The most unpleasant kind of problem is when something in the car is half broken. In such cases, troubleshooting becomes a complex task, reminiscent of catching fleas. A common example: the engine does not rev up after pressing the accelerator pedal. The car is driving, but it is not capable of accelerating to normal speed - the motor “sneezes” and stalls. If you decide to find the problem yourself, check out complete list reasons causing inappropriate behavior of the power unit.
Fuel system problems
If you encounter a problem with a drop in engine power, start looking for a problem with the fuel supply system. After all, if the engine does not respond to opening throttle or it starts to stall, it is logical to assume that it simply lacks fuel. Your actions:
- Remember when the fine filter was changed and check its condition. The clogged filter element does not allow enough gasoline to pass through, which is only enough for work on Idling without load.
- A common reason is a fuel pump mesh clogged with dirt, located in the tank. Often, motorists ignore its replacement, installing only new filter... To check the coarse mesh, you will have to disassemble the gas tank and pull out the pump.
- The pressure relief valve has failed, dumping excess fuel back into the tank. It is checked by measuring the pressure in the fuel rail through a special fitting.
- If you smell gasoline in the closed garage where the car is stored, walk along the entire fuel line while inspecting for leaks.
Note. A clogged filter is indicated by the prolonged noise of the fuel pump, audible after the ignition is turned on. The unit cannot raise the pressure in the line to normal and does not turn off for a long time.
More serious problems are more difficult to detect. Both gasoline and diesel engines can suffer from malfunctioning or failure of injectors. Their performance is checked by removing and connecting to a power source. The sprayer must create an even, beautiful "torch", otherwise it must be replaced.
The reason for the lack of fuel in diesel engine often becomes a fuel pump, which creates high pressure in the system. When the parts of the unit are worn out, the pressure in the line drops below normal, and little diesel fuel is injected into the cylinders.
Together with the fuel filters, it will not hurt to check the air filter. Blow out the contaminated element if you cannot immediately change it.
Ignition faults
In cases when, when pressing the gas pedal, a lumbago is heard in exhaust pipe or the engine starts to "triple" on idle, try to troubleshoot the ignition system. Weak sparking at the spark plug electrodes leads to incomplete combustion of the air-fuel mixture and a loss of power in the power unit. The reasons for the malfunctioning of the system look like this:
- Problems with one or more high voltage coils.
- The insulation of the high voltage wires leading from the coils to the candles has leaked.
- Due to the long service life, the candles themselves have worn out.
The trick of worn-out candles is that they give a normal spark during testing.... But there is high pressure in the cylinders of the engine, at which the old candles are extinguished. That is why the engine does not develop revs, and a sharp depression of the accelerator pedal causes a "failure". It is necessary to check the candles on a special stand that creates a pressure of at least 20 bar.
Diagnose breakdown high voltage wire or candle insulation can be in a dark garage. Open the hood, start the engine and watch it work. If you notice flashes of sparks on the "cradles", put new parts.
A failure of the coil or a break in the high voltage wire is evidenced by the complete failure of one of the cylinders. Testing the wire is easy: swap it with the adjacent one and make sure the other cylinder stops working. This technique will not work with coils; special equipment is needed for diagnostics.
Motor problems
Critical wear of the cylinder-piston group of the power unit also leads to a decrease in power. There are other reasons why the engine revs poorly:
- burnout of a valve in one or more cylinders;
- lack of compression or its fall below the permissible level;
- incorrect adjustment of thermal clearances between valve stems and rocker arms;
- malfunctions of the timing belt or chain drive.
Most of these malfunctions are detected by measuring the compression. A burnt-out valve does not completely fit into the seat, which is why the pressure in this cylinder drops to 2-3 bar, and sometimes to zero. The general decrease in compression in all cylinders to the level of 9 bar and less indicates a "playful" piston rings.
Advice. Before announcing the verdict to the cylinder-piston group, it is worth checking thermal clearances probe. If recently some "specialist" made an incorrect adjustment and clamped the valve, then the compression will also decrease.
Similar errors occur when replacing the timing chain or belt, when the marks are shifted by 1 tooth. The consequences are a violation of the valve timing and loss of power, plus unstable engine operation. A similar effect is encountered by careless drivers who do not follow their own car: from wear, the chain (belt) stretches strongly and jumps on the gear camshaft 1 prong.
Too much high consumption oil entering the combustion chambers through the valve seals also worsens the operating conditions of the power unit. From the inside, the walls of the chamber and the electrodes of the candles are covered with carbon deposits, and the piston rings coke and lie. A sure sign of a malfunction is a cloud of gray smoke from the exhaust pipe.
Other problems
A modern car is equipped with electronic system control of the power unit and neutralization of flue gases. Since the technical condition of these systems directly affects the operation of the engine, power loss can occur for the following reasons:
- destruction and complete obstruction of the catalytic converter installed in the exhaust tract of a gasoline engine;
- a clogged diesel particulate filter has the same consequences - the exhaust gases have nowhere to go and power unit"Suffocates";
- failure of one or more sensors associated with the electronic control unit.
Checking the patency of the catalytic converter and particulate filter is simple: unscrew the front flange of the device, opening the way for the exhaust gases, and start the engine. If its performance improves significantly, replace the catalyst with a new one either.
When the lambda probe fails, the engine does not pick up speed at the command of the controller. Without "seeing" the amount of oxygen at the outlet, the electronic unit cannot properly prepare the air-fuel mixture, therefore it goes into emergency mode... The mixing of fuel with air occurs according to the established indicators, which reduces the engine power.
The transition to the emergency operation mode is accompanied by the inclusion of the display Check Engine on dashboard... A malfunction occurs whenever one of the main sensors fails - the mass air flow sensor (in new cars - MAP), the lambda probe or the throttle position sensor. To check the performance of these devices, it is better to contact a competent auto electrician or a service station.
Many have at least once had to deal with a situation when a motor that worked perfectly before is "blown away", the machine seems to grow an anchor from behind. The reasons why the engine does not pull and does not pick up speed are different, but it is not difficult to recognize the signs of the majority without the skills of an automobile diagnostician or minder.
Common causes for all engines
The characteristics of the motor indicated in the passport data of the car are provided under certain conditions. This is the normal filling of the cylinders with air, which is the working fluid in the internal combustion engine. This is the ability to heat it up to the desired temperature in time - to supply a certain amount of fuel of proper quality and set it on fire on time (the pressure peak for maximum efficiency should occur at the moment the piston crosses top dead center).
ICE working cycle
The loss of engine power, regardless of its design, is the result of a number of general causes. Let's start with fuel: its quality remains lottery, while the engine is tuned to a certain grade. That is, the mixture prescribed in the injection maps or the mixture specified by the carburetor settings may deviate from the ideal, and the burning rate of the mixture changes. So, if problems appeared immediately after refueling, you yourself know which way to look.
The filling of the cylinders with air is rigidly connected with the valve timing. It's enough to leave marks like bars ICE operation will be displaced: already a difference of 1 tooth can significantly reduce the motor power. Moreover, it is not necessary for the belt or chains to jump - more and more motors receive keyless pulleys, which require rigid fixation of the shafts with special devices during installation. If you do not reach the pulley, and one day it will move from a given position. And it's good if the engine simply loses traction, and does not hit the piston on the valves that did not close in time, driving them into the cylinder head.
On engines with variable valve timing, the camshafts (at least one) have the ability to shift so that when sufficient throttle response on the bottom (small phase overlap), do not lose and on the top (the camshafts are shifted "towards each other", increasing the overlap phase, which increases power at high speeds). Possible reasons why the car does not pick up speed are a failure of the VVTi control valve or problems with the phase shifter couplings. We have already discussed this issue, speaking of.
In addition, cylinder filling is tied to intake and exhaust resistance. To clog the air filter so that it loses its throughput - this must be contrived, but oil emissions through the crankcase ventilation system, especially if the piston filter is already worn out, and the oil trap is primitive, are not uncommon. On the VAZ-2106, it is not difficult to make the engine "take a sip of oil" through the crankcase ventilation, and even on fresh front wheel drive vehicles(2109, 2110, 2114) such cases are possible. At the oily air filter resistance grows sharply, hence the loss of motor thrust.
Release on carburetor cars and old diesel engines is simple, and it is enough to significantly reduce the cross-section so that the engine begins to "choke" with exhaust gases, perhaps with a powerful blow (when moving over irregularities, for example) or a canon potato - but it is at least immediately noticeable.
If the engine with electronic injection does not pull, then the catalyst gets under suspicion in this case. Overheating, the ingress of fuel due to malfunctions in the power system can cause sintering of its honeycomb. For diesel engines with particulate filters, soot becomes the main enemy: automatic filter burning on the go is ineffective, and at least a forced regeneration must be performed.
Problems with the release easily betray themselves: a muffled engine throws smoke into the intake during the next attempt to start, the sound of the engine changes, leaks immediately "creep out" (the exhaust begins to "whip" to the damaged area).
The engine must not only get the right amount of air and fuel - it must ignite on time. On a gasoline engine, an appropriate ignition timing is needed, for a diesel engine - an injection timing. Since there is no separate ignition system on modern injection engines, ignition timing problems are primarily characteristic of carburetor machines and old injection systems with a distributor (the Japanese used such systems right up to the early 2000s). Check the basic advance angle, set by the distributor, and the operation of the advance automatic devices in it (in case of malfunctions, the angle, normal at idle speed, will start to "go away" when accelerating).
A separate case is motors where the distributor is driven by a separate pulley from the timing belt (old Audi and Volkswagens). Here, when replacing the belt, the distributor pulley is set "as needed" (there are no marks on this pulley!), Forgetting that when replacing the belt, the distributor must be oriented with a cam according to the risk on the crankcase under it. After such a replacement, the car stops driving, since the ignition angles change. For diesel engines with a mechanical injection pump, the initial injection angle is set, in addition, the advance regulator works - they are checked according to the data from the repair and maintenance instructions.
On gasoline engines we also add spark plugs to the suspects: even if the engine runs normally at idle, it is not a fact that the spark plugs will work well under load when the pressure in the cylinders at the end of the compression stroke rises and the conditions for sparking become worse. It is worth putting another kit for the test: without an oscilloscope, which allows you to take the voltage curves from a working ignition system, it is difficult to determine how the plug actually behaves under load. In the illustration below, look at the peak voltages corresponding to the moment of sparking: the gap in the third cylinder is excessively increased, the spark ignites at too high a voltage, and its duration decreases (the power accumulated in the ignition coil is not enough for normal spark burning).
If we talk about compression, then under normal conditions it decreases with wear so slowly that the decrease in power occurs imperceptibly for the driver. The exception is rapidly developing breakdowns (cracks piston rings, destruction of partitions between the rings,). Simultaneously with a drop in power, idle stability will sharply drop, the final diagnosis will be unambiguously delivered by a compressor.
As for turbocharged engines, the state of the turbocharger is reflected well on their dynamics. An ideal centrifugal pump (turbocharger impeller) has a quadratic dependence of performance on rpm: as soon as the rpm drops by half, the boost pressure drops by four. Rotor wedging due to destruction or coking of bearings, burning of a "hot" impeller is a probable reason why a turbocharged machine does not pull. Here, as with compression, a pressure gauge will help out.
Reasons for the loss of power in a carburetor engine
Here it is worth immediately checking the fuel level and the operation of the fuel pump: "underfilling" the fuel immediately betrays itself under load with a loss in dynamics, shots into the carburetor. Overfilling due to a faulty locking needle of the carburetor will likewise lead to a loss of power by the engine, here black smoke and firing from the muffler will already become a characteristic feature.
The dynamics of the car is perceived better during acceleration, so that a possible reason for the "dullness" of the car can be a defect in the accelerator pump. The fact is that all carburetor systems are designed to work in static modes, while the mixture is over-depleted when speeding up. To combat this overpopulation, an accelerating pump is used: when you press the gas pedal, the diaphragm pushes a dose of gasoline through the shut-off valve into the nozzles that go into the diffusers. If the diaphragm of the accelerating pump ruptures or the spray nozzles are clogged, the acceleration of the machine will immediately deteriorate so much that it is difficult not to notice. It is not difficult to check the accelerating pump - after removing the air filter or "turtle" from the carburetor, you need to sharply press the throttle actuator: your fingers will feel resistance (the diaphragm will create pressure in the accelerating pump), and trickles of gasoline should hit the inlet from the nozzles.
In operating modes, the composition of the air-fuel mixture is set statically by a set of fuel and air jets. It is worth blowing them out, and in case of noticeable deposits, rinse them with a cleaner: even if this is not the problem, it will not be superfluous to maintain the serviceability of the main dosing system.
Does not pull the injection engine
Why doesn't the car pull when the injection systems are equipped with feedback and can self-adjust in a “closed loop”? Alas, the possibilities for self-regulation are not as wide as we would like.
The first enemy of injection systems is insufficient pressure fuel. When the fuel consumption is minimal, the correction reserve is sufficient for idling. But as soon as the engine is loaded, the correction will jump to the maximum threshold, but the injectors will still "underfill".
The pressure in the fuel rail is set by three units: the fuel pump itself, the pressure regulator and a set of filters (coarse and fine). The performance of a serviceable fuel pump several times exceeds the needs of the engine at maximum flow - this is done so that pump wear is as little as possible affecting the operation of the engine. Therefore, a fuel pressure regulator is used, which discharges "excess" fuel either immediately at the pump outlet, or from the fuel rail after the fine filter.
In the first case, the fuel rail is called drainless (16-valve VAZ engines, modern foreign cars), in the second - drain. The difference between these systems is in the location of the regulator and in its operation. On the drain ramps, the pressure regulators are controlled by the vacuum in the intake manifold, the pressure in the ramp changes depending on the load (at normal 3 bar for a VAZ at idle speed, it is 2.3-2.4 bar, take this into account when diagnosing!). The pressure is kept constant with respect to the atmosphere on non-drains and amounts to 3.5-4 bar, depending on the car model. An exception is direct injection systems, where operating pressure ranges from 20 to 70 bar.
Something else useful for you:
The resistance of the fuel filters does not affect when measuring the fuel pressure "in the plug" (the pump is forcibly switched on on the muffled engine when there is no fuel flow in the rail) and is minimal at idle. But on the other hand, under load, an excessive increase in filter resistance reduces fuel supply to the rail, which will lead to a loss of speed. Therefore, measure the pressure at idle speed and under load (for example, hanging the drive axle and braking the wheels in the engaged gear). In cases where idle speed is normal, and problems occur on the fly, it is meaningless to measure pressure only at idle speed (XX).
Checking exclusion stages:
- Remove the coarse filter (mesh at the inlet). This is a known problem in a number of cars - for example, on the second generation of "Focuses".
- Replace fine filter.
- Measure pressure under load.
- On engines with a drain ramp, squeeze or otherwise muffle the return line to exclude the influence of the fuel pressure regulator. On motors with a drainless ramp, the RTD is installed in the fuel pump module, here it is easier to temporarily install a plug washer made of polyethylene or other material that is not destroyed by gasoline under it.
- Measure the pressure again: if it has increased, then the RTD must be replaced, otherwise, the pump must be replaced.
The second reason is "underfilling" -. Even with normal filter operation, the formation of deposits on the nozzles is inevitable over time. Only the shape of the spray torch can be assessed at home by removing the ramp and turning the motor with a starter (Attention! This procedure is fire hazardous!). A clean nozzle should "dust" evenly, and not spurt or pour to the side. It is possible to evaluate the performance of injectors and compare it with the nominal one only at the stand.
Loss of dynamics is a consequence of the excessive enrichment of the mixture. The fuel pressure regulator cannot be blamed here (the pump performance, even when operating without an RTD, is not so high that the correction margin of the injection computer does not overlap the enrichment). It is much more likely that the injectors are leaking (again, it is checked at the stand) or the failure of the sensors on which the calculation of the injection time is tied.
Here the undisputed leader - the mass air flow sensor - is an accurate but sensitive device. As the mass air flow sensor is getting dirty and aging, the readings are overestimated, the car starts to consume significantly more fuel. As a result, the over-enrichment of the mixture can no longer be corrected by. But such a malfunction is immediately visible: the car will start to smoke, the candles will become overgrown with black carbon deposits. On motors with an absolute pressure sensor, the air temperature sensor is more likely to fail (here it is a separate unit, while in the mass air flow sensor it is built-in).
On vehicles with an electronic throttle, it is worth checking the operation of the servo by removing the nozzle from the throttle and allowing it to gas. The throttle should open evenly, without pauses and wedging, indicating problems with the drive gearbox or (the axle, overgrown with carbon deposits, wedges in the housing).
Video: Lost power. Loss of power
Seal
Sufficient engine power is a prerequisite for normal vehicle operation. But what to do when the diesel engine does not pull, although not "Multi-colored" smoke? Nothing - stop by our service center... But first, find out the possible theoretical reasons for this phenomenon, so as not to suspect the mechanics of "auto-cheating" costing extra money.
What is needed for a diesel engine to work "in full"
More often than not, even when there is no white, black or blue smoke, the motor does not develop its full power. This happens sometimes due to a decrease in the permeability of the coarse fuel filter in the tank of the machine, and a decrease in the permeability of the fine fuel filter. Of course, most motorists are in awe of their car and therefore, having driven exactly as much as the manufacturer indicated, they rush to change the filters in good faith.
But often automakers cannot even imagine that in diesel fuel this amount of water or dirt may be present.
Therefore, the first and foremost rule: if you want the engine to pull "to the fullest" - change the fuel filter at least after half the mileage specified by the manufacturer.
This is especially true when refueling somewhere far from large cities. However, you can visit us, and we will help not only with repair of fuel injection pump or other units, but we also modernize the fuel system, making it less vulnerable to our fuel.
To make sure that the reason for the loss of power by a diesel engine is low-quality fuel, you need to replace the factory opaque fuel pipes connecting the injection pump with the fuel filter to a transparent auto hose. After replacing the hose and fuel filter be sure to bleed the fuel system by removing excess air.
After completing all these requirements, start the engine. If the fuel filter is clogged, you will see air bubbles circulating in the transparent hose. By increasing the speed of the diesel engine, the number of bubbles will visually increase significantly.
Air bubbles in fuel system are the cause of interruptions in the operation of the motor (engine "troit"). At the same time, there is a loss of power.
What to do when the motor "troit" only at high speeds
If at medium and idle you have no complaints about work diesel engine, and when going to high revs the motor starts to "triple" (which, of course, does not allow it to work at the rated power), then it is worth thinking about:
- malfunctions of the engine gas distribution mechanism (timing);
- turbocharger malfunctions;
- loss of patency of the fuel filter (when it is literally clogged with dirt).
To find the specific cause, again, start with the fine fuel filter - it may be time to replace it. Disconnect the fuel hose from the filter fitting and lower it into a can of clean diesel fuel.
Now start the engine, and if it runs at any speed like a clock, then the reason unstable work there was just a dirty fuel fine filter. So, it's time to replace it. If the malfunction persists, try again to clean the coarse filter from dirt. And bleed the fuel system again.
If, after additional cleaning of the filters, the engine stubbornly runs at speeds above average, then check the compression. It can decrease as a result of a violation of the functionality of the valve mechanism, including due to a malfunction of the hydraulic lifters (when one of them is jammed due to dirty oil) and the cylinder-piston group.
In a word, there are plenty of reasons for the motor not operating at full power. And in order to make the right (and the lowest in price) decision, it is easier and cheaper to come to our auto center in order to forget once and for all that your diesel engine doesn’t pull. So do not put off until tomorrow what should have been done the day before yesterday - repair of injectors or engine diagnostics.
Engine does not develop full power
Decrease maximum speed More than 15% of the nominal and a large increase in the acceleration time on a dry road with a hard and smooth surface with good technical condition of the chassis mechanisms of the car indicate insufficient engine power and the need to eliminate engine malfunctions or repair it. Most of the possible causes of power loss problems can be fixed along the way without removing the engine.
More serious work related to opening the engine is performed at the station Maintenance cars.
Late or early ignition
If the engine does not develop its full power, then it is most advisable to check the ignition setting. If the ignition is too late, the engine loses throttle response and overheats. A significant decrease in power occurs due to the fact that the mixture does not have time to burn at the moment when the piston is in the TDC. The combustion of the mixture continues with the downward movement of the piston. This is evidenced by the increased heating of the exhaust pipe. It will be too hot, as part of the mixture burns out when released. Too early ignition also has a detrimental effect on the operation of the engine, when the combustible mixture ignites prematurely and the force of the gases acts against the piston, which moves towards the engine speed. At the same time, frequent and ringing metal knocks are heard in the engine, detonation may occur, the engine does not work well at low speed crankshaft, and when starting with the handle sometimes gives back blows.
Finding that power is lost due to too early or late ignition, it should be adjusted. If by adjusting the ignition timing by the methods discussed earlier at 69 e., It is not possible to achieve the desired results, then, obviously, there are malfunctions in the automatic ignition timing devices - centrifugal or vacuum regulators.
It must be remembered that the centrifugal ignition timing regulator starts working at 400-600 rpm. If, however, malfunctions arise in the centrifugal regulator - weakening of the springs or jamming of weights - this will lead to a violation of the ignition timing. When the fuziks of the regulator jam, the ignition moment at both low and high speeds of the crankshaft will remain the same. Meanwhile, for high speeds of rotation of the crankshaft, the ignition moment should be earlier.
Rice. 1. Ignition distributor of the Moskvich car (with the cover removed, the rotor, the octane corrector and the vacuum regulator): a - ignition distribution housing; b - drive roller with weights
Late ignition at high crankshaft speeds causes a decrease in power and increases fuel consumption. If the regulator springs have weakened and the weights diverge completely, then even at low crankshaft speeds, a large ignition advance will occur, which will also lead to excessive fuel consumption and a decrease in power. The operation of the centrifugal ignition timing regulator can be checked in the following simple way.
Without removing the ignition breaker-distributor (Fig. 1) from the engine, pull the breaker lever and turn the cam by hand in the direction of rotation of the roller to failure. The weights will open at the same time. Then release the cam, and it will return to its original position under the action of the weight springs. If a jam is found, it is necessary to remove it and replace the weakened springs.
It is known that a centrifugal regulator regulates the ignition moment only depending on the crankshaft speed. But on the way, the car has to move both on a flat road and on a road with uphills. Suppose that when driving at a constant speed both on a flat road and on an uphill road, the centrifugal regulator will give only the same ignition timing. While when driving on a road with uphills, the engine load and opening of the throttle valve are much greater, therefore, the ignition advance should be less than when driving on a flat road at the same speed. The ignition timing when changing the throttle valve opening (engine load) is performed by the vacuum regulator (Fig. 2).
It may have the following malfunctions: loss of spring elasticity, air leakage into the spring cavity, wear or damage to the diaphragm located in the middle of the housing of the vacuum ignition timing regulator, jamming of the ball bearing and the breaker-distributor panel.
When the spring of the vacuum regulator is weakened at low and medium loads, the ignition timing increases. If air is sucked into the cavity where the spring is located (if the diaphragm is damaged), then the ignition timing will decrease at low loads. If too much air is sucked in, the vacuum ignition timing controller will not work at all.
Rice. 2. Scheme of operation of the vacuum ignition timing controller: a - when the load is reduced; b- with increasing load
On the way, the serviceability of the vacuum regulator can be checked by shaking the breaker panel on the bearing.
In this case, it is necessary to check and determine whether there is an increase in the gap between the panel pin and the rod of the diaphragm of the vacuum ignition timing regulator and whether the rod itself does not jump off.
If you create a vacuum in the tube of the vacuum regulator disconnected from the carburetor pipe, then if it is in good condition, the breaker panel should turn in the opposite direction to the rotation of the cam.
Insufficient filling of the cylinders with the working mixture
Having found that the ignition timing controllers are in good working order and the ignition is set correctly, the reason for the decrease in engine power must be sought in the insufficient filling of the cylinders with the working mixture. This can be caused by a sticking of the throttle valve on the axle (its incomplete opening). To do this, check the throttle valve drive, if necessary, remove the jam. Then you need to make sure that the air filter is working. If it is dirty, it is necessary to replace the dry filter element, and on cars where the filter is with an oil bath, disassemble, rinse it and, if necessary, change the oil. It is advisable to check the serviceability of the valves and springs of the gas distribution mechanism. In case of violation of clearances, breakage of valve springs, replace the broken springs and adjust the clearance.
Insufficient filling of the cylinders with the working mixture can be due to the sticking of the needle valve of the float chamber, the use of fuel with an inappropriate octane number, with a large deposition of tar and coke in the intake manifold, as well as with a large soot in the engine cylinders.
A common cause of reduced engine power is a lean mixture in the cylinders.
The reasons for the formation of a lean working mixture are as follows:
- clogging of jets and channels in the carburetor, contamination of fuel lines, freezing of water in the power system. In this case, it is necessary to blow through the jets, channels and contaminated fuel lines using a pump to inflate the tires of the wheels, and if necessary, clean them with copper wire, disassembling the carburetor;
- seized valves fuel pump, a clogged strainer, or a slight break in the diaphragm. In this case, first, the seizure of the fuel pump valves is eliminated, the mesh filter is washed, and the broken diaphragm is replaced or temporarily restored by the method described in Sec. "There is no fuel supply";
- air leaks at the joints of the carburetor parts, the carburetor flange with the intake manifold, the intake pipe flanges with the cylinder block due to loosening of the fasteners, as well as damage to the gaskets. The suction point can be detected with soapy water. A window will form in the soap suds at the supposed suction site. Air leakage is eliminated by tightening nuts or bolts, as well as replacing the corresponding gaskets;
- wear of the fuel pump drive lever, clogging of the air hole that communicates the fuel tank to the atmosphere, jamming of the air damper. Eliminate these malfunctions as follows: replace the faulty parts of the fuel pump with new ones, clean the air hole in the plug, check and, if necessary, adjust the length of the carburetor choke control cable.
The engine may not develop full power due to decreased compression in the cylinders. It is necessary to restore normal compression in the engine cylinders at the service station.
The tractive effort developed on the engine crankshaft is transmitted to the drive wheels through the whole system of vehicle units (clutch, gearbox, cardan transmission, main gear), from technical condition which depends on the efficiency of operation and the safety of the vehicle.
During operation passenger cars various malfunctions may occur in these units.
To determine and eliminate the causes of malfunctions that have arisen in these units, testing, fastening and adjustment work is carried out, and, if necessary, their repair at a service station.
Consider the main causes of malfunctions of transmission units and possible ways their elimination. Let's start with the clutch.
Typical signs of a clutch malfunction are:
- slipping,
- incomplete engagement (clutch "leads"),
- a sharp turn on,
- noise and knocking in the clutch.
TO Category: - Automotive malfunctions
Sometimes drivers say: the engine pulls poorly, the car does not develop maximum speed. Where to look for reasons? There may be several of them:
- severe overheating of the engine;
- faulty ignition system: faulty ignition setting (ignition too early or late); there was a seizure of the centrifugal ignition timing regulator; there is a malfunction in the vacuum ignition timing controller;
- insufficient filling of the cylinders with the working mixture;
- interruptions in engine operation;
- drop in compression in the cylinders;
- entering the cylinders of a poor working mixture.
If the engine does not develop its full power, then
It is most advisable to check the serviceability of the ignition system. Note that too late ignition, the engine loses throttle response and overheats. A significant decrease in power occurs due to the fact that the mixture does not have time to burn at the moment when the piston is in. m. t. The combustion of the mixture continues when the piston moves down, it is easy to determine by touching the exhaust manifold with your hand. It will be too hot, as part of the mixture burns out when released. Too early ignition also has a detrimental effect on the operation of the engine, when the combustible mixture ignites prematurely and the force of the gases acts against the piston, which moves towards the. m. t. At the same time, frequent and resonant metal knocks are heard in the engine, the engine is prone to fuel detonation, does not work well at low speeds, and sometimes gives back blows when started with a handle.
If you find that power is lost due to too early or late ignition, adjust it. If by adjusting the ignition timing it is not possible to achieve the desired results, therefore, there are malfunctions in the automatic ignition timing devices; centrifugal or vacuum regulators.
It must be remembered that the centrifugal regulator adjusts the ignition timing only depending on the engine speed. It usually starts at 400-600 rpm. If malfunctions occur in the centrifugal regulator (weakening of springs or sticking of weights), this will lead to a violation of the ignition timing. When the weights of the regulator are seized, the ignition moment will remain the same at both low and high speeds. Meanwhile, for high revs, the ignition moment should be earlier.
Late ignition at high revs will cause a decrease in power and increase fuel consumption. If the springs of the regulator are weakened and the weights disperse completely, then even at low speeds there will be a large ignition advance, which will also lead to excessive consumption of fuel and a decrease in power. Usually, the serviceability of the centrifugal regulator is checked using a synchronograph.
But, as a rule, there are no instruments on the way. Nevertheless, the operation of the centrifugal regulator can still be checked. How it's done? Without removing the distributor from the engine, you need to move the breaker lever and turn the cam by hand in the direction of rotation of the roller to failure. The weights diverge. Release the cam and it will return to its original position under the force of the weight springs. If jamming is found, then it is necessary to eliminate it, and replace the weakened springs with new ones.
From what has been said it is clear that the centrifugal regulator regulates the ignition timing only depending on the number of revolutions. But on the way, the car has to move on a different road - flat and with ups. Let us assume that when driving at a constant speed both on a flat road and on an uphill road, the centrifugal regulator will give only the same ignition timing. While the engine load and throttle opening are much greater when driving on the road with an uphill, the ignition advance should be less than on a flat road when driving at the same speed. The ignition timing when the throttle opening (engine load) is changed is performed by the vacuum regulator. It may contain the following malfunctions:
- loss of spring elasticity;
- air leaks into the plane of the spring;
- seizure of the ball bearing of the breaker panel.
When the spring of the vacuum regulator is weakened, at low and medium loads, the ignition timing increases. If air is sucked into the cavity where the spring is located (if the diaphragm is damaged), then the ignition timing will decrease at low loads. If too much air is sucked in, the vacuum regulator does not work at all. The vacuum regulator can also fail if the ball bearing of the breaker panel is seized.
Like a centrifugal one, a vacuum regulator is usually checked for serviceability using a synchronograph. On the way, it can be checked in the simplest way: shake the breaker panel on the bearing and make sure there is no excessive gap, and also determine if there is an increase in the gap between the panel pin and the diaphragm rod, whether the rod itself does not jump off.
If you create a vacuum in the tube of the vacuum regulator disconnected from the carburetor, then if it is in good condition, the interrupter panel should turn in the opposite direction of the cam rotation. Having found that both timing controllers are in good order and the ignition is set correctly, the reason for the decrease in power must be sought in the insufficient filling of the cylinders with the working mixture. This can be caused by a sticking of the throttle valve on the axle (incomplete opening of it). It is necessary to check the throttle valve drive and, if necessary, remove the jam, clean the axle. Then make sure the air filter is working properly. If it is dirty, disassemble, flush and, if necessary, change the oil. It is advisable to check the serviceability of the valves and springs of the gas distribution mechanism; in case of violation of the gap size or breakage (loss of elasticity) of the valve springs, weak and broken springs should be replaced, the gap should be adjusted.
Insufficient filling of the cylinders with the working mixture can occur when the needle valve of the float chamber is jammed, a faulty muffler, the use of an inappropriate fuel grade, as well as in the case of large deposits of tar and coke in the intake manifold.
A common cause of incomplete engine power is a lean mixture in the cylinders. The reasons for the formation of a lean mixture:
- the jets and channels in the carburetor are clogged, the fuel lines in the power system are contaminated (freezing of water). Flush and blow out nozzles and channels, blow out contaminated fuel pipes, and if necessary, clean them with wire;
- jamming of the fuel pump valves or clogging of the sump mesh, a small break in the diaphragm. First, eliminate the sticking of the fuel pump valves, rinse the filter element and the mesh, and replace the torn diaphragm with a new one, or restore the old diaphragm to work in the manner described earlier;
- air leaks at the joints of the carburetor parts, the carburetor flange with the intake manifold, the intake pipe flanges with the cylinder block due to loosening of the fasteners, as well as damage to the gaskets. You can find the place of suction with a match or soap suds. The flame of a match, brought up to the intended place of suction, deflects towards the gap, and a window forms in the soap suds. Air leakage is eliminated by tightening nuts or bolts, as well as replacing the corresponding gaskets;
- wear of the fuel pump drive lever, clogging of the air holes in the filler plug fuel tank, jamming of the air damper. These defects are eliminated as follows: faulty parts of the fuel pump are replaced with new ones, the air holes of the plug are cleaned, the length of the air damper control cable is checked and, if necessary, adjusted. Comparatively often, the reason for a decrease in engine power is a drop in compression in the cylinders.
