Break booster fail, caused other issues with vehicle as well. Strange idle etc.

[Astrand1]

Hey everyone I just had the break booster recall performed on the 2012 CX-9 with 75,000 miles. I was driving last week and suddenly lost break power, you'll know because your driving without power breaks and it requires you to put a lot of weight into the peddle. I was able to apply additional pressure to the system and stop the car but it was a bit scary. Here are some things I want to share that I wish I would have known previously....

1.) When pressing the break I was getting a hissing sound a few months ago, it was intermittent and sounded like it was coming from the engine area. This was due to a vacuum leak in the break system and the start of the failure it seems

2.) I started to get strange idling. Right around the time of the failure I noticed it would start weird and idle rough on occasion when breaking and coming to a stop. Right at the time of the failure; two or three times My tack would jump to 3500 or 4000 rpm when the vehicle would go from breaking to park and then settle back down. In some instances The tack was jumping and the car would almost stall when the vehicle was stopped in-gear (waiting for a stoplight for example)

Seems strange but since I've fixed the break booster this hasn't happened. Vehicle systems are tied together and when one is under strain others are effected. I was worried I was having other sensor issues with fuel and air but since break boost replacement my car has been running like new.

Hope this helps

 

[Anchorman]

Very often, when a car is about to give a problem it will tell you. It's about listening, seeing, smelling and feeling. If you had the car all that time and all of a sudden you become aware that something is different with the BRAKES, why did you wait until it failed altogether? You could have killed somebody.

 

[Astrand1]

Very often, when a car is about to give a problem it will tell you. It's about listening, seeing, smelling and feeling. If you had the car all that time and all of a sudden you become aware that something is different with the BRAKES, why did you wait until it failed altogether? You could have killed somebody.

There wasn't anything wrong with the breaks as far as I could tell through every day operation. Also I had the vehicle at the dealer less than a month ago on a service recall for the control arms, they did a full inspection and found nothing. If you read the post; I was getting a intermittent hissing sound. Also; it sounded like a A/C compressor basically. The breaks were functioning fine, their wasn't any sort of CEL.

You could have killed somebody.....thanks pal

 

[WilDriveAnywher]

Hi Astrand1 - Great to see another with a CX-9 - I've also got a 2012 which just went over 40 K mikes - I can't find any info about a "break booster recall" and I just had a dealer print their history sheet on our car, I'm asking because ..
1 - My wife drives the car and she could not eal with a brake failure (we live on top of a hill at the end of 1 mile dead end road uphill, aggressice slope & very steep driveway.
2.- Bringing car into dealer end of next week to get recall work done on lower control arms and potential transfer case leak/rapid oil deterioration, so would like to get it addressed at same time.
Also - our front pads are good but the front rotors are heavily slotted so getting brake pulsing

 

[cbuechlein]

Hey everyone I just had the break booster recall performed on the 2012 CX-9 with 75,000 miles. I was driving last week and suddenly lost break power, you'll know because your driving without power breaks and it requires you to put a lot of weight into the peddle. I was able to apply additional pressure to the system and stop the car but it was a bit scary. Here are some things I want to share that I wish I would have known previously....

1.) When pressing the break I was getting a hissing sound a few months ago, it was intermittent and sounded like it was coming from the engine area. This was due to a vacuum leak in the break system and the start of the failure it seems

2.) I started to get strange idling. Right around the time of the failure I noticed it would start weird and idle rough on occasion when breaking and coming to a stop. Right at the time of the failure; two or three times My tack would jump to 3500 or 4000 rpm when the vehicle would go from breaking to park and then settle back down. In some instances The tack was jumping and the car would almost stall when the vehicle was stopped in-gear (waiting for a stoplight for example)

Seems strange but since I've fixed the break booster this hasn't happened. Vehicle systems are tied together and when one is under strain others are effected. I was worried I was having other sensor issues with fuel and air but since break boost replacement my car has been running like new.

Hope this helps

The tach jumping up and down and the odd idle was related to the brake booster because a booster uses engine vacuum to provide brake assist. The his you heard was essentially a big vacuum leak because the diaphragm in the booster was torn. CX-9s use mass air flow sensors that require an air that pass them stay there and no other air come in. When you used your brakes you were letting in unmetered air so the computer was trying to compensate.

BTW it's brake not break.

 

[eskimo0101]

I guess in his case the brake did break though.