Fault diagnosis and troubleshooting of engine start failure

Category:Automobile engine repair - Date:2016-02-22

1. sub cylinder fire test:

Pulling down the high pressure line of the arbitrary cylinder spark plug, starting the engine to carry on the fire test (according to the prescribed fire), if the fire or spark is weak, the ignition system can be preliminarily diagnosed as the ignition fault. If the spark is normal, the next step is carried out.

2. inspection of oil road:

fuel pressure, injector and so on. If the fuel pressure is normal and the fuel injection is normal, the next step is to check.

3. dismantling the spark plug: remove the spark plug and check whether there is water on the spark plug and whether there is oil. And check the gap of spark plug electrode, the quality of electrode, and do jump fire test. If the spark plug is normal, the next step is carried out.

4. check ignition timing:

(1) a cylinder piston to the TDC, check whether the distributor rotor to a cylinder cylinder head on. If not, the adjustment is made. (2) jump fire: check whether distributor is in the position of exactly high pressure jump, otherwise it should turn the distributor shell adjustment. (3) check the cylinder line sequence: Santana four cylinder engine firing sequence is 1-3-4-2 (clockwise).

5. check cylinder pressure:

use cylinder pressure gauge to measure cylinder by cylinder, and measure three times per cylinder. The maximum value should be up to the technical standard.

6. inspection of the interior of engine machinery:

When the cylinder pressure is used to test the cylinder pressure, the cylinder pressure meter pointer rises very little at the moment when the starter is just rotating, and then it rises gradually from the low, but still can not reach the standard pressure, then it may be the air leakage of the cylinder, piston and piston ring. If the cylinder pressure gauge pointer rises very little when the starter is just turning, then the cylinder pressure reading is still very low. Generally, the valve leaks. The pressure of the adjacent two cylinder manifolds decreased and the intake pipe was tempered when the engine was running. It was determined that the cylinder pad was washed out, and the cylinder body and cylinder head were unevenly combined to lead to gas leakage. It can also detect cylinder pressure, check crankcase volume, air leakage rate and inlet vacuum degree to determine internal fault by adding oil.

Note:

when.1. starts the engine, it can't start for more than 5 seconds, and the time interval between two start engines is no less than 30 seconds.

2. should operate according to cylinder pressure gauge when using cylinder pressure gauge.

3. should be far away from the open fire when the fuel injection is checked.

Technical standards and requirements:

1. gasoline engine can start smoothly, idle speed, medium speed and acceleration are good.
the voltage of.2. battery is up to the standard, and the gap of spark plug is generally 0.7 to 0.8mm.
3.. The cylinder pressure of the general car is 1 ~ 1.3MPa, the cylinder pressure of each cylinder is not less than 15% of the standard value, and the cylinder pressure difference is no more than 3%.
4., the crankshaft volume is 2 ~ 4L/min, and the air leakage rate of the cylinder is 30% ~ 40%. When idle speed is running, the intake pipe vacuum is 57 ~ 72kPa.

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