When the engine is warm, it may lose power for a variety of reasons. Because of faulty mass airflow sensors, faulty coolant temperature sensors, a malfunctioning gas pump, or air leaks, this problem is most common in gasoline-powered vehicles.
A faulty high pressure pump is the most prevalent cause of engine power loss in diesel engines while they are heated.
Knowing the combustion conditions of the fuel helps explain why engines lose power when they get hot, especially in petrol cars. Because the air is denser at low temperatures, there is more air per cubic meter.
Because its bulk is reduced by heat, the car chokes and its engine power diminishes. To a large extent, this is also true of gasoline-powered vehicles in general.
When the engine is hot, the combustion of the fuel is not responsible for the loss of power. Look at the fuel system and ignition for that.
What are the reasons for engine power loss when hot?
One of the primary reasons engines lose power as they warm up is due to variations in the operating settings of separate components. Power is lost due to weak air fuel combination caused by malfunctioning sensors, ignition module, fuel pump, distributor and high voltage.
When the engine gets warm, it loses power for a variety of reasons, including faulty mass airflow sensors and coolant temperature sensors. When the engine is heated, there are other things that can cause power loss if they aren’t performing properly.
- A bad MAP sensor. Like in the care of the mass airflow sensor, when the MAP sensor fails, it can give incorrect information to the electronic control unit (ECU) especially when this sensor is hot. Thus, it is better to check this sensor in this case.
- Heated throttle valve. Turning off the throttle heating in summer is important for cars where there is a throttle heating. Preheating overheats the air and there will be a weak mixture.
- Bad or failing gasoline pump. The fuel pump doesn’t need to be defective. First and foremost it is good to have sufficient fuel in the tank to allow proper cooling of the fuel tank because when it is overheated, the pump will not work properly. Also, you can also check it by removing it, it can accumulate dirt. After cleaning it should be ok. But if this does not solve the problem, consider replacing the pump.
- Air leaks in the intake manifold. In this case, the air mass flow sensor and the MAP sensor will send false information to the ECU, which will create a weak mixture. Cracks through which extra air is sucked are most often formed on the pipes.
- Steam-air. It is formed when gasoline boils in the fuel line. The solution depends on the engine design. The main thing is to find a place where this happens and insulate that hot part where gasoline boils.
- The ignition module. This module overheats because of the accumulation of dirt and can cause the engine to lose power when warm. It requires cleaning along with the engine itself.
- Failing fuel pressure regulator. Sometimes, when it overheats, it starts to fail. If that happens, you need to check the pressure in the fuel ramp and check the regulator.
- Bad catalytic converter or oxygen sensor. If the catalytic converter is clogged that is a sign of a power loss to the engine when it heats up. The first thing you can do is to remove the catalytic converter and clean it, it should be enough to solve the problem. However, if this doesn’t solve it then you need to change de catalytic converter. Also, a failing oxygen sensor can lead to poor engine power. Check it with an OBD scanner
- Small gaps on valves. Valve clearance is reduced when the engine is running, which leads to overheating and a loss of power for a warmed engine. If the valve is overstretched, it may stop closing
- A failing turbocharger. If for some reason, lubricant does not fit the turbo bearings, it can jam at high speeds, and at high temperatures.
- A bad or failing mass airflow sensor. One of the most common reasons why the engine loses power when hot is the malfunctioning of this part. When it not functioning correctly, it reads incorrectly the actually passing air, due to which less fuel is supplied and a weak mixture is formed. The first thing to try is to clean the MAF sensor, if this does not work, then replace it.
- Bad coolant temperature sensor. When this sensor is hot, a failing coolant sensor generates an excessive temperature for the coolant and starts to add less fuel, meaning the engine will suffer a power loss when it is hot, so it’s ok to check this sensor and the MAF sensor first when dealing with an engine power loss.
A faulty high pressure pump is the most common cause of power loss in diesel engines. High-pressure pumps might overheat because the plunger pairs wear out. The inability to start the vehicle can also be a sign of a malfunctioning high pressure pump.
When the engine is operating at its optimal temperature, you can do a water test to ensure the pump is working properly. It is likely that the pump is about to fail if the car starts properly. Changing the plunger pairs or replacing the pump is an option.