Engine Loosing Power? – Here Are Some Of The Top Reasons Why


Is your engine loosing power? Here are a few reason why that could be possible

So your car has been misbehaving for the last few days. You put your foot down maybe to execute an overtake maneuver but the car just does not pick speed as you are used to.

Loss of power in a car can be indicative of minor issues that can easily be fixed however more often than not loss of power issues will cost you a lot more especially if not looked into in good time.

So what factors should you consider when thinking about what to fix in order to return your car’s performance to its former glory.

Dirty/clogged air filter

Car engines need air to operate optimally. Just as humans need air to live, engines need air to efficiently carry out the combustion process that releases kinetic energy hence moving the car. This is exactly the reason why cars would not run very well in areas at a very high attitude.

The air filter allows air to enter into the throttle body that determines how much air gets into the engine. If it is clogged the flow of air is disrupted hence the engine does not get enough oxygen. So check your air filter for dirt, or just switch it up and get a new one. An air filter would cost around Kes 1000 (USD 10) for most cars.

Loss of power from engine
Engine Air filter

Faulty spark plugs

Spark plugs provide are electrical conductor components that produce the sparks needed to begin the combustion process once the fuel and the air is compressed in the engine cylinders. If the spark plugs are faulty they would misfire leading to an inefficient/ insufficient power stroke due to less coordinated piston movements.

If the spark plugs are faulty the car engine will shake a bit rougher at idle (when the car gears are not engaged in drive for the automatic transmissions or when in neutral for the manual transmissions)

You should always have your spark plugs changed every 3rd service of the vehicle however in case you suspect the plugs to be the reason why the car is loosing power then just have them changed as soon as you can. A pair of normal plugs(Toyota) will cost you about Kes 2000 (USD 20) for a set of 4 however if you want to go for the better plugs get NGK iridium plugs which last longer and they will only cost about Kes 6000 (USD 60) for a set of 4.

engine loosing power
NGK Iridium Plugs

Clogged catalytic convertor

The catalytic convertor is a cleaning element that has been used in car exhausts since the 70’s. It breaks down the harmful toxic Carbon Monoxide ,Hydrocarbons and  Nitrous Oxides gases produced in the engine during combustion into Water, Oxygen, Carbon Dioxide and Nitrogen.

If a catalytic converter is damaged the car produces less power due to increased back pressure of the gases leaving during the cars exhaust stroke. The car may also produce excess carbon gases, which prompt the cars ECU (Cars computer brain) to make adjustments based on set parameters so as to produce less Carbon Dioxide. For this you may see a check engine light come up.

The most common sign that your Convertor has gone bad is a rattling sound that comes from the convertor chamber when you tap on it. Convertors are generally expensive and may run your pocket in the ranges of Kes 40,000 (USD 400) to buy new ones and fit into the car. Most people just remove them and drive along killing polar bears, causing global warming and affecting child birth all over the planet. It is not responsible to drive without a catalytic convertor. Most people argue that removing it enables you to make power gains in the car due to reduced back pressure but you can also buy high flow catalytic convertors that will still get the job done.

engine loosing power
Car catalytic converter

Clogged throttle control body

The throttle body regulates how much air gets into the engine based on how hard you press the accelerator. If the throttle body is sticky due to carbon deposits it may need a bit more energy to move. Hence you will notice that the car takes a second or two to gain the expected power when you put your foot down. Think of it as a tap. If the tap has a lot of salt deposits on it you require more energy to turn it right? Throttle bodies can easily be cleaned in a few minutes. All you need to buy is a Throttle body cleaner fluid, carburetor cleaners can also work fine. These usually cost around Kes 1500 (USD 15) at most the guy doing the job can charge and extra Kes 1500 (USD 15). Open the throttle body. Usually located at the base of the intake pipes where the pipe joins the engine. Spray the cleaner on the throttle body, use a clean rag to wipe out the throttle cleaner , let it dry and you will be good to go.

Note that some car manufacturers coat their throttle bodies with a special powder meant to assist normal operations of the throttle bodies hence you cannot use the Throttle cleaners on these cars. Check for a warning sticker on the throttle body itself before spraying  the throttle cleaner. This applies to some of the newer Ford vehicles mainly.

Engine loosing power
Cleaning Throttle Body – Image courtesy of the family Handyman

Faulty ignition coil packs

Ignition coils deliver the electrical connection to the spark plugs. These are the tubular elements that hold the spark plugs and stick our on the cylinder head. If they are faulty the spark plugs won’t get the require electricity to produce the sparks needed for combustion.Their wires could also be loose so have a look and check if all connections are ok.

You can test these out by removing them from the engine head and returning them ever so slightly touching the spark plug down there. listen for some sort of crackling electrical noise. If no noise is produced there could be a problem. You can also take the car in for diagnosis to find out. Coil pack are generally expensive costing anywhere from Kes 12,000 for a 4 cylinder engine to Kes 50,000 for a 4 cylinder engine for a much more rare car.

Note it is advisable to replace all coils at the same time, never replace them in isolation, as the other coils will  most likely follow suit in a few weeks.

engine loosing power
Ignition Coil – VW Specification

Faulty engine cooling system

If the car is not cooling effectively you will experience loss in power. Check your radiator and cooling tubes for any leaks. Also have your mechanic check out the thermostat that determines at what temperature to run the fans cooling the radiator. The best way to diagnose this is to check when your fans start running, if the fans are running even when the engine is cold then you may have a faulty thermostat. It will cost you anywhere between Kes 4500  (normal cars) – Kes 35,000 (premium cars) for a new thermostat. A new radiator will cost anywhere between Kes 5000 – Kes 30,000 for a second hand one.

engine loosing power
Engine thermostat housing

Worn wheel bearings

Worn wheel bearings may also cause some loss in power. The best way to diagnose this is listen for a turbo/supercharger kind of sound from your car while accelerating even though you don’t have a turbo or supercharger. The sound usually starts a few minutes after driving and will be persistent on longer journeys.

Engine loosing power
Wheel Bearings

Use of low quality fuel

If you use low quality fuel your engine may perform poorly mainly because of increased knocks. Sometimes the knocks may be really minute but they can set your engine off a coordinated rhythm. Try change up the fuel you use and check the difference. In Kenya Shell V-Power is the premium at the top, then Total’s Premium is second best then Shell’s Fuelsave comes third. Avoid filling the tank at fuel stations you do not trust since some of them may have fuel that is not regularly checked for quality.

Worn/slipping timing belt

if your timing belt is slipping it could cause you to loose power. This is easy to fix just get a new belt however ask the mechanic to also check the tensioners and pulleys for vibrations that may offset the belt later on.

engine loosing power
Timing belt

The aircon could be on

The aircon also utilizes some of the kinetic energy from the car. This you will notice a bit more when on an incline. So if you are looking to gain the most of your car for whatever reason…. maybe racing…In Kenya? Then you need to know the trade offs of the aircon system.

Faulty Turbo or supercharger

If your car utilizes forced induction technologies like Turbo’s or Superchargers and they become faulty you may experience great power loss. Have an experienced mechanic look at these components. It may be a faulty tube connector, dirt lodged in the turbo housing or the turbo could be poorly adjusted. Worst comes to worst you may need to buy a new or used turbo for between Kes 25,000  (USD 250) – Kes 150,000 (USD 1300) depending on the size some more premium turbos can go for an excess of Kes 500,000 (USD 5000) but no car in Kenya needs all that power now right?

Turbo Charger
Engine loosing power

Clogged Injectors

Just get some octane boosters to help you clean these out. A bottle or two every 5000kms on a full tank should clean out the system abit. Don’t expect too much. However using more quality fuel will ensure that the car’s injectors never get clogged.

Car loosing power
Fuel Injectors – image courtesy of dsgperformance

Vacuum Leaks

Vacuum leaks are air leaks within the engine system that cause inefficiencies within the engines performance range. In most cases they will cause the engine to consume more fuel. The car looses power and the engine produces a high pitched hissing sound if you listen carefully to it. The best way to diagnose and find a vacuum leak is to do the following.

  1. Let the engine cool off
  2. Get your cars fire extinguisher and keep it close
  3. Start the car
  4. Get the carburetor cleaning fluid or throttle body cleaner and spray it along the intake pipes, EGR valves, and the head of the engine where the gasket is situated.
  5. You will be looking for increased rough engine revving even though your foot is not anywhere near the accelerator pedal. At times the engine will just stall.
  6. Mark all areas that make the car behave as above when you spray the cleaner.
  7. Get those gaps fixed.

Here is an instructional video from Eric the car guy

Hope this helps you in understanding why your car may be loosing some performance. All in all we hope that you get your car tuned up for optimal fun.

If you think we forgot anything, feel free to leave a comment in the comment section below.



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