Hello all,

I've been lurking for a while and have searched for this problem and haven't found an answer yet.

I have a 2001 Ford Excursion 7.3L with 35,000 miles on it. I just installed a aFe air intake and Bullydog 4 position switch chip.

On the high horsepower setting I put the pedal to the metal and at times have to let off early about mid shift 1st or 2nd gear, usually because I've run out of street or the race is over. RPMs are climibing quickly, boost is high.

The sound is right when I let off the throttle.

I get a loud pressure release hiss or metal grinding sound from under the hood. In the stock mode I don't get it.

I'm going to install a 4" exhaust system next weekend.

Is this some pressure release from the turbo, or some spooling resonant sound?

Thanks for all your help from many things I've found here in the past.

 

From what I have learned reading here on the forum you are experiencing some compressor noise. Mine barks out the exhaust when I lift and I don't have any mods at all. I don't know if it's harmful or not if it only does it on release. You can improve things quite a bit by changing the turbo configuration. I don't mention anything specific on the turbo specs because there is a lot of choices for that and you need to read up on it and decide what you want to do there.

 

My 2001 CC 250 with the tymar type intake does that with the superchip tuner installed. When you have a lot of boost pressure built up in the intake and then let off the throttle really quick or it shifts up that air pressure goes back out through the turbo sounding like air blowing off. I personally think it sounds neat. I had a Peterbilt with a Holset turbo on it that would do that. I don't believe that it will hurt anything, just that you probably didn't notice it with the stock air cleaner on it