There are three common cold faults in the winter: the cold car is not easy to start, cold crank starter jitter and poor cold car speed, many maintenance personnel do not know how to encounter these failures start, car experts on these three kinds of "cold "Failure to analyze and resolve.

Symptom:

(1) cold car is not easy to start

In the automotive repair standards: -5 ℃ above the ambient temperature, each time the use of starter 5s, up to 3 times the engine should be started. With today's automotive technology content, many users of this standard has long been disapproved, they want to use the starter in 5s should start successfully, and modern electronic control engine generally can do. If the engine is difficult to start the fault, the fault usually include: ① start the system failure, such as battery power shortage, starter damage or starter circuit failure. ② engine mechanical failure, such as the intake air pipe leak, piston and cylinder closed between the poor, and the valve closed lax cylinder pressure is low. ③ intake valve back into the trachea and the accumulation of carbon too much, resulting in the injection of gasoline by carbon adsorption can not enter the combustion chamber. ④ engine management system failure, such as the speed sensor signal is weak, the water temperature signal is not correct, and poor line contact. ⑤ ignition system failure, such as excessive spark plug or gap is not correct, high-voltage leakage, and the ignition coil damage. ⑥ oil supply system failure, such as fuel system to maintain the pressure is insufficient, injector leakage or blockage.

 (2) cold engine idling jitter

Engine cold start, if there is no cold engine idle speed or unstable speed instability, the failure of the reasons in general include: ① engine mechanical failure, such as the cylinder pressure is low. ② intake system failure, such as the intake pipe leakage. ③ intake valve back into the trachea and excessive carbon deposition. ④ engine management system failure, such as water temperature, intake air temperature signal is not correct, there is fault line. ⑤ ignition system failure, such as excessive spark plugs or gap is not correct, high voltage lines, electrical leakage cover, and the ignition coil damage. ⑥ fuel supply system failure, such as fuel injector internal glial too much coke caused by improperly closed or injector blockage.

(3) cold car to accelerate Chuang car

Although many automobile manufacturers use instructions on the cold start can not start without preheating, but I think that if the engine after starting a little warm-up 3 ~ 5min, the engine will be of great benefit. Because it can reduce the mechanical wear of the engine, the small displacement engine can make start power sufficient. If the cold start after the car will appear to accelerate a slight car Chuang phenomenon, if Chuang car phenomenon is serious, the fault is generally due to: ① engine mechanical failure, such as low cylinder pressure led to engine power decline in the cold state is more prominent. ② intake valve back into the trachea and the accumulation of carbon too much, resulting in the injection of gasoline by the carbon adsorption can not enter the combustion chamber. ③ engine management system failure, such as water temperature, intake air temperature signal is not correct, line failure. ④ ignition system failure, such as excessive spark plug or gap is not correct, high-voltage lines, distributor cover leakage, ignition coil damage. ⑤ fuel supply system failure, such as fuel injector internal glial too much coke caused by improperly closed or injector blockage.

Fault countermeasures

The diagnosis of the above three faults should be followed after the first power machine, the principle of simple and then the first fan, if the engine at the same time there is not easy to start a hot car, hot car idling jitters and hot car bad acceleration of the "three thermal failure" . Diagnosis steps are as follows: ① check the appearance of the engine, check the vacuum tube, wiring harness plug with or without shedding, whether there is leakage, leakage, oil spills and water leakage. ② Use the fault diagnostic device to query the fault code and data flow. ③ with a multimeter, oscilloscope and other equipment for measurement. ④ According to the above check to determine the cause of the malfunction and parts, repair or replacement parts. ⑤ After troubleshooting with the above equipment for testing.