Hello today i will tell you the reason why your car engines lose power over the time. You would have noticed the change while driving a new car and an old car. As the car gets older you would feel the power lag.

There are Four major things gasoline engine require to generate power.


If the air inflow in your engine is not consistent, adequate power will not be generated.

Dirty Airfilter

If you have a clogged air filter the engine wont receive enough air into engine. The engine needs to work hard to pull air in and generate less power, because low air low power. Though it is an easy fix you have to just check the air filter under the hood which is easily accessible. Either clean it or replace it.

Throttle Cable

The cable connected to your accelerator pedal is the throttle cable. It loosens or get stretched over the time. If you have a loose throttle cable you will not be able to pull enough air with little press of your pedal. stretched cable will not allow you to open the throttle valve completely. Both will cause of less intake of air which means less power.

Exhaust Restrictions

Emitting exhaust gas is must for the engine, because whats goes in should come out. A blockage in the exhaust pipe in either end will reduce the airflow and reduce the performance. Catalytic converters can clog up the engine with improper air/fuel mixture. Muffler can also get rusted because of which airflow can be affected.

Valvetrain Wear

Over the time the valves components wear, this can be reduced by proper changing of engine oil. But the in case of self-adjusting valves wear are less comparatively. The components used for valve opening and closing wear quickly, which affects the valve timing and valve lift. Less valve lift and duration means low air intake which will result in low power.


Fuel Injector

These can also be clogged up due to some heat soak or poor fuel deposits in the fuel injector over the time. This can cause misfires of the fuel injector resulting in low power generation.

Fuel Pump

Fuel pump also wear out over time. Even after wear the fuel pump will be able to pump fuel at low pressure, but it may struggle with high pressure pumping for longer durations. so under high pressure condition it will not pump required fuel. If you notice a power lag on uphill it could be because of wearing fuel pump.


Compression issues are more often seen in older cars. It is caused because of the worn off metal components. Fixing this is not easy.

Worn Piston Rings

Piston does the major work of compression, these piston rings will wear over the time which increases blow-by and results to less compression. Some air will escape while the piston is travelling upwards. To avoid wearing of piston rings, regular oil change is advisable.

Carbon Deposits On Intake Valves/Valve Seats

Carbon deposits on valve or valve seat, will prevent the valve from closing completely, If the valve does not close completely the air would escape the compression stroke, lowering the compression ratio. This could also result in backfiring as the air/fuel mixture travels past the intake valve during combustion. This will also affect the airflow and air-fuel ratios.


Inconsistent Spark and misfiring can happen if your spark plug is filled with fuel, oil and carbon deposit. Maintaining clean plugs ensures that the spark part of the equation doesn’t result in a loss of power.


The deposits on the cylinder wall creates hot spots. These hot sports will ignite on its own using the air-fuel mixture. So you have to ignition one from spark plug and another by hot spots. Both will collide and create a knocking sound which you hear.