10 Reasons Why Your Car Engine Is Losing Power

Your car’s engine produces power through combustion which happens through a mix of air and fuel. Sometimes, due to several reasons, the rate of this combustion slows down and your engine loses power.

In this post, I’ll be taking you through the top reasons why your car engine is losing power and what you need to do to restore its performance. 

car engine losing power

1. Air Filter

We’ll start right off the bat with the air filter. This is something super simple to fix but you can get air filters that clog up with time as debris gets in there. And so, this can cause a pumping loss for your engine. Your engine has to work harder to bring in the air because that filter is clogged up and it may not be able to pull in much air. As a result, you can’t make as much power.

car engine losing power due to clogged air filter

2. Throttle Cable

This relates to cars with mechanical throttle cables. This cable can loosen over time. It’s a simple fix to just re-tighten it. It can stretch over time and as a result, you may not be able to open your throttle all the way. And of course, if you can’t open your throttle all the way, you’re not gonna be able to get in all of that air, and therefore, you’re gonna be making less power.

car engine losing power - throttle cable

3. Catalytic Converter

Now let’s move to the exhaust side of it. The air of course has to move through that engine nicely on both sides. So your catalytic converter can get clogged up over time from rich air-fuel mixtures, having the engine cold, and things like that.

You can have a deep dive into the signs of a bad catalytic converter and how you can troubleshoot them. Exhaust particulates can build up there. And the same thing can happen with your muffler – which is the next thing we’re gonna be looking at.

car engine losing power while accelerating - catalytic converter

4. Muffler

You can have deposits build up in your muffler, reducing and restricting airflow through your exhaust causing additional pumping losses.

Also, as these mufflers age, some of them can even rust, and that internal piping can kind of fall apart. And as a result, it may not act as efficiently as it once did. You can read up on this post on how to clean a clogged muffler to gain insight into how to effectively solve muffler issues.

car engine losing power in motion

5. Fuel Injectors

As a result of heat soak, which is caused by using poor fuel, these fuel injectors can get clogged up with time from particulates within the combustion chamber. And of course, if they’re clogged up, it can cause misfiring, and can also cause your air-fuel ratios to be thrown off. This will cause your car to make less power.

car engine losing power

6. Fuel Pump

The fuel pump can wear out over time. And so, you’ll notice this because, on the low end, they’ll work just fine and they’ll be able to supply fuel. And then, as you get into those higher RPMs with high loads, or in higher loads for a long duration, the fuel pump may start to struggle and may not be able to meet that fuel demand.

And so, you’ll notice that if you’re going up hills or if you’re in that high RPM scenario and you’re struggling to get power, it may be a failing fuel pump that can’t quite deliver that fuel quantity anymore.

car engine losing power - fuel pump

Related Post: Engine Knock on Startup Then Goes Away

7. Piston Rings

Another reason why your engine could be losing power is as a result of your piston ring wearing down. This is one of those things that’s a bit more challenging to replace. This is because it requires stripping down the entire engine to get to those piston rings in order to replace them if you need to do that. It’s basically a whole engine rebuild.

These piston rings will wear against the wall over time. And as they wear, you can have increased blow-by which makes you get less compression from your car.

So one thing you can really do to help prevent your piston rings from wearing is just to make sure you stay on top of your oil change intervals to make sure that those piston rings are well lubricated against your cylinder walls.

car engine losing power due to piston rings

8. Valve Deposits

This is an issue of deposits in your intake valves, specifically. This plays a big role in how much power you can create.

Over time, especially in direct injection engines that do not have port injection where fuel is being sprayed over the intake valve to constantly clean it off, and where you have your positive crankcase ventilation system sending oil back through your intake and then onto your intake valves, it can start to build up those deposits on it.

So this can cause a lack of compression because that intake valve may not be able to properly sit in that valve seat and it can also cause backfiring. As you’re compressing back in, you may be able to squeeze some of that air-fuel past that intake valve. As a result, you’re not gonna have good compression.

You could also have backfiring if that combustion is able to exit past that valve. And of course, it also plays a role with your air and fuel as it can cause an additional restriction for airflow to come by, and can mess with your air-fuel ratio.

cause of car engine losing power while accelerating - valve deposits

Related Post: Spoon Engine

9. Spark Plugs

Your spark plugs can get fouled up with time from fuel, oil, and carbon deposits. This can cause an inconsistent spark and of course, misfiring. You need your spark plugs in good working order in order to make peak power.

car engine losing power due to bad spark plugs

10. Knocks

So as you start to have these deposits forming within your cylinder walls and on your pistons, the deposits can heat up and cause a knock. 

If you do start to have a knock in your engine, the first thing your engine is gonna want to do is retard the timing. This means that it’ll fire that spark plug later. If it needs to do that to compensate and to make sure you don’t have a knock, your engine is going to be losing power.


One of the most worrying issues any car owner can have is an engine that keeps losing power while you’re driving. This just means that you can’t enjoy the full potential of your car’s performance. However, as you have seen from the list of reasons stated above, this is not something that cannot be easily fixed by you or an auto-mechanic depending on the cause of the power loss.