Why is Your Car Engine cannot Rev up and has Low Power

Most of the the new model vehicles now are equipped with many accessories, aimed at improving the power output, fuel economy and reducing emissions. 

By the time these parts/accessories begin having faults due to wears or accumulation of dirt, the vehicle will start to malfunction. There're many reasons for a problem of acceleration for many vehicles but few cases are discussed below

If your car's engine not rev up more than 3000 rpm when you pressed throttle pedal down completely, check the following parts of the engine:

Catalyst

A catalytic converter is a car's component that's used for emission and polluton control. It's a metal canister installed in the exhaust system. It's filled with chemical catalyst, usually a platinum and palladium mixture, and helps to convert  the vehicle's emissions into non harmful gases.

 The blockage of the catalyst will cause the engine hard breathing and consequently, will have revving issues, as exhaust gas will not move freely out of the tailpipe.  

Most noticeable symptoms of a bad/restricted exhaust catalyst 

• Hard starting 
• Excessive heating of inner part of the vehicle 
• Engine hesitation, especially when cold to accelerate 
• Engine overheating 

Restricted exhaust catalyst is very fatal to an engine if the fault is not arest in time.

Fuel pump/Air flow Meter

For normal combustion to take place, there must be enough:

1. air
2. fuel
3. spark

A reduction in any of these three components will result to abnormal work of the engine.

 If the pumping pressure of the fuel pump is low,  it'll be hard for engine to rev up, it'll even shut the engine, when you dwell too much on the throttle pedal while trying to rev the engine up.

It's a good practice when replacing the fuel pump of an engine to replace the fuel filter also. 

When an air flow meter is dirty, the picture below

A dirty MAF sensor 

a car will have difficulty revving up, you'll constantly loose power on acceleration. 

This problem is easily solved by cleaning the MAF sensor and replacing the engine air filter. 

Camshaft position sensor and Crankshaft position sensor

These two sensors control the valve timing and the ignition timing respectively.

They detect when the valves are opened by the rotation of the camshafts and crankshaft, then send the signal to brain box (ECU) of the engine to supply the needed  amount of fuel and the spark for effective combustion.

When the two readings of these sensors are not correlated, the engine will malfunction, sometimes your engine will not be able to rev up above 3000 rpm, depending on how severe is the condition. This case will trigger data trouble codes  P0016 and P0018 on toyota vehicles. 

A damaged timing plate or the timing teeth of the crankshaft can also cause the vehicle  not to rev above 3000 rpm. 

There was a time  I replaced the  crankshaft of one 2013 Hyundai Elantra. after starting the engine, they was a check engine light, which I had to scan to know the reason.  It was  P0335 which was so severe that I couldn't rev the engine above 3000 rpm. I inspected everything, tried to change the  crankshaft sensor, inpected the wires, all to no avail until I loose back the engine. it was then I detected that the sprocket attached to the crankshaft  was pressed. I replaced it with the one on the old crankshaft, that's  how I solved the problem.  

Paying attention to every parts of the engine is very necessary when you're rebuilding an engine to avoid double work and waste of energy trying to figure what's the cause of the problem, due to your negligence.

On this same Hyundai engine, the crankshaft sensor wire has the same design as its knocking sensor, care should be taken not to exchange them, as the engine will not be able to start, and even if it starts,  will not rev up.

Having OBDII scanner, even if it's a cheap one will greatly help you to pin point the likely areas of the fault on your engine.  Get one here

Incorrect timing

If you've recently worked on the engine that involved altering the valve timing or the ignition timing, just check it. normal timing of an engine is between 10 -0 degrees before TDC. The maximum is at 0 degrees. Just check to confirm that the timing marks of the camshafts must also align correctly as the  misalignment  will cause the engine to loose its revving power.

symptoms of incorrect timing are:

• shooting
• hard starting
• hard acceleration
• difficulty to climb hills
• engine vibration on idling
• check engine light

dirty or bad injector nozzles

When you usually allows fuel to dry completely  from the tank, injectors will draw up dirts that'll block their holes. when this happens engine will not rev  fine, at times it'll idle rough. 

when your nozzles are dirty, clean them with with injector cleaner.

 

They're other things that may cause an engine not to rev up above 3000 rpm, kindly commment below if you have any contribution, or facing this kind of problem in your car.

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