Diagnosis and troubleshooting of common faults in conventional ignition systems

Common faults of ignition system

A defective ignition system is also the cause of unstable idling, unpleasant refueling and other malfunctions, and the culprits are mainly damaged spark plugs as well as high-voltage wires. Ordinary spark plugs need to be replaced every 40,000km, and expensive platinum spark plugs every 100,000km. When the expiration date is reached, they must be replaced without mercy.

With the prolongation of the use of time, the high temperature and high heat of the engine work and the usual maintenance in the irregular folding, pulling, bending and other rough dismantling methods, which may lead to the spark plug internal core wire is broken, the resistance of itself greatly increased, so that the high-voltage electricity can not be completely enough to deliver to the spark plug and make the spark plug "cut off the fire" or "jump-start energy". The spark plug will not be able to deliver enough high voltage power to the spark plug to make the spark plug "cut off" or "jump-start energy" is not enough to ignite the combustible mixture, and the corresponding cylinder will not be able to do the work or work abnormally, which will seriously affect the output of the engine power.

Gasoline engine ignition system common troubleshooting methods - weak spark

①Phenomenon

will be the high-voltage wire from the body of 5-7mm test, the spark is very weak and red, resulting in the machine is not easy to start, the work of the operation of the unstable.

② Causes

The battery voltage is too low or poor wire contact (refers to the battery ignition system).

Low-voltage circuit contact is poor.

Platinum contacts too dirty, burned, uneven or improperly gapped.

Improper capacitor capacity or leakage.

Ignition coil is locally shorted, damp or overheated.

Improper bit angle adjustment.

Leakage or breakage of high voltage wire.

Demagnetization of the magnet or excessive magnetic resistance.

Improper spark plug gap, excessive carbon, leakage.

③Analysis and troubleshooting

The method of compression failure is basically the same as when there is no spark. First, use the high-voltage wire to test the spark, to determine whether the fault is in the spark plug or magneto (or distributor), high-voltage wire. If the fault is in the magneto, you can check the platinum contact, then adjust the bit angle, and then check the capacitor, ignition coil, magneto and magnetic circuit. Judging the quality of the capacitor, ignition coil and magneto can be used to replace the comparison method, which is both simple and accurate.

1 on the gasoline engine ignition system common failure analysis

Abstract most of the vehicles used by my company are gasoline vehicles, gasoline engines have many common failures, the most common failure is the failure of the ignition system. Then this I will find the causes and judgment of some of the methods slightly summarized, with comrades to discuss.

Topic word gasoline engine ignition system failure

China Road and Bridge Group Highway Bureau is a larger highway construction enterprises, in the current road construction, most of the machinery used is a diesel engine, gasoline engines are mostly used for transportation and logistics. The gasoline trucks are said to have little impact on the construction of the project, but the logistics work, if not kept up in time, will be a great constraint on the front line of the construction.

I have been working in the machinery department since 1996, and I know the importance of logistic support. Like my Bureau of the supply of accessories for various projects are mostly their own procurement, most of the vehicles used are gasoline vehicles, once the breakdown, will affect the timely supply of accessories, further affecting the recovery of the front-line construction machinery, affecting the progress of construction.

There are many common failures of gasoline engines, and the most common failure is the failure of the ignition system. Here again I will find the causes and judgment of some of the methods slightly summarized, with comrades to discuss.

The cause of the ignition system, in general, there are three reasons:

1, the primary circuit power loss.

2, secondary circuit power loss.

3, ignition time is not right.

Causes of primary circuit power loss:

1) too much resistance. Broken wires, wiring is not secure, breakers contact erosion, ignition coil primary winding broken wire, ignition switch contact is not good and so on.

2) Oil on the surface of the disconnector, insufficient spring force of the disconnector arm.

3) Loss of battery charge, poor or faulty generator performance, regulator out of adjustment.

4) Short circuit. Ignition coil, distributor, and sections of wire in the primary circuit have lap faults.

Causes of loss of electrical energy in the secondary circuit:

1) Leakage in the high-voltage ignition wire.

2) The ignition coil end cap, distributor cap and distributor head have cracks and leakage occurs.

3) Spark plug ceramic core broken, electrode ablation or deformation, spark plug gap is too large or too small.

4) The high-voltage ignition wire is not connected securely.

Causes of misalignment of ignition timing:

1) Ignition advance angle adjustment error.

2) Bent distributor shaft and worn bearings.

3) Vacuum regulator leakage.

4) Centrifugal regulator hairpin.

5) Incorrect spark plug selection, center pole overheating.

The cause of engine ignition failure is mainly due to the above reasons, for the above aspects of the cause, careful search, it should be easy to find the cause.

The following for the fault to find explained.

With the help of instruments can certainly quickly and accurately determine the part of the fault occurred. However, maintenance personnel and drivers should master the fault phenomenon step by step to find, determine the fault part of the skills, in order to work in a timely manner in the daily work of some of the minor problems that occur, the smooth completion of the work. Listed below are several common faults of the query steps.

1, engine start without fire

If the engine carburetor oil level is normal, acceleration nozzle spray normal, should check the ignition system failure.

If the starter is working vigorously, should check the spark plug jumping fire. From the spark plug to unplug the cylinder high-pressure wire, its end close to the surface of the cylinder head, 3 to 5 millimeters apart. Start the starter and observe the tripping condition of this high-pressure wire. If the cylinder high-pressure wire can jump out of the pop, pop white spark, the fault occurs in the spark plug. Check each cylinder spark plug dirt, oil, if necessary, replace the spark plug. If the high-voltage wire end of the jumping fire is not good, should be started at the same time, check the car ammeter needle and against the following points to judge:

1) If the ammeter needle with the rotation of the starter motor and swing, can be initially identified as a fault in the secondary circuit. Should check the sub-cylinder high-voltage line, distributor, distributor head center high-voltage line and ignition coil failure. For example, the cylinder high-pressure line does not jump fire and the center of the high-pressure line jump fire normal, you can check the center of the distributor cover charcoal fine contacts are missing, whether the distributor head is missing the distributor cover is cracked leakage and so on.

If the ammeter pointer does not swing with the rotation of the starter, and the index is greater than 4A, it can be assumed that the fault exists with the primary circuit, should be checked in turn whether the contact gap of the breaker is too small, the capacitor whether it is punctured or has been leaking, each part of the connecting wires whether the existence of the hitch fault.

2) If the ammeter pointer indicates zero, it can be recognized that there is a broken circuit fault in the primary circuit. Should check the ignition switch, starter switch auxiliary contacts, additional resistance and ignition coil low-voltage terminals are all voltage (with a screwdriver will be the points in turn iron, can see a weak spark or ammeter swing). Disconnector contact gap is too large. Can also use a multimeter instead of a screwdriver to check, that is, with a DC 25V gear. A meter pen connected to the engine body, another meter pen in turn contact with the above points, the break point is bound to be in the multimeter with and without the number of points between the two measurements.

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2 about the gasoline engine ignition system common failure analysis

2 , engine Work is unstable, the sound is not continuous.

Engine irregularly shaking, sound high and low or discontinuous phenomenon, this is the ignition system lack of fire (or cylinder) to. You can use a screwdriver to short the spark plugs in turn, while listening to the sound of the engine (or observe the fan blade rotation). Normal spark plug is shorted, the engine speed will be significantly reduced, the sound becomes muffled (or fan blade becomes clear). If this phenomenon is not present when a spark plug is shorted, it means that the spark plug in this cylinder is not working well. The smaller the change in speed and sound, the more serious the lack of cylinder. Can be unplugged from the spark plug on the high-pressure wire test fire. If the spark is strong, then the spark plug should be disassembled and checked; if the spark is weak, you can check the high pressure line and the distributor cap of the leakage faults of this cylinder. Of course, the valve stuck and cylinder gasket burned through a similar phenomenon, but the phenomenon is more regular, randomness is very small. If you check according to the above method, the response of each cylinder is similar, indicating that the lack of cylinder phenomenon is random for each cylinder, the fault exists with the previous part of the distributor. Disconnector contacts should be checked for corrosion, staining, gap misalignment, and fixed disk loosening and other faults. Sometimes the distributor bushing wear, the high-voltage wire plugging is not secure, the spark plugs generally carbon or engine piston ring scuttling on the oil will also cause similar phenomena.

3, engine powerlessness, backfire and discharge

In most cases, the exhaust discharge and carburetor backfire is caused by improper carburetor dosing. However, in the distributor adjustment error, ignition advance angle deviates too much from the correct position also cause backfire and discharge. In case of backfire, you can try to move the distributor along the direction of rotation of the distributor head (both delayed ignition angle); in case of exhaust discharge, you can try to move the distributor against the direction of rotation of the distributor head (both increase the advance angle), or readjust the distributor's mounting position according to the manual. For the general engine, the distributor can be adjusted at idle in its installation position; both slightly above the idle speed of the throttle opening, choose to make the highest engine speed, the sound of the loudest position to fix the distributor.

If there is both backfire and discharge and the sound is very serious, mostly due to the high-pressure line of the cylinder has the wrong phenomenon. If the phenomenon is not serious, but intermittent, seemingly regular, most likely the distributor cover has a line, so that the inter-cylinder fire caused.

4, engine shock or overheating

Engine in a large load (such as heavy load uphill) is most likely to occur when the medium speed shock. If the empty car on a flat road to test the presence of vibration chamber, you can first use the direct gear at medium speed, and then step on the gas pedal to listen to the engine with or without the crisp sound of da-da-da.

In the case of using the correct fuel grade, most of the vibration phenomenon is caused by the ignition advance angle is too large, should be pushed back the distributor device angle.

The ability of various models to withstand detonation is different. Generally speaking, the high compression ratio, heavy workload of the car's ability to withstand vibration is relatively weak. For example, Jiefang brand CA10C, CA15 will not have an accident if they work under a slight burst of vibration, however, for the new CA141, you should try to avoid working under a burst of vibration.

Working in the burst, the engine will heat up quickly, the cooling water temperature will rise a lot, or even "boil". On the other hand, the ignition advance angle is too backward, the engine temperature will also rise. This is because the ignition is too late fuel combustion rate is too slow to catch up with the expansion of the requirements of the work, the remaining large amount of energy, had to be in the form of heat to the cylinder dispersal or taken away by the exhaust. Therefore, in the case of the car does not appear to burst, high water temperature is not caused by the ignition system. However, if accompanied by engine weakness, acceleration is not sensitive (commonly known as "not revealed"), should check whether the ignition advance angle is too small, should be adjusted to increase the ignition advance angle.

A step-by-step search for faults is a better way to diagnose the four common faults listed above is one of the examples. Of course, in practice, but also pay attention to the flexible use. For example, we once encountered engine instability, the sound is not continuous, after the investigation of a spark plug cylinder high pressure wire does not jump fire. According to the general logic, we believe that the problem lies between the distributor and the high voltage line of the cylinder. However, after checking, there was no fault in this section, and after further inspection, we found that the problem was in the distributor camshaft. Both 492 engine distributor cam, exactly one cam can not top open contacts. Caused by the lack of cylinders and, for example, once our double row of cars after starting the idle speed is normal, but a gasoline on the fire. According to logical analysis should be a carburetor failure. But the actual repair results of the break arm low-voltage lead broken, in the large load work, vacuum advance angle back to zero when the broken skin at the hitch, which is also one of the causes of engine starting difficulties.

There is also the engine motor when the engine has been on fire work, just relax the starter, the engine is followed by a flameout. According to the routine can be suspected of carburetor idle speed is adjusted too low, the actual test is found to be the additional resistance of the ignition coil broken wire.

In short, in the repair work, both to keep the program organized work, but also with the actual consideration of the problem, but also a combination of knowledge to be integrated into a comprehensive consideration, in order to solve the problem quickly and accurately.