My car normally idles at around 1100 RPMs, sometimes when I first start it, and begin to drive, it will just stall out on me. It will do this regaurdless of wether the car is warm or cold, being started for a few seconts, or a few minutes. For the first 1 minute of driving, the RPM,s will just drop down, and it will stall, unless you push the gas to the floor to keep it running. After a while though, it works just fine. When it stalls, the brake pedal locks up, so that you cannot stop without downshifting or using the emergency brake. When it does stall, it needs to be cranked for about 4-7secs before it will start back up, which is significantly more than normal. Also, when I'm driving sometimes teh car will feel like it is hesitating, the throtle isn't really responsive, and you can feel the car shake a bit, and hear it in the exhaust. Anyone have ideas? (somthing is also beeping once every minute or so under the dash, factory alarm?, could that be causing this?)

 

Pyro,

I'm guessing that the brake pedal does not truly "lock up", but that you lose all vacuum assist from the power brake booster, requiring an excessive amount of force to be applied to the brake pedal to stop the vehicle.

Your high idle, lack of brake assist, and stalling are indicative of a vacuum leak. If the brake booster is losing all vacuum, the engine would have to crank a long time, run poorly on startup, and have little power.

Try removing the vacuum hose for the brake booster and capping the hose fitting on the manifold. Then start your engine and see if the symptoms are gone. If that solves the hard starting and poor idle, you need to check into the brake booster. You may only have a failed check valve (easy to replace), or the booster shell itself may be corroded through and leaking out all vacuum, or the booster valving/diaphragm may be damaged (not as easy to replace).

HINT: It usually helps to add information about the vehicle, such as model, engine type, and fuel system type.

 

It is a 91 RS v6 3.1L, no idea about the fuel system.
Your right about the brake pedal, I just noticed today that it does work somewhat. Really have to push it down just to get a little braking in. When the car is shut off, if you pump the brake pedal, it will go down once fine, then be a little hard, then be really difficult to get down. I would try your idea about plugging it, the only thing is that it does this at random times, usually only after ive been driving 7 miles or so, so I cannot really go driving around without brakes to find out. When I bought the car, I drove it, it didn't have this problem. Then in a few weeks, this developed, lasted a few weeks, got really bad, then went away. Now after ive been rear ended it came back.

 

You shouldn't have to drive it to determine if the idle speed and quality improves after capping the booster vacuum line.

 

Yeah, I actually realized that today, that the idle should come down with it capped. Now I just have to figure out how exactley to do that. I have a hayes (is that how its spelled?) repair manual on the way so I have some referance when doing my brakes, would somthing like location of the vaccum line be in there?

 

Just follow the large vacuum hose from the power brake booster to where it connects to the engine. Disconnect the hose from the engine and cap the fitting or place a piece of electrical tape over it.

 

Ok, here is one for you. There is not vacuum to the brake booster. I cannot find any line attached to the booster. I did hoever find a line comming off the engine which is capped, and was in with some wires on the brake booster. Should I replace this hose, then reattach?

 

Ok, everyone here can smack me and call me stupid. The vacuum line is connected to the booster. There is still another line that is plugged up right next to the booster. Looks like its going to be hard to get in there to plug up the hole to see if thats whats wrong.

 

Pyro,

You can carefully remove the vacuum line from the brake booster (try not to break the plastic check valve) and cap it there. Of course, that won't do anything to test whether the hose itself is leaking, so it would be best to follow the hose to the intake and cap the fitting there.

As for the other hoses, there shoudl be a vacuum hose routing label on the underside of your hood. Your "mystery" hose should be identified there.

 

There is no such diagram under the hood that I can find, I will take another look for it though. I capped the vaccum hose at the intake, and it didn't lower the idle.

 

Ok, i'm pretty sure the mystery hose isn't a vaccum. I followed it down as far as I could. It goes down, behind the engine, and I cannot see any end to it, or get my hand far enough down to feel where it ends.

 

The Firebirds I've seen all have the label affixed to the underside of the hood, not on the top of the radiator support. It should be just opposite the VECI label.

 

Dunno, the sticker is gone. Its a camaro not a firebird by the way. Any place online to find the diagram, or should I got to a chevy dealer and ask if there is any way to get one?

 

Hope you don't mind me jumping in here, but I was intrigued to know if you got the tick over revs to come down yet. The symptoms are for air getting in.

You can always try covering any suspect opennings with you finger to see if the revs come down. Just keep away from the fan and hot bits.

 

Pyro...we should be able to ID it if you can get a photo of your engine bay...or maybe describe it a tad more. And it's funny..I don't have the vaccum line label either. Mine's a 91 RS. I gotta use my Haynes, and even then I can't find a decent diagram...I just look around and pick them off one by one. If you have a major vacuum leak, your car will die..but if it's a leak from a smaller hose, your idle will actually increase because the Manifold Air Pressure sensor detects the drop in vacuum and causes the computer to raise idle and dump fuel I believe to try to fix itself.

 

When you get a big vacum leak, it is just like the throttle butterfly being held open, and at tick over it doesn't need much gas, so the revs will go up.

 

If you have a large line just hanging at the left side of the engine, it could be part of the air injection system.