Question about 1991 Pontiac Sunbird

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Replaced brake booster now car idling rough and stalling at low rpms when sitting at lights even if you dont touch brakes

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IT sounds like you have a large vacuum leak. There should have been a hose that plugged into the vacuum booster, check to make sure that it's hooked up on both ends still. Then if that doesn't solve the issue take a look at the new vacuum booster. You may have gotten one with a leak in it. Basically it will be sucking in air somewhere, it's supposed to be sealed. You may hear a whistling sound as it pulls air into the booster. Try that first.

Posted on Nov 12, 2009

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Check vacuum hose for leaks or cracks

Posted on Nov 12, 2009


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1 Answer

'96 Mystique 2.0 trouble with idle. replaced idle mixing valve. I don't get any codes, I have to shift to neutral at a stop sign or light to keep from stalling. It gets real rough almost a lope.

troubles at lights may very well mean a vacuum leak from a faulty brake booster
test by stopping and then applying the park brake and taking your foot of the brake pedal
you can do this test in the garage
start the engine , apply the park brake , place in drive
if it idles alright , put you foot on the brake
if it plays up , replace the brake booster

Jan 24, 2017 | Cars & Trucks

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My brake booster seems to be taking in air, brakes works fine but car idles low and my brake booster going bad

every possibility. If you hear air noise on brake application or the engine stalls with the brakes applied then the booster is suspect and should be replaced.

Feb 10, 2015 | Cars & Trucks

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Stalls stop

IT sounds like a vacuum leak from the brake booster on brake application . Easy test run the car and if it idles ok then put your foot on the brakes and if it stalls it is the booster.

Mar 20, 2014 | 2000 Ford Focus

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Engine runs rough and gets worse when accellerating

Rough idle, stalls or
hesitate on acceleration :
.Spark plug faulty
. High-tension cords faulty
Ignition problems:
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. Incorrect ignition timing
Vacuum leaks:
. PCV valve and line.. .
. EGR line..
. Intake manifold.
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Dec 12, 2013 | 1989 Toyota Camry

1 Answer

Stalls at lights, sounds like it is chugging air like a tractor.

try this simple test
start the car and hold at around 1000 rpms until the engine warms up
now place it in gear with the handbrake on ( don't touch the foot brake
if it is idling at around 800 rpms and is smooth, apply the foot brake
if it plays up , replace the brake booster as there is a vacuum leak upsetting the idle mixture setting
recheck by allowing it idle in neutral with the hand brake on and the apply the foot brake

Feb 28, 2017 | 1995 Nissan 240SX

1 Answer

Idle good when cold, hotter it gets the worst it idles especially when sitting at stop lights

simple test for a vacuum brake booster
star and run the engine at idle without applying the foot brake
if it gets worse when the foot brake is applied , it is a vacuum leak in the booster ( replace the booster )
otherwise check for failed vacuum hoses including under dash control lines , vacuum leak at the manifold or EGR unit

Apr 16, 2017 | Chevrolet Astro Cars & Trucks

1 Answer

Engine idles fine but when you push on the brakes it will surge up about 300 rpms and than starts idling rough and if it is gear it will die.

Is there a hiss under the dash when you step on the brakes? If yes, your booster diaphragm has torn. I have a post here on replacing the booster if that is the problem:

Jun 17, 2011 | 1997 GMC Jimmy

1 Answer

My 95 nissan maxima is idling rough and then stalling when i let off the gas or am stopped at a light or stop sign; i have replaced the coolant temperature sensor, not it. Took it to the nissan dealership...

the problem is fuel related and nowhere else
it indicates a vacuum leak , either at the manifold , brake booster , transmission actuator hose/unit for the transmission or hoses that control under that dash
bad at stopping at light indicates that it is the brake booster
simple test is to put the hand brake on, start the engine and if it idles ok , put your foot on the brake
if still ok move vent controls ,
if with the foot on the brake it plays up , replace the brake booster

Apr 22, 2017 | 1995 Nissan Maxima

1 Answer

I have a 2000 4 cyl. automatic Camry with 52,000. Recently, the car has developed a rough idle and it stalls. This occurs when the engine is hot and I slow the car down at a stop light or it stall as I am...

try disconnecting the hose to the brake booster and plugging it, the take it for a drive, ( you won't have power brakes so do this in a empty area)

Jul 19, 2010 | 1997 Toyota Camry

1 Answer

Brakes go to the floor and the car run rough with...

Sounds like the Brake booster. There is also a valve on the vacuum line going to the booster. Its plastic and can crack and leak.

You can do a water spray test with a pump bottle. Spray the brake booster while the engine runs, spray the vacuum lines and the fittings. When the water is drawn into the engine it will change RPM or stall. The leak is where you sprayed to make the RPM change.

You will need to replace the defective part.

May 17, 2010 | Cars & Trucks

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