Vaccum issues

[ddt4436]

I have a 90 mustang gt all stock except eddy intake. It idles really bad to the point of it cutting off along with not staying crunk at all. I can hear air being sucked from behind my brake booster under the inside of the dash and the brakes ar horrible. Can there be a possible vacuum leak under there causing it to horrible idling and poor driveability? Please Help!

 

[irish]

I'm not sure what "crunk" is but if you can hear a vacumn leak, then you need to find out what/where it is leaking from and yes it will make your car run badly.

Matt

 

[ddt4436]

My bad, crunk=running. My question is does the brake booster need changed or is there a vacuum line up in there under the dash? I never had a mustang to hiss from under the dash interior by the brake booster. Any more suggestions?

 

[jrichker]

If you hear the vacuum inside the car, the booster is suspect. However, I recommend replacing the rubber grommet that the brake booster check valve mounts in. The brake booster check valve is the metal fitting that the large vacuum hose connects to. The rubber grommets crack and harden with age and heat, so they often leak.

The other source of interior cabin vacuum leaks is the HVAC controls that control airflow for the heating and cooling. If your HVAC works OK, then this is not a suspect.

 

[ddt4436]

Thanks alot J! That made a lot of sense. I'll check that today.

 

[ddt4436]

Ok here's what happened. I took the large hose off the brake booster and plugged it and the car idled perfect. Hooked it back up and horrible idle again. I'm trying to figure if the problem can be fixed without removing the booster as that is alot of work.lol. I did check the grommet and it looked cracked but I don't know if that crack is pulling in all that free air coming into the booster.

 

[jrichker]

Replace the rubber grommet. If you get a remaufactured booster, the gromment may not come with the new part. If the grommet fixes the problem, you saved some $$$, some sweat and skinned knucles.