My truck makes a shhhh sound when I accelerate the air pedal?

Tiny
JOJOS10
  • MEMBER
  • 1995 CHEVROLET S-10
  • 64,000 MILES
I had my catalytic converter checked that's not it, plus my truck jerks if I accelerate to fast also I can press the air pedal all the way down and it wont speed up at all, I checked my transmission, it switch gears my belt is good. So, over all I hear the "sHHHHH" sound only when I accelerate the air pedal, and when I accelerate fast from stop position it wont move fast it will climb RPMS slow.
Sunday, October 7th, 2012 AT 8:59 PM

11 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Sounds like the cat converter is clogged. Have the back pressure checked to verify

Roy
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Sunday, October 7th, 2012 AT 9:49 PM
Tiny
KHLOW2008
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Did you check for trouble codes? Is the Malfunction Indicator Light showing?
Noise described seems to indicate a leak somewhere or clogging in exhaust system.
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Sunday, October 7th, 2012 AT 9:49 PM
Tiny
JOJOS10
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Roy yes it was checked, also, no cel comes on.
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Sunday, October 7th, 2012 AT 10:26 PM
Tiny
ASEMASTER6371
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How was it checked? What was the back pressure measurement?

Roy
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Sunday, October 7th, 2012 AT 10:36 PM
Tiny
JOJOS10
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I saw him put his hand over tail pipe.
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Sunday, October 7th, 2012 AT 11:33 PM
Tiny
ASEMASTER6371
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Thats not a test. It can still pass enough exhaust to feel it but not let the engine breathe.

Thats why you need to measure the back pressure.

Roy
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Sunday, October 7th, 2012 AT 11:36 PM
Tiny
JOJOS10
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  • 10 POSTS
@ Roy I just had my cat converter installed a month ago my engine is good, it never blow black smoke out the tail pipe also, thank you for taking the time to help me with this problem.
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Monday, October 8th, 2012 AT 2:26 AM
Tiny
EVOLVE960
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  • 63 POSTS
Sounds like a gross vacuum leak actually, something intake side or brake booster. Those are the biggest lines you have in the system ( 1/4 ) some larger. Especially if its leaking to the booster that will cause a whole host of issues. If vacuum is dropping in the system it also could be shutting down the fuel pressure regulator which would allow more fuel into the rail under hard acceleration.
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Wednesday, October 10th, 2012 AT 12:37 AM
Tiny
JOJOS10
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  • 10 POSTS
I found out it is the EXHAUST manifold flange gasket. May I ask will this cause all these symptoms?
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+1
Wednesday, October 10th, 2012 AT 1:00 AM
Tiny
KHLOW2008
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  • 41,815 POSTS
Yes, exhaust leaks can cause performance related issues. Have it rectified first.
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Wednesday, October 10th, 2012 AT 1:46 AM
Tiny
MIKE H R
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Check the vacuum line going into the truck. It is by the brake booster. One side goes to the engine and the other to a t with one part going into the firewall. The vacuum line works the heater control. The other side is plugged into a caninster inside the drivers side fender.
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Tuesday, October 16th, 2012 AT 8:31 PM

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