The decrease in the number of engine revolutions significantly affects its power and traction. If suddenly your car has lost its former playfulness, it is worth thinking about its diagnosis, because such symptoms do not bode well.
In this article we will talk about why the engine does not develop revolutions and with what it may be connected. We will also consider the probable causes of power loss by the power unit and methods for their elimination.
Symptoms
It is not difficult to determine that the engine does not develop the speed that it should develop, especially if you have driven a car before and know its native characteristics. Those drivers who have encountered a similar problem in their practice know that power reduction is characterized by slow acceleration, loss of dynamics, traction, as well as overheating of the engine and increased fuel consumption. Sometimes these processes are accompanied by gray or even black exhausts.
Do you press the accelerator pedal and the engine does not develop well? Pay attention to the tachometer. A serviceable engine should immediately respond to an increase in the amount of fuel supplied to the combustion chamber by increasing the number of crankshaft rotations. And if this does not happen, you need to urgently look for a malfunction.
Main reasons
There can be a lot of reasons why the engine does not develop revolutions. Here is a list of the most common ones:
- the power unit is not warmed up to operating temperature;
- low or, conversely, excessive fuel level in the float chamber;
- accelerator pump is faulty;
- clogging of nozzles, carburetor channels;
- air intake in the intake manifold;
- incorrect ignition timing;
- gas distribution phases are violated;
- gaps of spark plugs are broken;
- clogged air or fuel filter;
- malfunction of mass air flow sensors, crankshaft position, throttle position, detonation;
- insufficient compression in the cylinders, etc.
As you can see, the list is quite lengthy, although it cannot be called complete. Consider the more detailed listed faults.
Cold engine
It will be wrong to demand full power from the power unit until its temperature reaches the operating indicator (90 0 C), especially when it comes to a carburetor engine. A cold engine does not reach full speed even when the choke is completely closed. The fuel mixture must be warmed up before it enters the combustion chambers. Otherwise, the car will “twitch”, and the motor will stall and detonate. So, if your car is equipped with a carburetor engine, do not rush to leave until it warms up.
Fuel level in the float chamber
The fuel level in the float chamber is also able to affect the operation of the power unit. If it is below the prescribed, the concentration of gasoline in the combustible mixture is reduced. Because of this, the engine does not develop power. At an overestimated level, the mixture, on the contrary, is too enriched, but it enters the combustion chamber more than the norm. Before entering the cylinders, it does not have time to warm up in the intake manifold, which leads to the occurrence of detonation and loss of speed.
The fuel level is regulated by bending (bending) the fasteners of the floats.
Accelerator pump, carburetor channels and jets
Continuing the theme of the loss of power of the carburetor engine, one can not help but mention the accelerator pump. It is from its operability that the response of the power unit to pressing the accelerator pedal depends. Most often, the problem is the fuel supply, and the “nozzles” of the atomizer, through which gas is supplied by a thin stream, are to blame. To check the performance of the carburetor accelerator pump, you will need to remove the air filter so that you can see the first chamber. Next, you need to open the throttle and hold it for a few seconds. At the same time, a thin (about 1 mm) trickle of fuel must be pulled out of the “nose” of the accelerator, directed exactly into the second chamber. If the jet is low-power or the curve is a sign of clogging of the atomizer, nozzles, valves of the accelerator pump. This problem is solved by cleaning them.
Intake manifold air leaks
Another reason why the engine does not develop revolutions may be a banal suction of air in the intake manifold of the power unit. Symptoms of such a malfunction are the difficulty of starting the engine, its “triple”, problems with idling, increased fuel consumption and, naturally, loss of speed. This is all due to the sharp depletion of the mixture due to unaccounted air entering the combustion chamber.
Most often, depressurization of the system occurs due to wear on the intake manifold gasket. It is rather difficult to determine that the injection engine does not develop revolutions precisely because of air leaks, as it is not easy to find the place of depressurization itself. It is better to entrust it to specialists. But you can try to do something yourself. You can, for example, take a syringe with a needle, fill it with gasoline (or diesel fuel for diesel units) and treat the junction of the collector with the engine along the perimeter with fuel. If the gasket between them is unusable, then gas will be sucked into the combustion chambers along with air. If, starting the engine, you notice positive changes in its operation, you can be sure that the reason lies precisely in the leak.
Incorrect ignition timing
It often happens that unlucky car owners, wondering why the engine does not develop revolutions, forget about the ignition moment, although it is he who plays a crucial role in the operation of the power unit. The timely ignition of the fuel mixture in the combustion chambers depends on it. If the ignition timing is set incorrectly, you will never achieve the coordinated operation of all engine systems and mechanisms by any means and methods.
In injection power units, the corresponding sensors are responsible for the right moment. Their job is to collect information and transfer it to the electronic control unit, which in turn adjusts the angle. There are no such sensors in carburetor engines, so the ignition is set manually by scrolling the top of the ignition distributor.
Setting the right angle yourself and without special equipment is not easy, although it is possible. At service stations, a special strobe is used for this, with which a specialist determines the position of the mark on the crankshaft at a certain position of the distributor.
Disruption of the valve timing
Disruption of the valve timing usually occurs when the timing belt breaks or when it is replaced. Having made a mistake in the form of a shift of at least one “tooth” between the gears of the crankshaft and the gas distribution mechanism, you will get a real problem in the form of unstable engine operation, increased fuel consumption, color exhaust and other troubles.
In order not to fall into a similar situation, work on replacing the timing belt and repairing all the elements associated with it should be carried out at service stations. Well, if this is not possible, then it is necessary to carefully check and double-check the correspondence of the marks on the timing gears, crankshaft and flywheel.
Electrode Gaps
The next reason why the engine slowly develops revolutions or does not develop them at all may be the wrong gap between the electrodes of the spark plugs. There was a normal car with a normally working engine, but you didn’t like something, and you decided to change the candles, but did not read the recommendations of the manufacturer. An error in the gap of one tenth or one hundredth of a millimeter will certainly make negative adjustments to the engine. Depending on its increase or decrease, this can be a difficult start, loss of traction, reduced power, excessive fuel consumption, etc.
If we are talking about the gaps, we can not mention the two-stroke engines. For them, candles are one of the most important elements that ensure the stable operation of the motor. So, if the two-stroke engine does not develop revolutions, the first thing to do is to check the condition of the electrodes and the gap to the recommended values.
Clogged air and fuel filters
Is it worth it to say once again that the filters need to be changed every 7-10 thousand kilometers, and in special operating conditions twice as often. Contamination of these elements causes difficulties with the supply of fuel or air to the manifold and leads to disruption of normal engine operation. The lack of normal fuel pressure in the fuel line causes the fuel mixture to become leaner, and if problems arise with the air supply, it is re-enriched. In both the first and second cases, the engine "suffocates", overheats, loses power, speed, consumes more fuel.
This malfunction is eliminated by replacing the filter elements.
Sensor malfunction
Compared to the carburetor, the injection engine wins due to the fact that its operation is electronically controlled, and if any problems arise, the driver will know about them by the error signal on the control panel. He will only have to connect the tester and read the code to determine which of the nodes is out of order. This is due to electronic sensors that monitor the operation of the main systems and mechanisms. But they are not eternal.
If any of them refuses to work, the engine goes into emergency mode. Due to the fact that the electronic unit ceases to receive the necessary information, the operation of the power unit becomes unstable.
Insufficient compression
And finally, the most unpleasant malfunction, which leads to a decrease in speed and loss of engine power - insufficient compression. It is the result of wear of the piston group parts or occurrence (coking) of the piston rings. As a result of this, the pressure in the combustion chambers decreases, and part of the energy from the combustion of the combustible mixture is simply lost.
Compression is measured using a compressor. Its normal performance, depending on the type of engine, can vary from 10 to 14 kg / cm 2 . Having found a similar problem, you should think about the overhaul of the engine.