How to diagnose engine performance by the color of the spark plugs?

Hello everyone)) in short, I had a distributor with a contact group, an old ignition coil and dead explosive wires

all this gave a Red spark ((((I’ll explain for those who don’t know - there are two types of spark: Blue and Red

So, a Blue spark means that the ignition system is working perfectly and the spark is strong and will ignite the mixture well, while the Red spark is weak. therefore it ignites the fuel mixture worse ((

There are many reasons why the spark can be red - in my case, the overall output of the units

due to the fact that I decided to exchange everything old for a new one, I bought a contactless ignition kit and new explosive wires

but then a problem appeared (((in the kit, the rod of the distributor (ignition distributor) turned out to be shorter than the original one - BUT I’m not going to give everything I bought to the store because of this))) we take two distributors, a screwdriver, pliers and swap the rods)))

everything is as it should be! put everything in its place and start! WOW, the spark is strong, BLUE, the engine starts with a kick and runs cleanly and without failures))

The quality of the spark on the spark plugs is checked in the same way as in its absence. However, it is advisable to change the gap with the high-voltage spark plug wire and ground. A spark is considered good if it penetrates a gap of at least 7 mm.

A weak spark on the spark plugs is a malfunction that occurs in the same way as when there is none at all, but it is much more difficult to detect the cause of its occurrence. An ammeter won't even be able to help in this case. The best way to determine a malfunction is to turn off a particular device or section of the circuit from the ignition system and try, if possible, to get a spark without them. The appearance of a good spark indicates a malfunction of the switched off device.

When, after checking, it turns out that the spark between the spark plug and the high-voltage wire is weak, turn off the distributor from the ignition circuit and check the quality of the spark between the ground and the high-voltage wire of the ignition coil. The presence of a strong spark indicates that the entire ignition system to the distributor is working, except for the distributor cap, rotor or high-voltage spark plug wires. If these parts are cracked or broken, they must be replaced.

If, when disconnecting the distributor, the spark remains weak, as before, you should carefully check all the clamps of the low voltage circuit, the cleanliness and reliability of the fastening. If, even after checking the terminals, the spark is weak, it is necessary to turn off the breaker from the low voltage circuit. Its action can be replaced with an additional wire, one end of which is connected to the point of connection of the capacitor wire with the low voltage wire coming from terminal P of the ignition coil, and the other is sharply struck to ground. In this case, the ignition coil wires and the capacitor must be disconnected from terminal K of the breaker.

Spark test

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It is recommended to test the spark in a dry room, such as a garage. There is no need to use any additional devices or complex equipment.

The ideal result is when the candle emits a bright blue color. In all other cases, when the color is white, red or another, there is something wrong with the system. The spark must be powerful, confident, appear constantly, and not periodically. The spark shouldn't be pink either.

If there is no spark at all, and the distributor is fully operational, it is recommended to check the spark plug itself directly. For example, you can install a known good one instead of the spark plug being tested.

On an injector, if the engine runs intermittently in idle mode or its power noticeably decreases, it is customary to talk about problems with the spark plugs. The Check Engin indicator can provide important information.

Types of soot

Diagnostic operations can be carried out independently, based on the instructions for replacing spark plugs. It is advisable to carry them out regularly to monitor the condition of the fuel system elements. Otherwise, the car will behave negatively while driving, for example, there will be vibrations in the engine compartment, intermittent power, etc.

It is important to know what color spark plugs should be in order to fully perform their functions, because unnecessary deposits that hide shiny metal contact surfaces prevent a spark from appearing regularly at the right moment. Before you find out what the color of spark plugs means, you need to understand what varieties there are.

The following colors are found in cars:

Before you find out what the color of spark plugs means, you need to understand what varieties there are. The following colors are found in cars:

The final color is determined by the chemical composition of the combustion mixture. An ideal working candle would be one that does not have a coating or contains small whitish salt deposits, resulting in the formation of a gray film. Also, in addition to shades, there should not be a high density of soot, which often appears in the following cases:

• low quality fuel;
• problems working with filters;
• defective equipment from unscrupulous manufacturers;
• discrepancy between the physical characteristics of spark plugs and internal combustion engines.

Once the causes are identified, it is worth getting rid of them as soon as possible.

Spark color

Thus, based on the color of the spark from the candles, the following conclusions can be drawn.

1. If the color is white with a blue tint, the spark is constant, then everything is fine.
2. If the spark is purple or transparent, colorless, you can draw conclusions about damage to the module, distributor or armored wires. Such a spark is knocked out at intervals or appears 1-2 times during testing.
3. A red or yellowish color indicates the presence of additives in the fuel.

Light electrodes

White or light gray spark plugs in all cylinders are a sign of a lean air-fuel mixture supplied by the injector or carburetor. Moreover, the skirt, area near the electrodes and the threaded part are absolutely dry, without traces of oil.

• lambda - the probe incorrectly informs the control unit about the amount of oxygen in the exhaust gases, the reason is sensor wear;
• faulty or clogged nozzles;
• incorrect carburetor settings or clogged fuel jets;
• insufficient pressure in the injector fuel rail;
• problems with the idle air control;
• air leakage under the manifold or in another place;
• unsuccessful chip tuning of the controller made by the owner of the car.

A lean mixture does not pose any particular danger to a running engine, but it does cause discomfort to the driver. The car accelerates slowly, pulls poorly and jerks - there is a lack of fuel. Oddly enough, the phenomenon causes increased gasoline consumption - a car enthusiast who wants to achieve better performance indicators presses the accelerator pedal harder and more often.

Candles

The appearance of the spark, its color, is also influenced by the candle itself and its condition.

Table: condition and appearance of candles

Common mistake

To obtain a reliable result, the inspection must be carried out after the engine has been running for a long time. Otherwise, the inspection result will allow you to draw erroneous conclusions. Quite often there is a situation when drivers start a cold engine in winter and, hearing the sound of its uneven operation, turn off the spark plugs and turn them out.

Seeing black carbon deposits, they draw premature conclusions about the malfunction of the power unit, forgetting that black carbon deposits can form due to the fact that at subzero temperatures the working mixture is forcibly enriched, and due to the fact that the engine is not warmed up to the optimal temperature, it does not have time to burn completely . Unstable operation may well be explained by a malfunction of high-voltage wires that need to be replaced long ago.

Red soot

Red carbon deposits are another common type of “spraying”. Usually, such a deposit does not mean that the engine is faulty, but is the effect of special additives. As you know, there are many different additive components in oil and fuel - they give the candle a reddish tone. Although when the ratio of additives is observed and the necessary standards are taken into account, deposits should not appear. The worse the quality of the oil (gasoline), the brighter the soot will be. It can even resemble rust. What kind of additives can create a similar redness effect? If we are talking about oil, then these are detergent additives. Although it is very difficult to make an accurate diagnosis here. When red carbon deposits appear, there is no need to do any diagnostic or repair work on the engine. All you need to do is change the oil, fuel and spark plugs (or just spark plugs).

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As you know, for an engine to operate, two conditions are necessary: ​​the presence of fuel and a spark to ignite it. In cases where the spark disappears, starting the power plant becomes impossible.

This applies to a situation where the spark disappears completely, but there may be no spark on individual cylinders, when the engine begins to trip, there is an unstable start, a decrease in dynamics and power against the background of increased fuel consumption.

The situations are different, as are the troubleshooting paths.

9 reasons why there is no spark at all:

Spark plug

The electrodes of the spark plug may become covered with an oil coating, carbon deposits may appear, sometimes completely closing the gap between the electrodes, an insulator breakdown may occur, the electrodes will burn out and the spark plug will fail.

Ignition coil

There may be an interturn short circuit in the ignition coil or a winding break.

Distributor distributor

The distributor may have faulty contacts, a Hall sensor, a broken slider, or a crack in the cover.

Egnition lock

The contact group in the ignition switch may be faulty (burning of contacts, melting of the plastic protrusion that controls the switching of contacts.

High voltage wires

The problem in the wires can be expressed in their cracking, burning of the internal core and breakdown of the external insulation.

Hall Sensor

In a contactless ignition system, the Hall sensor is responsible for interrupting the spark, failures of which are often caused by the loosening of its mounting bolts, or a breakdown of the sensor itself.

Crankshaft sensor

If the DCV fails or there is poor contact in the connection with the sensor, the engine will not start even if there is a spark in the ignition system. It is necessary to check the connection or replace the sensor.

ECU

If there is a failure in the electronic engine control unit, there may also be no spark and it is necessary to carry out computer diagnostics of the unit.

Engine weight

Ground wire – poor contact or broken connecting wire.

Procedure for checking the ignition system

In order to understand in what order it is necessary to start checking the system, let us briefly recall how it works.

Scheme of operation of the classic ignition system

When the key is turned to the “ignition” position, power is supplied through an additional lock relay to one of the terminals of the low-voltage primary winding of the ignition coil. The coil has two low-voltage terminals; from the second terminal, the coil is connected through a wire to the terminal of the distributor.

Then, when the engine starts, a high voltage is created in the secondary winding of the coil, which is supplied through its central high-voltage wire to the central terminal of the distributor cover.

Then the voltage is transmitted through the conductive part of the slider and the built-in resistance to the high-voltage wires to each cylinder, according to the operating diagram of the engine. The wires, in turn, transmit voltage through the tip of the spark plug to the spark plug itself, between the electrodes of which a spark ultimately jumps, igniting the air-fuel mixture.

To ensure that voltage from the coil is not constantly supplied, contacts are installed in the distributor that interrupt and connect the power circuit of the coil, depending on the position of the cams of the distributor shaft. If the contacts burn, the spark may also disappear.

Let's go back to checking the system

If the spark is lost, then you need to find exactly where the circuit broke, starting from the fuses (the circuit is not protected on all models), the ignition switch and then according to the described circuit, step by step checking the serviceability of all its elements.

So, if when you turn the key to the “ignition” position, the warning lights on the instrument panel light up, and there is voltage at the coil terminals, then the lock and the low-voltage circuit are working.

Next, you can check several elements at once. To do this, when cranking with the starter (an assistant is needed), the high-voltage wire is removed from one of the spark plugs, but not completely, but by holding the cap over the spark plug.

If the circuit is working properly, then clear clicks will be heard, otherwise the check must be started from the ignition coil.

Ignition coil

The armored wire from the ignition coil to the central socket of the distributor cover is removed from the cover and touches any metal part of the engine with a small gap. When turning the starter between the wire and the metal part, if the coil is working properly. there should be a spark.

If there is no spark and the high-voltage wire is in good condition, then the coil is faulty and needs to be replaced.

If the coil is working properly, you need to remove the distributor cover and first check the cover itself for cracks, and then the distributor slider.

Distributor slider

You can check the slider in two ways using the same high-voltage wire from the ignition coil or using a device, placing it on the “resistance”.

In the first case, with a contact ignition system, the crankshaft must be turned so that the contacts close, then, with the ignition on, bring the wire from the ignition coil over the slider with a small gap and use a screwdriver to open the contacts.

If the slider is “broken,” then a spark will jump between it and the wire; if not, then the slider is not piercing to ground. Then you need to use a tester to check the integrity of the noise suppression resistor installed in the spacer plate of the runner.

If the resistor “burns out,” then there will be no circuit and the slider will not be able to transmit voltage to the terminals of the high-voltage wires going to the engine cylinders. The slider needs to be replaced.

To get to the garage, you can remove the resistance from the slider and wrap it, for example, in cigarette foil and put it in place, this will be enough to get to the garage or auto shop. In general, it wouldn’t hurt if the driver had a spare slider in the glove compartment in case it breaks down.

Distributor contact group

If the slider is working properly, it is necessary to inspect the contacts for cleanliness and check whether they open when the distributor shaft is turned. If the contacts are working properly, then you need to check the power wire coming from the ignition coil at its entrance to the distributor.

Often the plastic insert cracks and the voltage goes to ground, thereby breaking the power circuit.

From practice.

There was such a case. The owner of the car, a person with driving experience, plus several neighbors in the garage, could not start the engine, although there was a spark when checking. With the ignition on, he brought the high-voltage wire from the coil to the engine ground and opened the contacts with a screwdriver - an excellent spark jumped out.

When cranking the starter, the engine did not start. Upon detailed inspection, I discovered that the plastic protrusion of the contacts, due to which they opened when they met the cams of the distributor shaft, broke off and the contacts simply did not open.

The contacts were replaced and the engine started with half a turn.

The second is a similar case, but with an ignition switch.

The six VAZs had already been towed for several hundred kilometers on trailers, getting to the house. We then worked outside the city. The next tug unfastened the rope and left, and the owner came to us with a request to sell the ignition coil, since, according to him, it was faulty and therefore there was no spark and the engine would not start.

Upon inspection, the following was found. The bolt on the coil where the low-voltage supply goes was literally torn out. We checked the coil and it is working, despite the loose bolt.

Next, we removed the contact group of the ignition switch, and it turned out to be a similar picture. The plastic protrusion that “commanded” the contacts melted. When the key was turned to the “ignition” position, the lights on the dashboard came on and the circuit was working properly; when the key was turned to the “start” position, the ignition circuit was opened and the starter spun in vain.

We removed the wires from the contact group, connected those responsible for the ignition, and “striking” the wires responsible for the starter, immediately started the engine. The owner was very upset that he paid so much for towing a working car.

The main reason for the raid

The first thing to consider is that the spark plug is necessary to ignite the mixture of fuel and air. The spark plug inside the cylinder operates under extreme loads in difficult conditions, where various chemical and biological effects are provided - this is the high temperature of the spark and processes during combustion of the mixture.

The main reason for the formation of soot is the chemical reaction resulting from the combustion of the fuel mixture. The reaction leads to consequences such as high temperatures and the formation of decomposition products. After each combustion of the next portion of the fuel mixture, a small amount of deposits settles on the electrodes of the spark plug and the cylinder walls.

Normal gap, what you need to focus on

We have very specific limits. Bottom from 0.4 mm (and everything below), top from 1.3 mm (and everything above). So what is considered the normal size for your car?

You know, there are differences here too, they are connected primarily with the car’s ignition system, which can be roughly divided into three types:

1) For carburetor type, with distributor - normal clearance is from 0.5 to 0.6 mm

2) For carburetor type, with electronic ignition – 0.7 – 0.8 mm

3) Injector – 1 – 1.3 mm

Why such difference? - you ask. The answer is simple - it's a matter of the ignition system and electrical circuit. The carburetor has the lowest voltage, so the spark will be weaker, and therefore the gap should be smaller. But the injector has the strongest energy system, so here the gap is increased, normal is considered to be 1 mm, and on many foreign cars it is 1.1 mm.