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Discussion Starter · #1 ·
While accelerating or travelling at a steady pace, I hear a "hiss" from the front of the vehicle as I pass 2K rpms or as a ride steady at 2K rpms. I have taken it in to a dealer and they thought it was an exhaust issue but determined it was not. They were unable to find a problem.

Any Help or Ideas would be appreciated!?!?!?!

Thanks
Michael
 

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I have the exact same problem, i was under the impression that it was an exhaust leak also, but then i realized that most exhaust leaks are not rpm-specific usually. i asked my auto shop teacher about it and he thinks its a compression issue of some sort in a cylinder. Ill try and keep you updated.
 

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I had a hissing that I could hear when the engine was running, but was only really obvious with the bonnet up and listening to the engine.

Mine turned out to be a loose vacuum hose just below the inlet manifold which could be seen between two of the manifold tracts. I think it is an air pipe which goes to the ASV. Mine had just had the injectors cleaned and wasn't starting as well as it did before.

The engine will run and mine did not throw up a CEL. The system just adapted to it, i.e. the ICV will change the airflow to maintain idle.

This is the best case scenario, just a pipe connection.

Also check for the integrity of other pipes.

At 2,000 the vacuum will be the maximum and at higher speeds, the throttle will be open more (Less restriction) so flow through any vacuum leak will be reduced.

Mine was noticeable on cold start-up. (1,500 rpm).

I think mine has still got an air leak into the fuel lines now because mine takes a while to start (time for the fuel pressure build up), which wasn't a problem before.
 

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Another thing, valve clearances might need checking.
 
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