The situation when the car ceases to please the rapid reaction to the gas pedal is familiar to every driver. Yesterday the car quickly started from traffic lights, and today there is a feeling of lethargy, failures and reluctance of the engine to spin above 3000 rpm. Such behaviour powertrain It is not only annoying, but can also be a harbinger of a serious breakdown that requires immediate intervention.
The loss of power often occurs gradually, and the driver gets used to the deterioration of dynamics, considering this the norm of aging of the car. However, 80% of cases combustion-engine It is able to return to its former speed after a competent diagnosis. The main reasons lie in the violation of the proportions of the fuel-air mixture, problems with spark formation or difficult exhaust of exhaust gases.
In this article, we will discuss in detail the mechanical and electronic aspects of the motor. You will learn how to independently conduct an initial check of the engine life support systems and understand when it is time to go to the service. Reducing compression in cylinders below 10 atmospheres is a critical indicator requiring major repairs. Don’t ignore the first symptoms, as ignoring the problem can lead to costly recovery.
Problems with air supply system and fuel
The engine works as a pump that sucks in air and fuel. If there's a barrier at the entrance, capacity It inevitably falls. The most common but often overlooked cause is a polluted air filter. Dust, down and dirt clog the pores of the filter element, creating resistance to the airflow. The engine begins to “choke”, especially with sharp acceleration.
The second important element is the fuel system. A clogged fuel filter or contaminated injectors disrupt the spraying of gasoline. Instead of a fine mist that burns instantly, large droplets fall into the cylinders, burning slowly and inefficiently. This leads to the fact that the car twitches during acceleration and poorly holds idle turns.
- 🔧 Check the condition of the air filter: if it is black or gray, it should be replaced.
- ⛽ Estimate the pressure in the fuel ramp using a pressure gauge (the norm depends on the model of the car).
- 💧 Use quality additives to clean the injector at every second refill.
- 🛢️ Change the fuel filter strictly according to the regulations, without waiting for symptoms.
☑️ Diagnostics of intake systems
Particular attention should be paid to the throttle. On modern cars with electronic throttle control (e-throttle) oily carbon shall accumulate on the walls of the channel and the valve itself. This garlic reduces the cross section of the channel and disrupts the mechanism. As a result, the engine control unit (EBOU) obtains incorrect data on the position of the valve and adjusts the mixture towards depletion.
⚠️ Note: When cleaning the throttle on electronically controlled vehicles after removing the battery terminal, a procedure for adapting the throttle through a diagnostic scanner may be required.
Ignition system malfunction
To ignite the mixture, a powerful and timely spark is needed. If the ignition system fails, the fuel does not burn completely, but is thrown into the exhaust system. This causes three-engines to fail when one or more cylinders stop working. The car in this state is not just slowly accelerating, but vibrating and losing traction at low revs.
The first to hit are spark plugs. Coar on the electrodes, increased gap or breakdown of the insulator prevent the formation of a spark. Also often to blame ignition coils or high-voltage wires (on old cars). Cracks on the wires lead to a leak of current, especially in wet weather, when the spark "goes away" on the mass of the engine.
Diagnostics of the ignition system requires a consistent approach. Visual inspection of candles is often not enough, as they may look normal on singles, but punch under load. Using a motor tester or oscilloscope allows you to see the shape of the spark and the breakdown energy, which gives an accurate picture of the health of the system.
Turn the candles and examine their color. Black nagar indicates a rich mixture, white - about poor, and red plaque indicates additives in fuel, which can be conductive.
- 🕯️ Replace spark plugs every 30-40 thousand kilometers (for conventional) or 60-100 thousand (for platinum / iridium).
- ⚡ Check the high-voltage wires for breakdowns in the dark - sparks will be visible.
- 🔌 Use only original coils or proven analogues, as cheap ones can overheat.
Effect of exhaust system on dynamics
Few people think that the exhaust system is not just a pipe for gas removal, but a complex aerodynamic path. If something interferes with the gas output, a backpressure is created. The piston group has to expend enormous energy pushing the exhaust gases out instead of pushing the car forward. This phenomenon is called a “strangled engine”.
The main culprit here is the catalytic converter. Over time, its honeycombs become clogged with soot or destroyed, turning into a dense plug. The engine stalls at high speeds, there is a hum and smell of hydrogen sulfide. In some cases, the catalyst is cut out, but this requires reflashing the ECU to remove errors on the lambda probes.
It is also worth checking the condition of the silencer. The internal partitions can come off and block the gases. Diagnosis is simple: temporarily remove the oxygen sensor before the catalyst or disconnect the receiving tube. If the dynamics improve dramatically, the problem is precisely in the “output”.
| Symptoms. | Possible cause of exhaust | Method of verification |
|---|---|---|
| The buzzing under the car | Catalyst cell breakdown | Hearing listening, endoscopy |
| Power drop above 4,000 rpm | Clogged catalyst | Manometer backpressure measurement |
| Cotton in a silencer | Fuel failure, ignition failures | Diagnosis of candles and coils |
| Whistling during acceleration | Exhaust system breakdown | Visual inspection for leaks |
Can I drive with a catalyst knocked out?
Technically, it is possible, the engine will become more powerful and economical. However, the ecological class will decrease, there will be an unpleasant smell, and the second lambda probe will emit an error that will have to be software turned off (Euro-2).
Electronics and sensors: hidden enemies
The modern car is controlled by a computer that relies on readings from dozens of sensors. If one of them is lying, EBOU Puts the engine into emergency mode or simply prepares the wrong mixture. Most often, the dynamics are spoiled by a mass air flow sensor (MMRV) and a throttle position sensor (DMP).
DMRV measures the amount of incoming air. If it is contaminated or faulty, the computer thinks there is less air than it actually is and pours less fuel. The mixture becomes poor, the machine becomes dumb. The DPD tells the computer how hard you pressed the gas. When the tracks wear, the effect of a “floating” signal occurs, and the thrust disappears in jerks.
Another important element is the knock sensor. When it malfunctions, the control unit, fearing the destruction of the engine, artificially delays the angle of ignition ahead. The engine becomes "sluggish" and does not respond well to the accelerator pedal. Diagnosis of these nodes is possible only with the help of a scanner that reads the parameters in real time.
Sensor error does not always light up on the instrument panel (Check Engine). Often the parameters are beyond the norm, but do not reach the criticality threshold for the lamp to turn on, although the dynamics are already suffering.
Mechanical problems of the engine
If all systems are in order, but the car still does not go, it is worth looking inside the engine. Wear of the cylinder piston group (CPG) leads to a drop in compression. The gases break into the crankcase instead of pushing the piston. It is a natural aging process, but it can be accelerated by overheating or oil starvation.
Gas distribution phases also play a key role. If the belt or timing chain is stretched, or was installed incorrectly during repair, the valves open at the wrong time. This disrupts cylinder filling and purging. In some cases, adjustment of the thermal gaps of the valves is required if the design does not provide for hydraulic compensators.
It's important to note the status oil-cap and piston rings. The occurrence of rings leads to theft of oil and coking rings, which also reduces compression. Diagnostics of mechanics require measurement of compression and possibly endoscopy of cylinders through candle holes.
⚠️ Note: If you added a little oil to the cylinder and the pressure increased, then the piston rings are worn out. If the pressure has not changed, the problem is in the valves or gasket of the HBC.
Transmission and clutch
It happens that the engine roars, the speeds grow, and the car accelerates reluctantly. In this case, the problem is not the motor, but the transmission of torque to the wheels. On cars with manual transmission (MKP) often to blame clutch. The disk is worn and slips without transferring all the power.
On "automatics" and variators, the causes may be in a low level of transmission fluid, wear of frictions or a malfunction of the hydraulic transformer. Old oil loses its properties and the box cannot effectively transfer force. It is also worth checking the brake system - the jammed caliper will constantly brake the wheel, creating the feeling of a heavy car.
- 🚗 Check if one of the discs warms more than others after the trip (a sign of a jammed caliper).
- 🔄 Replace the oil in the gearbox if the mileage from the last replacement exceeds 60,000. km.
- 🏁 Conduct a clutch test: turn on 3-4 gears at low speed and sharply press the gas. If the speed is not fast, the speed is not fast.
How to check the clutch without disassembly?
Turn on the 4th or 5th gear at a speed of about 40-50 km / h and sharply press the gas pedal into the floor. If the engine speeds increase sharply, and acceleration is sluggish - the clutch disc is worn out and requires replacement.
Frequently Asked Questions (FAQ)
Why does the car only get cold enough?
This may be due to a malfunction of the coolant temperature sensor (CTZ). If it shows that the engine is already hot, the ECU does not give a command to enrich the mixture for warming up. Also, the reason may be in the air sucking through cracks in the pipes, which are cold compressed, and expand when heated.
Could bad gasoline cause power loss?
Absolutely. A low octane number causes detonation, and the knock sensor corrects the ignition angle, reducing power. Also in bad gasoline there may be impurities of water or resins, which clog the nozzles and filter, disrupting the fuel supply.
Does air conditioning affect the acceleration dynamics?
Yes, the air conditioner on takes some of the engine power through the compressor. On low-power engines (up to 100 hp), this can be noticeable, especially when starting from a standstill or overtaking. Usually the ECU itself compensates for this, slightly raising the idle speed.
What to do if the Check Engine is on and the car is not pulling?
The error code must be read using the OBDII scanner. If the error is due to ignition failures (e.g., P0300-P0304), further driving may destroy the catalyst. It is better to reach the service at low speeds or call a tow truck.