Q: Engine power, how to diagnose and exclude the exhaust of thick black smoke?
A: The engine power is insufficient, uneven speed, the exhaust pipe exhaust thick black smoke of two phenomena: one is continuous black smoke; the other is intermittent black smoke, and the engine shaking vibration.
(1) Cause
Engine power and continuous black smoke, is the engine most cylinders or all cylinders are too much fuel supply, fuel and air mixing ratio is out of balance, serious lack of oxygen combustion, diesel combustion is incomplete, suspended free carbon elements with the exhaust gas and the formation. If the exhaust pipe is intermittent black smoke, and accompanied by sound, indicating that the individual cylinder combustion is incomplete. The reasons are summarized as follows.
① Injector pump is not properly tuned, so that the amount of oil supply is too much, incomplete combustion.
② Most of the injector injection quality is poor.
③ oil supply is not at the right time.
④ Intake valve opening height is reduced, opening time is delayed, resulting in insufficient air intake.
⑤ The air filter element is too dirty or the air filter is installed incorrectly, making the air not smooth.
⑥ The supercharger’s boosting efficiency decreases.
(7) The fuel quality is too poor.
(2) Diagnosis and treatment method
Diagnosis of this kind of fault, should start from the most obvious characteristics of the fault, whether it is continuous or intermittent black smoke, should follow this principle.
① If the engine suddenly black smoke, _ but after running for a period of time the fault disappears naturally, it is mostly due to poor fuel quality, due to impurities in the oil blocking the injector to poor injection quality, black smoke exhaust, after running for a period of time by the high-pressure oil impurities flushed out, this fault does not need to deal with.
② If continuous black smoke, consider checking whether the air intake is smooth, whether the air intake tube deformation increases the air intake resistance. First remove the air filter cover, remove the filter element and clean up after maintenance to retry the machine, observe whether the exhaust pipe still continue to exhaust black smoke. If the smoke emission is significantly reduced, it means that the air filter is too dirty or installation problems, affecting the air intake, should strengthen the maintenance of the air intake system.
③ If the intake airflow is smooth, you should check whether the fuel supply time is too late, the fuel supply will be too late to enter the cylinder of the fuel is not fully burned and the formation of black smoke.
Most of the injector injection quality seriously deteriorated, poor fuel atomization, can not adapt to the needs of the shape of the combustion chamber, resulting in the formation of combustible mixture is difficult, part of the fuel into free carbon was discharged. This is also one of the causes of black smoke, so the injectors should also be checked and repaired.
⑤ Check whether the quality of the fuel is up to standard, and should use the standard diesel fuel that meets the normal operation of the engine under the ambient temperature in the region.
⑥ Check whether the supercharger is working properly. When the supercharger fails, the pressure at the end of the engine intake drops, resulting in the end of compression temperature and pressure drop, affecting the fuel injection atomization and combustion temperature.
⑦ If the injection pump maintenance time is not long, the exhaust pipe exhaust smoke, power is not enough, it should be considered whether the injection pump is not properly tuned so that the amount of oil supply is too much, which should be recalibrated injection pump in a variety of working conditions of the amount of oil supply, so that it conforms to the provisions.
⑧ If the above are normal, and the engine has been running for a long time, you can consider checking the valve opening height and opening time is correct. Long time use can make the valve transmission parts wear, the normal distribution phase and valve lift is out of alignment, the intake volume is reduced, the amount of residual exhaust gas in the cylinder correspondingly increased, directly affecting the full combustion of fuel.
⑨ For uneven speed, intermittent black smoke, engine powerlessness diagnosis can be used to check the cylinder-by-cylinder oil cut-off method.
When a cylinder cut off, the engine speed is obviously reduced, black smoke is reduced, the noise also disappeared, it means that the cylinder oil supply is too much, the cylinder injection should be checked and adjusted. If the engine speed change is small, black smoke disappears, it means that the cylinder injector spray quality is poor, the injector should be inspected and repaired. If the engine speed is still no change, it means that the cylinder does not work, should check the cylinder of the high pressure oil supply, such as the injection pump plunger vice, oil valve vice how to match, pull the fork in the oil volume adjustment lever on the set screw (or tine ring fastening screw) has not loosened, the plunger spring has not broken. If all normal, should check the work of the injector and the cylinder whether there is mechanical failure.