Injector total oil return test
Detection Tool
Fuel return hose (part number 3164618)
2 open wrenches (17# and 19#)
Measuring cylinder (100ml range)
Torque wrench (with 22# fork head)
INLINE (INSITE is a kind)
Computer with INSITE service software
Barrels for collecting fuel
Steps
Install the oil return hose
Use a wrench (19#) to remove the hollow bolt connecting the oil return pipe of the injector. Install the quick connector for the oil return test of the injector and connect the oil return hose. Put the other end of the fuel return hose into the barrel.
Connect INLINE
Open the INLINE interface in front of the passenger seat, connect INLINE (note the connection direction), and connect the other end of INLINE to the computer.
Start the engine to test
Turn on the vehicle power and turn the car key to the ON position;
Open the INSITE software on the computer, and click on the software interface to connect to ECM;
Put the other end of the fuel injector oil return hose into the barrel;
Start the engine and keep the engine running at idle speed; when the return oil from the fuel injector flows into the barrel, use the INSITE service software to perform a high-pressure leak test for 1 minute, and insert the return hose into the measuring cylinder to measure the fuel return volume of the fuel injector.
Result identification
Description
If the fuel return volume of the fuel injector exceeds 70ml, a cylinder break test is required to determine the damaged or worn fuel injector;
If the oil return volume does not exceed 70ml, it is proved that the oil return volume of the injector is qualified. After the test is completed, remove all tools and restore them to the original state.
Broken cylinder inspection
Cylinder broken inspection is to stop any cylinder of the engine through manual control when the engine is idling, and analyze whether the working performance of the cylinder is normal by observing whether the working state of the engine has changed.
After the work of the cylinder is interrupted, if the engine speed and smoothness change greatly, it means that the components of the cylinder are working normally. If there is no change or the change is small, it can be concluded that there is a problem with the related parts of the cylinder.
The operation of the engine broken cylinder inspection
In the process of automobile maintenance, in order to accurately determine which cylinder the engine failure occurs, it is often rumored that the method of “cylinder broken” test is used to narrow the scope of failure inspection. The “cylinder cut” test is divided into three forms: cut off oil, cut off gas and cut off fire. Their essence is to temporarily stop the work of a certain cylinder, and then observe whether the operation of the engine changes to judge the working condition of the cylinder.
Oil cut inspection method
When a diesel engine fails, we often use the method of loosening the beginning (injection pump end) or the end (injector end) of a certain cylinder’s high-pressure fuel pipe when the engine is on fire. law).
Carrying out the “fuel cut” test on diesel engines, usually by unscrewing the connection of the high-pressure fuel pipe to the injector, cutting off the oil path of the cylinder, and then observing the operating conditions of the diesel engine. If the operating sound of the diesel engine changes significantly, it means that this cylinder It works normally; if the speed of the diesel engine does not change, it means that the cylinder is not working well.
For example, if a diesel engine “knocks” or emits black smoke, the “fuel cut” test can be used to cut off the fuel supply to a certain cylinder. If the failure phenomenon disappears or alleviates, the failure is in this cylinder; if the failure phenomenon does not change, it indicates The fault is not in this cylinder.
The “fuel cut-off” test method cannot be used for electronically controlled high-pressure common rail diesel engines, because once the high-pressure fuel pipe joints on the injectors of the common rail diesel engines are loosened, the common rail diesel engine will go out immediately. The reason is that loosening the high pressure oil pipe joint on any injector will not be able to establish the common rail oil pressure of the electronically controlled diesel engine.
For electronically controlled high-pressure common rail diesel engines, a fault diagnosis instrument can be used to lock the fuel injection system of the diesel engine for a single cylinder, that is, the diagnosis instrument is used to cut off the fuel supply of the injector cylinder by cylinder. At the moment when the fuel supply of a certain cylinder is cut off and the fuel supply is restored, if the working condition of the diesel engine does not change, it means that the cylinder is working abnormally.
Gas test
Taking the “gasp” sound in the radiator as an example, the method of shutting off the air cylinder by cylinder can be used for troubleshooting. For a YC6105 diesel engine, there is an obvious “gasp” sound in the radiator when it is working, which is similar to the “boiler boiling” phenomenon, which is more obvious when accelerating. At this time, the coolant temperature is only 70T. Checking the cylinder head, cylinder head gasket, coolant pump and thermostat, no abnormalities were found.
So disassemble the intake manifold, let the engine run at idle speed, find a whole piece of cotton yarn, and moisten the cotton yarn with water (to prevent dripping), and then cover the air inlets of each cylinder one by one to “cut off the air” cylinder by cylinder. At the same time, ask another person to observe the fluctuation of the coolant level in the radiator. When the air intake n of the fourth cylinder is covered, the coolant level in the radiator drops significantly, indicating that the source of the “gasp” sound is in the first place. 4 cylinders (this greatly reduces the scope of troubleshooting). Pulling out the cylinder liner of cylinder 4 with a puller, it was found that there was an imperceptible transverse crack in the middle of the cylinder liner. After replacing the cylinder liner of the 4th cylinder, the phenomenon of “gasp” in the radiator did not exist.
Fire and power failure inspection method
“Misfire” test is usually to cut off the flashover of a spark plug in a cylinder of a gasoline engine. When the gasoline engine runs at a certain stable speed, its power and the speed reach a balance. When one of the cylinders stops working, the total power is reduced, and the engine speed drops accordingly to achieve a new balance. If the working capacity of each cylinder of the gasoline engine is balanced, the amplitude of the speed drop after each cylinder stops working should be basically the same, otherwise, a larger speed difference will be produced.
The maintenance personnel usually measure the “single-cylinder speed drop”, which is to judge the working condition of each cylinder by detecting the speed drop value of each cylinder of the gasoline engine before and after “failure”. After a certain cylinder is “frozen”, if the speed of the gasoline engine drops significantly, it means that the cylinder is working well; if the speed of the gasoline engine drops very little, it means that the cylinder is not working well; if the speed of each cylinder drops basically The same indicates that the working uniformity of each cylinder of the tested gasoline engine is good.
