Table of Contents
Why do direct injection engines have vacuum pumps?
Vacuum pumps are used in those motor vehicles for which the necessary vacuum cannot be generated in the intake manifold. These are direct injection engines, turbo engines and engines with variable valve timing, for example. The increasing number of pneumatic actuators can also render the use of a vacuum pump necessary.
What do vacuum lines do?
Vacuum lines connect the primary source of engine vacuum (the area in the air flow path that is ‘after’ the throttle control that regulates how much air is allowed to enter the engine and the point where the air enters the cylinder head(s) ) to wherever a vacuum reference is needed such as an accessory or an engine …
What is ported vacuum?
Ported vacuum is vacuum that is low at idle and increases as you give it gas. Attached to your distributor it will cause the vacuum advance to move quickly to increase performance and drop off when you let off on the gas for a smoother idle.
What causes low vacuum in an engine?
Low vacuum can be caused by low compression, intake leak or tight valves. The gauge needle bounces around a lot-uneven compression if the vacuum reading fluctuates within the normal range.
How does vacuum pump work?
Vacuum pumps essentially move gas molecules from one region to the next to create a vacuum by changing high and low-pressure states. As molecules are removed from the vacuum space, it becomes exponentially harder to remove additional ones, thus increasing the vacuum power required.
What are the functions of a ported vacuum?
So, ported vacuum is used to control vehicle systems, in relation to, engine load. As a result, these include old-fashioned distributor vacuum advance diaphragms and carburetor assist devices. They also include many emissions control devices and transmission shift points.
Is there a vacuum at the throttle plate?
But, there is no significant vacuum at a port ahead of the throttle plate, when the throttle is closed. Vacuum appears at such a port, only when the throttle opens. Consequently, many vehicle systems need a steady supply of low-pressure air under all engine operating conditions.
Where is the fuel injector located in the intake manifold?
Note that the fuel injector is located closely to the intake valve – this is typical of multi-point injection systems Multi-point injection injects fuel into the intake ports just upstream of each cylinder’s intake valve, rather than at a central point within an intake manifold.
Where do you measure vacuum in an engine?
Remember that engine vacuum is just air pressure, lower than atmospheric pressure. So, the starting point to evaluate engine vacuum is, at the intake manifold. When you connect a gauge to a port on the intake; you’re measuring manifold vacuum. To clarify, vacuum drawn from an opening; ahead of the throttle is called, ported vacuum.