![]() There are several things that can cause stiction of the spool valve. When the FICM commands the injector to open, there can be a delay in the spool valve movement, usually from the spool valve sticking in the bore. Now realize that if the engine is at WOT, this would be 21,000 psi!īut, what is injector stiction and how does it relate to the injector? Injector stiction has to do with the injector spool valve. The pressure of the fuel in the delivery chamber being forced through the tip of the injector nozzle will be 4,200 psi. When the open coil is energized, the high-pressure oil comes into the injector and the piston and plunger move downward. Put it this way: let’s say the engine is at idle and the high-pressure oil is at 600 psi. Do not use anything else or you may suffer injury or death from the high-pressure fuel.) ![]() This cap is made to withstand the high pressures associated with a common-rail system. (A word of caution here: this “cap” is a special tool made by Cummins specifically for this test. Next, I place the cap on the fuel rail where the fuel line was. The only way that you can isolate an individual cylinder is to cut off the supply of fuel - in order to do this in a common-rail system you’ll have to cap it off.įor the Cummins engine, I start with the first cylinder and remove the hard line between the fuel rail and injector. But what if you still can’t determine which one is the problem child? Then you’ll have to dig a little deeper and isolate each cylinder. This type of diagnosis can be very useful in trying to identify which injector may have an external crack. #Drb3 emulator injector kill test cracked#If the injector is cracked externally and producing a smoke wisp, you will be able to smell the hint of diesel fuel in the air. But this wisp should not be confused with blowby, which will be seen also. The wisp of smoke that can sometimes be seen is actually the atomization of fuel being released from the crack. Sometimes, if the injector body is cracked externally, you may be able to notice a small wisp of smoke from the injector. With a light, study the injector body of each cylinder. First remove the valve cover, then crank the engine and let it idle. When the leak down occurs, the engine has to spin over for an excessive period of time in order to re-prime the injection system.Ĭummins recommends a simple visual test to start. #Drb3 emulator injector kill test crack#When the engine is shut down, the crack in the injector’s body will often cause fuel to drain back from the fuel lines and rails back to the tank. In addition, the customer may notice some fuel dilution in the oil by seeing that the oil level is rising on the dipstick. When the body is cracked, the engine will not necessarily produce a miss but will cause other problems, which can be even more difficult to pinpoint.Īlthough the injector body can be cracked, the engine may still run fine but just take an extended period of time to crank. One of the most common failures occurs when an injector body becomes cracked. ![]() However, injectors can fail in ways other than becoming just worn out or tired. In cases such as these, the scan tool generally will pinpoint the cylinder with the contribution problem. Like anything else, injectors can get tired and become weak over time.Įven though they are electronic, sometimes the mechanical components inside the injector may also become worn, cease to function properly and even fail. The misfire is generally associated with a loss of power and no unusual smoke. The most common injector issue is when the engine produces a cylinder misfire. ![]() But some problems may be tougher than your customer - or you - think. The good thing about electronic diesels is that the technician can link up with a scan tool to analyze data in order to try to pinpoint problems. Owners often think that because diesel engines are now computer-controlled, the technician should be able to hook up a scan tool and immediately see what is going on. A phrase that I often hear from customers is, “This is a diesel engine the problem should be easy to diagnose.” The right part about that statement is that the customer realizes that he has a diesel engine.Ĭertainly, there are some common repairs needed on specific engines that are easy to do, but that doesn’t mean everything else will be easy to diagnose.
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