I have a 04 supercharged monte carlo ss. It starts fine everytime and seems to idle fairly smooth. But whenever my foot is not on the break i hear a hissing noise like some kind of air leak, whenever i touch the break it stops. Also sometimes when I am slowing down the car stalls and leaves me with no breaks or steering or anything (not a very fun problem at a busy intersection). It only happens when I am slowing down. This same thing happened before (lacking the hissing noise) and I had my MAF sensor replaced. It seemed to be fixed but now it is starting to do it again and getting progressively worse... Are these symptoms of another bad MAF sensor or is there something else that may be wrong?

Thanks for any help you can give!

 

..Hi Cstruthers, and Welcome to the Monte Carlo Family.
Sorry to read that you are having problems with your Monte : (

How many miles on your Monte Carlo ?
Are you getting a check engine light ?
What mod's have you done ?
What service or parts have been replaced ?
The above answers will help our expert tech member's when they read about your problem(s).

* Have you checked everything in your engine compartment for a lose connections ? Is your brake fluid full ?
Can you hear the hiss when engine is @ idle with your hood up and listening ?
Please post more information, because it's sometimes very difficult to help by just the written words that we read...
Look forward to your answers, and keep checking back to see `if one of our expert tech member's can assist...Good Luck...
Oh, when you find the problem, please post what it was...

 

Its got 106k miles on it.
No check engine light (it has never come on so idk if it even works).
No mods
There have been some parts replaced but not sure what was replaced, the car belonged to a mechanic friend of mine and he replace some stuff but no aftermarket parts, all replacements from other montes. Most recently the MAF sensor.

I have felt around all the connections and cant seem to feel and air leaking out or any loose hoses. When in idle with the hood up I can tell that the hiss is coming from the top right portion, right arounf where the break fluid is located (and yes it is full) but i felt around and cant feel any kind of air leak of any kind.

The hiss may be a different problem than the stalling altogether because it didnt make that noise the first time it started stalling.

 

..Thanks for your update & additional infor...
Check back on your thread & see what our other member's post on your problem....(Is your mechanic still your `friend ?)
Have you contacted him ?
Found the below link on hissing...Check it out ~> Good Luck
http://www.automotivehelper.com/topic556790.htm

 

Well he actually replaced the MAF sensor the first time that the car started stalling and that fixed it for a month or so and then it slowly started back again and is now happening more frequently (just like it did before). I dont live where I used to anymore but I will probably venture back there if i cant fix the problem myself.

 

Well the hissing noise indicates a vacuum leak, which could make your car cut off while coasting. Another thing to consider is the MAF could be going bad again, I'm on my 3rd MAF sensor with this motor. Lastly, it could be your crankshaft position sensor going bad.

 

..Thanks `John, for your post & your help to one of our new member's.

Has any other member had the above posted problem with their SuperCharged Monte Carlo ? If so ?, please post.....Thanks

 

Im just throwing this out there, but since it happens mostly when slowing down, with your foot on the brake, and there is a hissing near the brake booster, could it be a ruptured diaphragm in your brake booster?

 

^Sounds like the problem to me.

This would cause a large vacuum leak, that could leak to erratic stalling and idling issues.

 

Hmm that sounds like it could be it... how would I go about checking for that?