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Underpowered engine, exhaust smoke concentration how to diag

2014-03-22 14:21      Click:

Q: Underpowered engine, exhaust smoke concentration how to diagnose and exclusion?


A: The lack of engine power, speed uneven rows of thick black smoke in the exhaust pipe phenomenon, there are two: one is the continuous discharge of smoke; another intermittent discharge of smoke, and the engine chattering.


⑴ reason


Lack of engine power and continuous row of black smoke, the engine cylinder majority or all of the cylinders are excessive amount of oil, fuel and air mixture ratio imbalance, severe hypoxia during combustion, diesel combustion is not complete, the suspension of free-shaped carbon element with formed with the discharge gas. If the exhaust pipe is intermittent discharge of smoke and accompanied by "chug" sound, indicating that individual cylinder combustion is incomplete. Summarized as the following reasons:


① improper injection pump debugging, make excessive amount of oil, incomplete combustion.


② poor quality of most jet injector.


③ When the oil is not correct.


④ reduce the intake valve opening height, open delayed, resulting in insufficient intake.


⑤ dirty air filter or air filter is installed incorrectly, so that the air is not smooth.


⑥ turbocharger supercharging performance degradation.


⑦ fuel quality is too poor.


⑵ diagnosis and treatment


When the diagnosis of such a failure, we should start at the most obvious fault features, whether continuous or intermittent discharge of smoke, should comply with this principle.


① If the engine suddenly black smoke, _ but after a period of operation of natural fault disappears, mostly due to poor quality of fuel, due to the impurities in the oil injector clogging caused by poor quality jet exhaust black smoke, running for some After the time is the high pressure oil to wash away impurities, such a failure without treatment.


② If the continuous row of black smoke, consider checking the intake is smooth, whether the intake pipe deformation increased intake resistance. First remove the air filter cover, remove the filter and clean up after the re-test machine maintenance, continue to observe whether the exhaust pipe exhaust smoke. If you smoke significantly reduced, then the air filter is too dirty or installation problems affecting the intake air, should strengthen the intake system maintenance.


③ If the inlet air to flow freely, you should check whether the time the oil is too late, too late to make the supply of fuel into the cylinder combustion was discharged too late to form a smoke.


Most of the injector spray quality ④ serious deterioration, poor fuel atomization, can not meet the needs of the combustion chamber shape, resulting in the formation of combustible mixture difficult part of the fuel is discharged into free carbon. This is also one of the reasons smoke, so the injector should also be checked for repair.


⑤ Check the fuel quality is up to standard, you should use the standard diesel engine to work properly in the ambient temperature in the region.


⑥ Check whether the turbocharger is working properly. When a turbocharger failure, engine intake end of the pressure drop, resulting in compression end temperature and pressure decreased, the impact of jet fuel atomization and combustion temperature.


⑦ If the injection pump repair time is not long, smoky exhaust pipe, lack of motivation, you should consider whether improper fuel injection pump debugging excessive, which should be recalibrated fuel injection pump in a variety of operating conditions amount, to conform to requirements.


⑧ If these were normal, and the engine has been running for a long time, can be considered to check the height and open the valve opening time is correct. Prolonged use of valve train parts can wear normal valve timing and valve lift inaccurate, reduce the intake air, a corresponding increase in the amount of residual gas cylinder, direct impact on fuel combustion.


⑨ For Speed uneven, intermittent exhaust smoke, unable to be used by the engine diagnostic method to check off the oil tank.


When a cylinder off oil, engine speed decreased, reducing smoke, abnormal noise disappears, then the excess amount of oil in the cylinder, the cylinder fuel injection quantity cope check adjustments. If the engine speed changes less, smoke disappears, then the difference between the cylinder injector spray quality, respond to the injector for inspection. If the engine speed remained unchanged, it shows that the cylinder does not work, check the condition of the high-pressure fuel tanks, such as how to cope with the situation, Deputy injection pump plunger, delivery valve pair, fork rod fixed on the fuel adjustment screws (or ring fastening screws) loose, whether the plunger spring break and so on. If you are normal, you should check the work of the injector and the cylinder is a mechanical failure.

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