It only seems to hiss when there is a high load on the car at low rpms.

I know a CAI will make a "sucking" sound - but this is a much higher pitched hissing sound, and it slightly pulses with the exhaust.

Now, at first I thought this was an exhaust leak, maybe a leaking primary slip tube, but then I started thinking it might be a vaccum leak, or maybe even weak spark.

At upper rpms, the car feels pretty good - its just at the 1k-3k rpm range that the car seems gutless and doesn't accelerate well.

Its not a burnt plug wire either - the car rides pretty smooth, doesn't buck/shake.

If anyone has any ideas, or suggestions, anything would help out.

Thanks!

 

ah, thanks killer jello. I guess I can rule out vaccum.

That leaves my suspects as exhaust leak or weak spark.

THe reason I think it might be weak spark was that when I burned my #8 plug wire, the exhaust was gurgly, and the engine sounded especially "chuggy", with the hissing all over the place.

I usually thought exhaust leaks were more "ticks" - but on my car, I can't hear any ticks or hisses at idle - the hissing only starts when I get on the gas and put a load on the car.. revving in neutral won't make it hiss either

 

You say low end sucks a bit (I can hear it chug), and that low RPM high load it makes the noise the worst, maybe it is a vacuum leak. We can check that when we look at your MAP numbers, and you also said your intake is leaking, so a few things are going together that could point to vacuum leak.

 

I had that problem once. All I did was tighten my 2 loose back sparkplugs

 

Zjoker - I think you hit the nail on the head here - I found a really loose (i could spin it with my fingers) spark plug on #8. However, I tightened it and after about 10 seconds, the hissing came back. I wonder if there's another loose plug, or the same plug just backed out..

thanks I'm heading down to the car now to tighten all my plugs.