Engine power has dropped – what could be the problem?

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If you notice that the car accelerates poorly and works unsteadily at high speeds, you should pay attention to the main engine operation systems. The cause of the problems will not necessarily be hidden in a destroyed cylinder block or a non-working cylinder head. It is possible that the causes of power loss are simpler and less expensive to repair. If you are not ready to look for companies that buy junk cars without titles in Memphis or another American city, let’s look at the reasons why engine power may be reduced.

The Main Reasons For Reducing Engine Power

A decrease in engine power is not always caused by serious breakdowns in the automotive system. In some cases, it is enough to carry out a technical inspection and inexpensive repairs or cleaning. Among the most likely causes of reduced engine power:

  • changes and breakdowns in the fuel supply system;
  • problems with air supply to the engine;
  • a non-working sensor in one of the motor systems;
  • failure of one of the cylinders for a certain reason;
  • problems with fuel ignition – candles, wires, coils;
  • improper preparation of the fuel mixture;
  • violation of the optimal compression of the engine.

All these troubles can happen to literally any motor at any mileage. So it’s worth taking a closer look at them so as not to miss the beginning of problems. In this case, you can save on repairs.

Fuel And Air Supply System

One of the most common causes of engine power loss is fuel delivery problems. In this case, the fuel pressure at the injector rail or at the moment of injection into the combustion chamber drops. This leads to improper mixing of the air-fuel mixture, due to which the engine cannot burn gasoline or diesel fuel properly.

There may also be problems with the air supply. Dirty air and the wrong amount of it cause the car to lose optimal power in a certain rev range. Such problems should not be observed for a long time. Lack of repair for a long period can greatly worsen the condition of the car.

Problems can be related to clogged fuel and air filters, leaky fuel supply systems, clogged pipes, and deformed gasoline or air supply elements to the engine. Also, problems can be caused by the MAF sensor, which regulates the preparation of the mixture by sending air consumption data to the computer.

Lambda Probe And Catalyst:The Main Enemies Of Car Power

In a new car, the catalyst performs an extremely important task. It cleans exhaust fumes from various kinds of impurities, ultimately improving the environmental impact of the car on the environment. But over time, this device is destroyed and clogged. As a result, the air from the engine cannot freely escape through the exhaust pipe. For this reason, the motor literally cannot breathe normally, it reduces power and generally works unevenly.

Also, problems with the engine can be caused by a breakdown of the oxygen sensor – the lambda probe. This sensor is connected to the catalyst and measures the amount of oxygen that passes through a specific element of the exhaust gas treatment system. If the sensor is broken, it sends incorrect data to the computer, and the ECU in turn increases or decreases the engine speed to even out the sensor readings. This element is checked during diagnostics, usually, it gives a Check Engine signal in the event of a breakdown.

Breakdowns In The Cylinder Head

If the mileage of your car is high enough, and you notice changes in the operation of the engine, you should make sure that there are no problems with the motor head. Most often there are problems with valve seals. The valves themselves, valve seats, and other elements may also be worn out. Problems can even arise due to excessive oil deposits on the seats and the valves themselves since in this case the valve simply will not close and will not provide proper compression.

All problems are due to compression changes. The cylinder head can be repaired. Overheated and deformed cylinder heads cannot be repaired.

Problems In The Cylinder Block

Compression can drop not only due to problems with the head. There are several types of rings installed on pistons in an automobile engine. Oil scraper rings do not allow oil to enter the combustion chamber and burn out. And compression rings serve to maintain compression in the chamber. If the compression rings are worn out and cease to perform their tasks, the compression in a particular cylinder drops. This will lead to the less efficient operation of this cylinder and a drop in engine power as a whole. Over time, the cylinder will stop working altogether.

Engine Sensors

There are several sensors on the throttle valve. Also, several more sensors measure engine performance and affect the operation of the power unit. In different cars, their influence will affect differently. For example, the failure of certain sensors can simply put the engine into emergency mode, due to which the ECU will immediately programmatically reduce power and limit the engine speed.

But most often the problem is related to other sensors:

  • MAP (it fails quite rarely, but can still cause problems with creating the correct air-fuel mixture);
  • TP (on classic injection motors, this sensor sends information about the position of the damper to the ECU so that the computer can control the speed in different modes);
  • IAC (often problems are associated with the idle speed controller, which regulates the speed in the free mode of the engine).

However, other sensors can also cause problems. The loss of motor power is often associated with the most unpredictable problems with electronics. For example, the signal from one of the sensors may be lost due to broken wiring, and the ECU perceives this as a reason to put the engine into emergency mode. In such cases, computer diagnostics will help.


We have listed the most common causes of a weakened engine, in fact, there are more of them. If the engine power has dropped, then it is better to check with specialists. With the help of competent diagnostics, you will quickly find the problem and fix it. If you want to get rid of an unwanted car that no longer satisfies you, we recommend that you contact JunkCarsUs. The company buys cars after accidents, drowning, and fires without titles on attractive terms with no hidden fees.