How To Accurately Locate The Fault Point When Accelerating Jitter

Troubleshooting

Step 1: first read the fault code with the decoder to show that the system is normal.
Step 2: because it is a cold start and cannot accelerate, there is acceleration jitter. It is suspected that the accelerator pedal is abnormal, so read the data flow, step on the accelerator in situ, check the accelerator pedal voltage, and find that the two groups of voltage values are normal.
Step 3: at this time, some people suspect that the cold start preheating system has a error, but if the preheating system has a error, most of them will report a error code, which is not considered in this direction. However, there is a question about another phenomenon.

Step 4: think carefully. If the value of the water temperature sensor is not allowed to jump, it may really lead to problems in this cold start, affecting fuel injection and so on! So check the water temperature sensor harness and check the data flow. No problem is found.
Step 5: what else is the acceleration exception related to? Oil line! Therefore, the oil circuit was checked. Since no problems related to rail pressure were reported, it would not take time and effort to check step by step. Directly open the data flow to check the trigger current of the oil metering unit, and there was no abnormality.
Step 6: if there is no error in the oil circuit and the trigger current is normal, there is basically no possibility of problems in the oil circuit. However, the fuel injector can not be ignored, so first check whether the fuel injector is powered on, use the test lamp to measure, and all four fuel injectors are powered on.
Step 7: in order to further check the fuel injector, remove the four fuel injectors for test. It is found that there are bubbles coming out of the third cylinder fuel injector near the fuel injector and the copper gasket of the fuel injector. It proves that the internal seal of the fuel injector is not tight and there is oil leakage.

Step 8: replace the fuel injector, retest and solve the error.

Since the fuel injector belongs to the actuator on the engine, we can’t judge whether there is a error inside the actuator by reading the data flow and action test with the decoder. This fault belongs to the mechanical fault of the fuel injector and can’t be checked with the diagnostic equipment.
The reason why the water temperature is normal only when it reaches 70 ° C is that the needle valve and needle valve body of the injector are closed due to thermal expansion and the needle valve body is cracked, so the fault is eliminated after replacing the injector of the cylinder.
Summary: we must have our own ideas when troubleshooting. Like this error, we should first eliminate the faults of circuit sensors, and then solve other faults, and preliminarily judge whether there is a problem in the oil circuit. We don’t need to spend time and effort to check the low-voltage oil circuit, oil metering unit, etc.