MOSFET imported original FET

Kaixin micro test

Test - lowercase jpg

Test probe PH-5H

How is the intake manifold vacuum detected?

Diagnosing the EFI engine with a vacuum gauge essentially detects the vacuum of the engine intake manifold.

When detecting the vacuum of the engine intake pipe, the vacuum gauge should be connected to the rear door of the throttle valve. Under normal conditions, the gasoline engine will run at the specified idle speed without load. Remove the air filter and check the reading and indication status of the vacuum gauge. . The operating status of the vacuum gauge in the actual test is as follows (P is the cylinder pressure, Px is the intake manifold vacuum):

(1) Engine sealing performance When the engine is running at a normal state, the gauge of the vacuum gauge should be stable between 64 and 71 kPa (the magnitude of the swing and the speed of the oscillating speed are related to the engine's tightness, air-fuel ratio and ignition performance) . If you suspect that a cylinder is not working properly, you can use the single-cylinder fire-breaking method. After a single-cylinder fire, the drop value of Px should be as large as possible. This is an indicator to judge whether each cylinder works well (ignition, injection, sealing) .

Quickly open and close the throttle valve. If the needle is sensitively oscillated between 6.7-84.6 kPa, it indicates that the Px has better follow-up of the throttle opening change, which means that the sealing performance of each part under various working conditions is good. If the sealing is not good, the Px is lower than the normal value at idle and is obviously unstable. When the throttle is quickly opened, the hands will fall to zero, and the hands will not return to 84.6 kPa after closing the throttle.

In order to verify the sealing performance of each cylinder, the vacuum gauge should be exchanged at the hole of the oil dipstick of the inserted machine, and the pressure in the crankcase should be measured as the negative pressure value; if it is positive, the sealing is not good, or PVC ventilation Asked to be blocked.

(2) What should I do if the ignition timing of the engine is incorrect, the timing of the valve is not correct, and the spark is in a bad state?

When the ignition timing of the engine is incorrect, the timing of the valve is not correct, and the spark is poor, the combustion conditions are deteriorated, the power loss and the rotational speed fluctuate greatly, and the high vacuum is not formed, and the idle speed is unstable and the acceleration is weak.

When the idling is running, the hands swing between 46.7-57 kPa. If the ignition is too early, the hands swing a large amount; otherwise, the swing is small. When the valve timing is wrong, the phenomenon is not the same as the ignition timing, and should be handled separately according to the cause.

(3) What should I do if the engine exhaust system is blocked?

There is a large back pressure when the engine exhaust system is blocked. In the idle state, Px sometimes reaches 53 kPa, but it quickly falls to zero or very low. When the blockage is severe, the gasoline engine can only barely run. At this time, it can be verified by observing the exhaust pipe exhaust state or removing the exhaust pipe operation.