I've read a million times stuff like "check ur vacum lines",etc... but I don't know what they are for..
any info would be great!

thx in advance


p.s. : Ive used the search and found nothing

 

They are for making your car run like crap when one (or many) have a leak. Idling is an object of desire.

 

http://auto.howstuffworks.com/engine.htm

Good place to start.

The simple answer: They are little rubber hoses (black stock) that are plumbed to all kinds of engine management accessories that accomplish various tasks.

In modern stock form, the rotary has all kinds of little devices that use vacuum, primarily to clean them up emission wise.

 

Ill read that again.. cause that's like where I started to know sumthing about engines and I don't remember anything about vac lines

 

The main brain (ECU) in the car needs to tell how hard you are hitting the gas, and there is a sensor for that called the Throttle position sensor. But this sensor doesn't tell you what effect this has on the engine... For instance if you're going up hill you can slam the gas but not be going anywhere. The throttle plates are open fully but you're not speeding up. When you open the entrance to a chamber (intake manifold) and there isn't much flow, the pressure inside it drops. Knowing the pressure inside this chamber can help you tune the engine to accelerate quicker. So to measure that pressure, you can drill a hole in the chamber put a line on it (vaccum line) and add a sensor at the end the line that is calibrated to the range of pressures the chamber will experience. That's one reason for a vacuum line.

Let's say you're Mazda and you've got some emissions requirements from "THE MAN". You know that a certain ranges of vacuum and pressure, you're rotary engine runs nastily rich. You can reference the pressure / vacuum and use it to activate different devices mechanical or electrical to cut down on your emissions... things like the Air Control Valve.

But how can you reference these pressures / vacuum? Drill more holes in the chamber and run the lines to where you've got the sensors / devices. So in the end when you've got all these things that are necessary to make the engine run within the U.S. standard all the control devices are connected / activated by a vacuum / pressure line that runs from the manifold to the device.

Here is where the problem lies.... if you have one of these lines pop off or break, the engine will suck air through it. But if the air isn't going through the device that is supposed to be measuring air, how does the fuel system know how much fuel to inject? It doesn't. So that ratio of air to fuel is now upset... ideally it's 14 bits of air to each bit of fuel. If the engine is measuring air from the air flow meter and injecting the perfect amount of fuel for it, you're fine. But when more air enters the whole mixture is off and you could get a poor idle and even slow acceleration...

Ok i'm done.