What Is A Camshaft?
A camshaft is a rotating component, a simple rod or shaft, usually made of metal, containing ‘cam lobes’ that convert rotary motion into reciprocating motion. When the shaft is rotated, the cam allows it to act on a valve or switch to an appropriate degree of its shape, and the speed of rotation controlling the rate of action.
Camshafts are used in internal combustion engines to operate the intake and exhaust valves and in mechanically controlled ignition systems and early electric motors as speed controllers.
In a modern internal combustion engine, they are typically, but not necessarily, positioned directly above the cylinder banks where they control the valves. Their calibration precisely controls the amount of air-fuel mixture entering the chamber and how efficiently the spent exhaust gases from the previous ignition can exit the chamber to make room for the next charge.
Not only does this make them critical to the operation of an engine, but because the opening and closing of the valves must be carefully and perfectly synchronized with the piston movements, they also have a drastic effect on performance.
To ensure this timing, the camshafts are connected to the rotation of the crankshaft via a Timing belt or chain, which moves the pistons in the cylinder directly. In addition, the shape of the cams themselves has been carefully designed to control the speed at which the valves open and close. This is better known as variable valve timing.
The camshaft was described in 1206 by the Arab engineer Al-Jazari. He used it as part of his automata, water raising machines and water clocks like the castle clock.
The first cars to use single overhead cam engines included the Maudslay designed by Alexander Craig and introduced in 1902 and the Marr Auto Car designed by Michigan’s Walter Lorenzo Marr in 1903.
How does a camshaft work?
A camshaft is a rod that rotates and slides against a machine to convert rotary motion into linear motion. This change of motion is achieved by the camshaft moving further and closer from from the axis of rotation while the machine pushed the camshaft.
A camshaft on an internal combustion heat engine is a device that controls both the input of fuel and the expulsion of exhaust fumes. It consists of several radial cams, each displacing intake or exhaust valves. This camshaft is connected to the crankshaft via belt, chain, or gears. This ensures consistent timing of the valves in relation to the motion of the pistons.
The camshaft is driven around by a toothed gear, which receives drive through the timing belt or chain from the crankshaft. The four-stroke engine cycle requires two rotations of the crankshaft for a complete cycle, and so the camshaft is driven at half the speed of the crankshaft.
Now, you know the importance of camshaft, but how can we find it working correctly or not? For this purpose, many modern engines come with a camshaft position sensor.
What is A Camshaft position sensor?
Camshaft position sensors monitor the camshaft’s position and send information to the engine control unit about when each valve is open on a particular cylinder. They work closely with crankshaft position sensors to paint a complete picture for the engine control unit.
The engine control unit needs this data to control how much fuel enters the combustion chamber and ignition timing (spark timing) to ignite the fuel, when the air-fuel mixture is ignited simultaneously, engine performance increases, fuel consumption, and tailpipe emissions decrease.
In modern auto-start / auto-stop engines, the camshaft position sensor determines which cylinder is on its power stroke relative to the crankshaft position and provides fuel and spark to start the engine when you step on the accelerator pedal.
A defective camshaft position sensor can warn you before it fails and leaves you stuck.
Symptoms of a Bad Camshaft Position Sensor
1. Check Engine Light Comes On
The first thing you should notice if your camshaft position sensor is defective or having problems is that your “Check Engine” light in your dashboard will come on. Obviously, the “Check Engine” light can indicate various problems and not necessarily a defective camshaft sensor.
In this case, you should either use an OBD II (on-board diagnostics II) system to monitor vehicle hardware and software efficiently. You can detect part deterioration that causes imperceptible performance changes before a part completely fails.
Ignoring the Check Engine light can lead to expensive engine or transmission repairs.
2. Ignition Problems
When a camshaft position sensor gets into trouble and weakens, the signal, it sends to the car’s computer also weakens. This means that the signal will eventually be so weak that the car will not start because there is no spark from the ignition.
3. Car Jerking or Surging
If you are driving your vehicle and the camshaft position sensor starts failing, the engine will at times lose power and cause your car to jerk or randomly surge forward.
These result from an improper amount of fuel being injected into the cylinders since the PCM is getting incorrect information from the camshaft position sensor.
4. Poor Drivability
A failing camshaft position sensor begins losing its ability to transfer data quickly. Mismatched fuel delivery and ignition timing, even if off by a few milliseconds, will cause your vehicle to sputter, accelerate poorly, lack power, stall, or even shut off.
5. Transmission Shifting Problems
Certain cars with a bad camshaft position sensor will end up with a locked transmission that stays stuck in a single gear. The only way you’ll be able to get out of that gear is to shut off your engine, wait a bit, and then restart.
This is only a temporary solution, and the problem will reappear, so replacement of the sensor is necessary as a permanent fix.
Along with this, a failing camshaft position sensor can keep transmission shift solenoids from operating and gears from shifting. Called “limp-home-mode,” some models help protect the engine from damage by restricting engine speed.
6. Bad Fuel Economy
Inaccurate camshaft position sensor data can keep fuel injectors open too long, forcing excess fuel into the combustion chamber. This also can cause engine knocking and serious damage if too much liquid gasoline (which does not compress) builds up in the combustion chamber.
7. Engine Stalling
An even worse scenario than not starting your car is that your engine actually shuts down or stalls while driving because the fuel injectors are not instructed to inject fuel into the engine cylinders.
Camshaft Position Sensor Replacement Cost
We probably don’t need to tell you how dangerous this situation could be.
To replace a camshaft position sensor, you can expect between $ 95 and $ 200. The parts alone cost between $ 25 and $ 100. The labor cost for a professional replacement will range from $ 70 to $ 100.
Expect to pay more if you own a luxury vehicle or have the exchange done by your local car dealer. Additional fees and taxes are added to these costs.
Can You Replace a Camshaft Position Sensor Yourself?
Yes. This is one of those jobs that almost anyone can do and is an easy way to save yourself the minimum labor fee (often close to $ 100) that a repair shop or dealer will charge you. It should take around 5-10 minutes to replace it.
How to Replace a Camshaft Position Sensor
- Disconnect the negative battery cable.
- Locate the sensor. It’s usually on the top, front, or rear part of the engine. It will likely have a 2-3 wire connector attached.
- Release the tab on the sensor to disconnect the wires from the sensor.
- Remove the mounting bolt which attaches the sensor to the engine. It’s usually an 8mm or 10mm bolt.
- Pull the sensor off with a slight twist.
- Apply a bit of engine oil to the o-ring of the new senor.
- Install the new camshaft position sensor and secure it with the mounting bolt.
- Reconnect the wire connector to the sensor.
- Reconnect the negative battery terminal.