New Noise
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Senior User
Joined: Oct 2004
Posts: 127
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From: Fort Lauderdale, FL
New Noise
I just installed AFE Stage II and MBRP 4" exhaust on my 2002 7.3. When I lift off the throtle, I hear a "woosh" type noise under the hood. Everything appears tight. This is unloaded, not towing with the Predator set at 60 HP. My buddy thinks that it is the turbo spooling down.
Any ideas?
Thanks
Anyone have any input?
Any ideas?
Thanks
Anyone have any input?
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Originally Posted by csurp
I just installed AFE Stage II and MBRP 4" exhaust on my 2002 7.3. When I lift off the throtle, I hear a "woosh" type noise under the hood. Everything appears tight. This is unloaded, not towing with the Predator set at 60 HP. My buddy thinks that it is the turbo spooling down.
Any ideas?
Thanks
Anyone have any input?
Any ideas?
Thanks
Anyone have any input?
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
that is because the turbo does not have an inline blow-off valve, or the engine does not have a throttle plate. when the engine slows down in speed, it can not take in as much air in. so the 20 pounds of boost you were making *(just an example) can not get in the cylinders, so it works it's way back through the piping and yes, back out the filter. i think it is awesome, it is somewhat like a blow-off valve sound, without that little inline-4 vroom behind it. it IS perfectly normal, and i myself love it. my dad almost freaked when he heard it for the first time. i then had to explain ^^ to him. you will also notice a constant "sucking" sound when you are beginning to build boost and do not shift gears to change engine RPM... i.e. you are coming up on a hill in OD and you start at 2 pounds boost, but do not need to shift into 3rd, but the boost increases to about 10psi. a fun sound indeed. 
Fleet Mechanic
Joined: Jun 2004
Posts: 1,296
Likes: 1
From: Coal Valley, Illinois
You will learn to love the sounds of a modified PSD. Since I installed my Wicked Wheel, 46637 filter and BTM, I can't stop grinnin'. The guys were right when they said you always want to have your foot in it, need to hear those sounds!
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Originally Posted by hink10
You will learn to love the sounds of a modified PSD. Since I installed my Wicked Wheel, 46637 filter and BTM, I can't stop grinnin'. The guys were right when they said you always want to have your foot in it, need to hear those sounds!
That turbo just spins and spins and SPINS. 
Fleet Mechanic
Joined: Jun 2004
Posts: 1,296
Likes: 1
From: Coal Valley, Illinois
Originally Posted by Kwikkordead
Wait'll you tow something up a hill. That turbo just spins and spins and SPINS.
That turbo just spins and spins and SPINS.
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Junior User
Joined: Oct 2005
Posts: 76
Likes: 0
From: Adairsville,Ga
There is somthing wrong with your truck! Is what I here from parking lot patrons when they hear Spooldown. (I only wish they knew)
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Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
It corrects the stalling problems that the '99-03 7.3 turbos have under heavy load. Plus it adds a nice turbo whistle. Click on my signature for a sound track. It's the one at the bottom.