Sounds like an exhaust leak… but acts like a vacuum leak. Whatever could it be?
So I am running out of ideas, and thought perhaps someone here might clue me into a new direction or a place to look.
I have a 06 LS2 CTS-V nearing 100k miles. I have had the car for 8 years. In the last 6 months or so an intermittent noise keeps appearing when:
- the engine is cold and running up to operating temps.
- When you lift the throttle and let the car coast while the engine rpm winds down (noise diminishes with rpm and is 100% dependent on engine RPM)
The noise is greatly reduced or disappears when the car is warmed up. It sounds like an exhaust leak but only makes noise when the car is moving, in gear, and your foot is removed from the throttle… the second you apply the gas (even just to maintain speed) the noise immediately cuts out. It is engine RPM specific and really does sound like an exhaust leak… its just not characteristic of one because the noise is not continuous like a exhaust leak.
It also sounds like it is coming from the passenger side of the motor… I could be wrong, but I would bet money on it.
So let me just say that I have a custom exhaust, I have taken it apart many times looking for the culprit, and have no reason to suspect it. I am running factory manifolds, hi- flow cats, and a corsa system. I have ran my hands down the entire exhaust system looking and listening for leaks with the car running… taken the system apart and tested for leaks… even welded the whole corsa system together. Unless it’s the manifolds under that heat shield… no way it is the problem.
To me it sounds like an exhaust leak but behaves like a vacuum leak of some sort. It is crazy that it cuts out as soon as you lightly touch the gas pedal and only happens while in motion and when you take your foot off the pedal
Any ideas? Thanks for taking the time to read this the whole way through.
So I am running out of ideas, and thought perhaps someone here might clue me into a new direction or a place to look.
I have a 06 LS2 CTS-V nearing 100k miles. I have had the car for 8 years. In the last 6 months or so an intermittent noise keeps appearing when:
- the engine is cold and running up to operating temps.
- When you lift the throttle and let the car coast while the engine rpm winds down (noise diminishes with rpm and is 100% dependent on engine RPM)
The noise is greatly reduced or disappears when the car is warmed up. It sounds like an exhaust leak but only makes noise when the car is moving, in gear, and your foot is removed from the throttle… the second you apply the gas (even just to maintain speed) the noise immediately cuts out. It is engine RPM specific and really does sound like an exhaust leak… its just not characteristic of one because the noise is not continuous like a exhaust leak.
It also sounds like it is coming from the passenger side of the motor… I could be wrong, but I would bet money on it.
So let me just say that I have a custom exhaust, I have taken it apart many times looking for the culprit, and have no reason to suspect it. I am running factory manifolds, hi- flow cats, and a corsa system. I have ran my hands down the entire exhaust system looking and listening for leaks with the car running… taken the system apart and tested for leaks… even welded the whole corsa system together. Unless it’s the manifolds under that heat shield… no way it is the problem.
To me it sounds like an exhaust leak but behaves like a vacuum leak of some sort. It is crazy that it cuts out as soon as you lightly touch the gas pedal and only happens while in motion and when you take your foot off the pedal
Any ideas? Thanks for taking the time to read this the whole way through.
