My car idle's when I have to brake hard. Does anybody know the reason why car's idle in the first place?

 

 

are you sure you are using the correct term? if an egine doesn't idle it is changing the rpm constantly or is off. describe what you mean by idle.

 

Im sorry what I mean by idle is when the car is not moving say for instance Im at a light waiting for it to change, I can feel the steering wheel shaking.

 

By your definition of idle, I still can't figure out what you're trying to ask in the first post.

Do you mean to say that your car vibrates/shakes alot when you brake hard and also when you're at a stop light?
If so then the braking problem could be caused by bad rotors. If there are uneven spots on the brake rotor thhen when you apply the brake you'll feel the vibrating/pulsing/shaking. Uneven rotors usually cause brake pads to wear away pretty quick. You can feel the vibration in the steering wheel also at a light, but that could be other problems also. For now, look after your brakes and hope this also solves your other problem.

 

i think he's saying that when he is on the brakes and stopped, his idle drops so low as to make the car start shaking. Is that what you meant?

 

[QUOTE]Originally posted by Sudesh
[B]

By your definition of idle, I still can't figure out what you're trying to ask in the first post.

Do you mean to say that your car vibrates/shakes alot when you brake hard and also when you're at a stop light?
If so then the braking problem could be caused by bad rotors. If there are uneven spots on the brake rotor thhen when you apply the brake you'll feel the vibrating/pulsing/shaking. Uneven rotors usually cause brake pads to wear away pretty quick. You can feel the vibration in the steering wheel also at a light, but that could be other problems also. For now, look after your brakes and hope this also solves your other problem.

I don't think it's the rotors because about a month ago I got my brake pads and rotors changed so I don't think that is the problem. Thanks for the help though.

 

Yeah that is exactly what I meant. What can I do to stop that?

 

A rough idle can be caused by many things. When is the last time you had a complete tune up? Has your throttle body/intake ever been cleaned out? Start simple and cheap and hopefully its nothing major.

 

well my haynes book says a bad idle could be:
1. vacuum leak
2. leaking egr valve
3. ail filter clogged
4. fuel pump not delivering sifficient fuel to the fuel injection system
5. leaking head gasket
6. timing belt and/or sprockets worn
7. camshaft lobes worn
8. throttle body ports clogged

could be one of those eight. i'm leaning more to the easier ones like 1, 2, 3, 6, or 8. could be 4 also but it could just be a clogged fuel filter which would probably let the car not rev very high. maybe check those few things out.

 

One of the suggestions that I received was to change the type of gas I put in there I put quicktrip regular he told me to put amoco plus or premium and maybe that should make a difference.

 

It could also be a weak battery or the alternator may be on its last legs. When you're on the brakes, its gonna put more of a load on yoru alternator. Check some of the other electrical components on your car. Put as heavy a load on it as you can and see how much your idle drops. Turn on your air cond, head/fog lights, interior lights, wipers all at once and see how much your idle drops. If this causes a big change in idle position, check your electrical system. If not, then it may be something in your list from earlier...fuel filter or vacuum leak most likely.

In any event, check your tune-up records and see if regular maintenance has been done. If not, it may be a good idea to go ahead and replace the normal tune-up stuff. spark plugs, wires, dist. cap and rotor, fuel filter, etc. Hope this helps.

Kevin

 

If this only happens when you hit the brakes hard you probably have a brake booster going bad. The brake boosters job is to make the brake pedal easier to use with the assistance of vacuum. Try doing this: Disconnect the vacuum line that goes into the brake booster. Make sure you cap the vacuum line with something so it doesn't create a leak. Try hitting the brake pedal again (you'll notice it will be hard as hell) and if the drop in rpms is gone then you have a bad booster. I've had customers whose cars would cut off if they had to hit the brakes hard due to bad boosters.

 

good point. Too bad i wasn't thinking about that!