Cold car difficult start failure analysis

Many car owners have encountered various problems of cars. Cold car start-up is a big problem that has plagued car owners for a long time. Many car owners can't start cars in the case of car cold cars, which is not good for car maintenance. It is also because many riders do not understand the working principle of some components of the car. When the riders understand these related knowledge, they can solve various car problems in time. The following are some of the small series for the riders. Some related questions about the difficulty of starting air-conditioning in automobiles.

1 engine mechanical system failure, such as air intake pipe leakage, the piston and cylinder are not tightly closed, the valve is not tightly closed, the intake valve and the intake pipe are too rich in carbon, causing the injected gasoline to be adsorbed by the carbon and cannot enter the combustion. room;
2 engine management system failure, such as weak speed sensor signal, incorrect water temperature signal, poor line contact, etc.;
3 There is a fault in the ignition system, such as excessive accumulation of carbon in the spark plug or incorrect gap, leakage of the high voltage line, damage to the ignition coil, etc.;
4 The oil supply system is faulty, such as keeping the pressure insufficient, the injector leaking or clogging.
Cold car idling
If the cold car idle speed jitter and the hot car idle speed jitter exist at the same time, the hot car idle speed jitter fault is first eliminated.
Defining whether it is a jitter should observe whether the engine tachometer pointer swings, or read the engine speed in the data block, because the engine foot pad damage can also cause engine idle speed jitter, especially after the automatic transmission is engaged in the forward gear.
The reasons for the idling of the cold car are:
1 engine mechanical failure, such as uneven pressure of each cylinder;
2 Intake system failure, such as air intake pipe leakage; excessive intake of intake valve and intake pipe, excessive dirt on the inner wall of the throttle and intake pipe;
3 engine management system failure, such as water temperature, intake air temperature signal is incorrect, line fault, etc.;
4 There is a fault in the ignition system, such as too much carbon deposit in the spark plug or incorrect gap, high voltage line, leakage of the distributor cover, damage to the ignition coil, etc.;
5 The oil supply system is faulty. For example, the fuel injection is not tight or blocked due to excessive carbon deposit inside the nozzle.


Cold car acceleration
Although many auto manufacturers' user manuals indicate that there is no need to warm up after the cold start, they can start, but I think it is beneficial to warm up slightly for 3~5 minutes after starting the engine, because it can reduce the mechanical wear of the engine and reduce the small displacement. The car can make the engine powerful at the start.
The start of the cold car big throttle is the wrong driving method. At this time, the acceleration seat car can be avoided. If the cold car slowly refuels, the car will be faulty.
The reasons for the poor acceleration of the cold car are:
1 engine mechanical system failure, such as low cylinder pressure, resulting in reduced engine power, more prominent in the cold state, too much carbon deposits in the intake and intake pipes;
2 The intake valve and the intake pipe are too rich in carbon, which causes the injected gasoline to be adsorbed by the carbon deposit and cannot enter the combustion chamber;
3 engine management system failure, such as water temperature, intake air temperature signal is incorrect, line fault, etc.;
4 There is a fault in the ignition system, such as too much carbon deposit in the spark plug or incorrect gap, high voltage line, leakage of the distributor cover, damage to the ignition coil, etc.;
5 The oil supply system is faulty. For example, the fuel injection is not tight or blocked due to excessive carbon deposit inside the nozzle.
For the above faults, follow the principle of first electric power, first simple and then complicated.
If the engine has a hot car failure at the same time, the hot car failure should also be eliminated.
The diagnostic steps are:
1 Check the appearance of the engine, such as vacuum tube, harness connector plug-off, whether there is air leakage, leakage, oil leakage, water leakage;
2 use the computer diagnostic instrument to query the fault code and read the data block;
3 Use a multimeter, oscilloscope and other instrumentation to measure;
4 According to the above inspection to determine the cause and component of the fault, repair or replace the accessories; 5 after the fault is removed, use the above instrument to test again;
6 Reproduce the fault occurrence conditions for testing or road test.