Hissing sound when accelerating
 

I have an 06 2.4 5 speed, recently a new noise appeared, it makes a hissing sound when I am accelerating, it gets louder when I accelerated harder. Is there a cure for this, and what is it? There are no engine warning lights on, how can it be diagnosed? It has not changed the performance or mileage. Anyone else out there had this annoyance?

Thanks,

Len

There may be three versions of the noise.
1. Aerodynamic noise. Eg. Aerodynamic noise arises from not tightly closed window. If you have recently installed the equipment on the car (a new antenna or fog lights). If the car appeared little damage (a crack on the bumper, chips on the glass or the edge of the protection of the wings was released). All these reasons may give a hissing sound. Inspection of your car carefully. Do not forget to view from the bottom and under the wings.
2. Hissing sound give the tire. If you recently replaced the tires - maybe that's the reason for the noise. Once I was two days searching for the cause of his noise. You'll laugh. The reason: a new asphalt surface. Municipal authorities were simply repaired the road from my house to my office. Tires hummed on smooth new surface. And I have already set aside money on a new wheel hub bearing.
3. Technical reasons. Hissing sound may give ventilation and air conditioning compartment. Verify this simple: redirect the air flow first to the window, then the legs. Let us see if the character does not change the noise. Then just turn off air cooling. Hissing to stop. Hissing sound may occur in the air line air filter engine. There easily fall fallen leaves from the road. Remove the cover of the engine, dismount the tube and clean it. This is a good reason to replace the engine air filter, then do not climb up there again in the future. This simple operation does not take long and complex instruments.
My opinion is. If the hiss - then the problem is in the air currents. Weak belts usually whistle. Killed bearings are buzzing like an airplane or a howl. Air - sizzles. Search. Good luck.

Try check out the Flex pipe for a small crack. A muffler store can possibly do the inspection. Our HHR had the same syptoms you are describing. We found out from the muffler shop that this repair would be covered under the federal emissions warrenty (80k miles) being that the flex pipe was attached to/ part of the cataletic (sp) converter. The dealership took care of the problem and our HHR is once again happy, as are us.

I am having the same issues... A loud hiss that can be heard over the radio but only occurs during acceleration. MPG has dropped considerably since the problem started... from 25.4 to 23.5.

I dropped of the my vehicle at the dealership on Monday and Wednesday afternoon they called to tell me that they couldn't find anything. It was the end of my work day and I couldn't leave my vehicle with them any longer so I said that I would bring it back. I pointed out the noise to the service rep and she acknowledged the issue and said to keep an eye on it for the next couple of weeks.

Looks like I might need a second opinion, or I'll need to start searching for cracks.

I had the same hiss from my 06 when accelerating. I noticed there is a weep hole on the bottom of the muffler that had exhaust blowing out of it. I suspect the noise is due to that leak.

The problem was found to be a cracked exhaust flex pipe, replaced, back to normal.