Your car has a lot of sensors that control various parts of your car and monitor its performance. If the sensors in your engine aren’t functioning, your car will be less and less reliable and you will be more likely to be stranded in a broken-down car. Many are extremely important in keeping your car running, like the crankshaft position sensor.
Today, we are explaining the importance of the crankshaft sensor in your vehicle, what you might experience if it is failing, and what you can do if you believe it is the blame for your engine troubles.
What is a Crankshaft Position Sensor?
A crankshaft position sensor is an electronic device on both petrol and diesel engines to monitor the position or speed of the crankshaft. They also help with ignition timing and Engine RPM levels.
The data created from the sensor goes to the engine’s ECM to time: fuel injectors, ignition systems, and other engine settings.
The camshaft position sensor tells you when a cylinder is firing to help time the fuel injector and coil firing.
If the these sensors were to stop working properly, it would not be able to start the engine at all. Usually, it is able to be put inside the transmission housing or in the cylinder block of the engine. In other vehicles, the sensor is very close to the main pulley for the engine and the cam sensor.
This is one of the more critical sensors in the modern-day engine along with the cam sensor.
The crankshaft position sensor signal is a typical start for fuel injection or spark ignition. If it fails, you would have operational issues either not starting or allowing the engine to die while in motion.
Functions of Crankshaft Position Sensor
The crankshaft sensor is positioned so that the teeth of the reluctor ring are near the sensor tip and attached to the crankshaft. There are one or more teeth missing from the reluctor ring so that the ECM has a reference point for the position of the crankshaft.
As the crankshaft turns, the sensor creates a pulsed voltage signal that corresponds to each pulse and is relative to a tooth on the reflector ring. Typically, the hesitant ring is created by way of missing teeth.
The ECM uses signals from the crankshaft position sensor to determine when to generate a spark, as well as which cylinder to send it to. In addition, the signal is also used to determine if a cylinder is misfiring. In a diesel engine, the sensor operates the fuel injection system.
The sensor output can be correlated to other sensor data, including cam position, to determine the current combustion cycle, this is very important for a four-stroke engine. If the sensor is damaged, there is no spark and the fuel injectors will not work.
Crankshaft Position Sensor Location
The crankshaft position sensor may be in a different location based on the engine design and type of vehicle. Obviously, it is located closer to the crankshaft. It is typically mounted on the front of the engine on the timing cover.
It can be also mounted on the engine’s rear or side in some models. In some models, the sensor measures the speed from the clutch flywheel to determine the speed of the crankshaft. If so, the sensor is attached to the bell housing of the transmission.
Types of Crankshaft Position Sensor
There are four types of crankshaft position sensors::
- Inductive sensor
- Half effect sensor
- Optical sensor
- Special type
#1. Inductive Sensor.
The sensor consists of a magnetic core and copper wire coil that’s wound around an isolated shaped coil, and it generates an AC voltage signal. Locations are either in the engine block, near the flywheel, or near the crankshaft.
It reads notches on a spinning disk, reluctor wheel, or crankshaft. When the notch passes through the sensor, it generates a change in the magnetic field that causes an alternating current signal to be sent to the ECM.
#2. Half Effect Sensor.
Hall-effect sensors produce a digital square wave signal, not an analog AC signal. They have one connector with three pins (reference voltage, ground, and signal). The advantage of Hall effect sensors is they can sense static (non-variable) magnetic fields.
Hall-effect sensors are mounted in the same locations as the inductive sensor, and respond to the same notch, on or off, as the notch moves past the sensor. These types of sensors are very popular in modern types of cars.
#3. Optical Sensor.
Optical sensors are, however, not very resistant to fouling, but do have the ability to detect edges with extreme precision.
#4. Special Type of Crankshaft Position Sensor.
Some engines, like those in the GM Premium V line, utilize a sensing ring mounted to the harmonic balancer to read the crank position sensor.
This provides a much better means to ascertain the position of the crankshaft (and all connected components) across the entire run of the engine, as well as provide the computers with the crankshaft’s precise position within a few degrees.
Symptoms of Crankshaft Position Sensor
Crankshaft speed and position are two important parameters in every engine, and they play a significant role in the calculations for engine management. Many engines will not start without accurate data from the crankshaft position sender.
There are several possible symptoms of a faulty crankshaft sensor that will usually alert the driver of an important issue that needs to be attended to. Some of the more major symptoms are as follows.
- Check engine light ON
- Engine misfires
- Vibrations in engine
- Poor engine performance
- Difficulties in engine starting
- Engine stalling
- Rough idling
- Poor gas mileage
- Acceleration problems
- Extended cranking
#1. Check Engine Light ON.
This is the most common symptom and happens almost every time there is wear on the crankshaft position sensor.
The check engine light will come on when the computer is alerted to the problem and is notified of a possible signal issue with the crankshaft position sensor.
The positive is that the check engine light was designed to help protect the engine from damage. The downside to this issue is that these symptoms will affect performance. The more you leave the problem unattended, the more it is likely to worsen.
#2. Engine Misfires.
This is the most common symptom and happens almost every time there is wear on the crankshaft position sensor.
The check engine light will come on when the computer is alerted to the problem and is notified of a possible signal issue with the crankshaft position sensor.
The positive is that the check engine light was designed to help protect the engine from damage. The downside to this issue is that these symptoms will affect performance. The more you leave the problem unattended, the more it is likely to worsen.
#3. Vibrations in Engine.
A malfunctioning crankshaft position sensor fails to optimize performance. With a malfunctioning sensor, there is no monitoring of crankshaft status, which leads to severe engine vibrations.
It may even utilize wrong readings to determine fuel and ignition timing. When the ECM is malfunctioning, expect an uneven ride.
After holding the steering wheel, you can feel these vibrations in the steering. This problem will only worsen until it is rectified.
#4. Poor Engine Performance.
A bad crankshaft position sensor will also lower your engine performance. If your vehicle has a malfunctioning crankshaft position sensor, the engine control unit will not know the correct position of the crankshaft or cylinder.
This delay will affect the engine control unit’s ability to control engine operation and performance, making the gas pedal feel sluggish. There are times where it does not even engage at all. This can be a hazard while driving in a situation where you need to accelerate fast without stopping.
#5. Difficulties in Engine Starting.
If your crankshaft position sensor cannot sync at all it means it is completely bad, you could have trouble starting your vehicle.
What typically happens is, when the crankshaft position sensor is having a problem, it will sometimes receive a malfunction code indicating, there is some type of a problem with its functionality.
As a result of this, the ECM does not know when to fire the spark plug and pulse the fuel injector, so your engine could potentially be void of either fuel or spark which will cause the vehicle to not start. If this negative condition continues, or persists, you may experience a complete engine failure and therefore not be able to start your engine.
#6. Engine Stalling.
If there is an issue with the crankshaft position sensor or its wiring, it can cut off the crankshaft signal while the engine is running, resulting in engine stalling.
Engine stalling is a direct indication of a wiring issue in the sensor. However, engine stalling may also be caused by a decrease in fuel pressure or a decrease in airflow.
Fuel injection calculations require a functioning crankshaft position sensor to continuously send accurate data to the ECM. When the crankshaft position sensor fails, the data from it is not getting to the ECM, and that creates a stalling condition.
#7. Rough Idling.
Rough engine idling can also be caused by a bad crankshaft sensor.
Rough idling means the ECM is not getting data from the defective crankshaft position sensor, which means it is firing the fuel injector or spark plug at incorrect times, and therefore not monitoring the crankshaft position properly. The result is an engine that causes vibration that affects overall engine power.
There are a variety of reasons for rough idling, so it may be difficult to point out the exact cause. So if the engine is vibrating in an idle, have your CPS performed.
#8. Poor Gas Mileages.
For your engine to run correctly while still getting good fuel mileage, the crankshaft sensor needs to be functioning properly. If the CPS is faulty, it won’t provide accurate timing information, and the injectors may not be cycling the fuel properly into the engine.
Your engine will then be running with an improper fuel mixture and it will consume an unnatural amount of fuel, worsening the problem. This will cause multiple drivability issues with poor mileage, and could also harm your engine.
Because of this, you need to have that sensor checked out by a mechanic very soon, and your fuel mileage could very well be a result of another failure.
#9. Acceleration Problems.
If the crankshaft position sensor sends a false reading, then your engine is going to struggle to remain in sync with acceleration speed.
The drop is expected because the engine can’t detect how quickly the crankshaft is rotating to proportionately increase fuel and modify the ignition timing.
As CPS wears out, the engine control unit cannot modify spark timing and fuel injection as engine rpms increase. Inaccuracy while accelerating can lead to uneven acceleration and it can also be difficult to maintain a constant speed.
#10. Extended Cranking.
Since the ignition is off with the timing sensor, you will have trouble starting your vehicle.
You may experience extended crank times before your vehicle is actually running, but a faulty crankshaft position sensor could also cause a crank and no start.
A faulty crankshaft position sensor will lead to an increase in your vehicle starting time. It may only occur on occasion, but you should pay attention and not ignore this as it could cause internal damage to the engine.
Crankshaft Position Sensor Replacement
If the crankshaft sensor goes bad, your engine may run poorly or not at all. Replacing the crankshaft position sensor is easy but does require some specific steps to be taken. Most of these steps are the same on all engines.
- To replace the crankshaft sensor by yourself you’ll need some materials and tools including a floor jack, jack stand, ratchet & socket set, cleaner, and a new crankshaft sensor.
- To begin, jack your vehicle up using jacks and jack stands to ensure your vehicle is secure and prepared.
- Next, after you are finished with the preparation, you need to unplug the sensor’s electrical connector from the engine wiring harness.
- Then, find the location of the sensor mounted near the crankshaft pulley. Once the location is determined, find the proper size socket and ratchet handle to remove the sensor bolt.
- Next, lubricate the O-ring on the new sensor (this makes it easier to install).
- Next, twist the new crankshaft position sensor onto its mounting surface and reinstall the bolts.
- At this point plug the new crankshaft position sensor into the engine wiring harness. Using a clip to secure the sensor so it won’t unplug while in operation is also recommended.
- Finally, lower the vehicle and remove the jack stand.
Advantages of Crankshaft Position Sensor
Here are a few of the notable benefits of CrankshaftPositionSensor:
- Timing of fuel injection and ignition is more accurate meaning engines performance will be better.
- Increased fuel efficiency as the engine is synchronised better.
- Reduction in harmful emissions due to better controlling of the combustion of the engine.
- Control of engine misfire which makes engine run smoother.
- Real-time monitoring of an engine’s issues and diagnosis capability.
- Enables smoother start and idle by sending crucial data to the engine.
- Improved engine experience and overall pleasant driving by ensuring power is delivered consistently.
Disadvantages of Crankshaft Position Sensor
Some of the disadvantages include:
- They can be damaged or have a fault in the electronics resulting in engine performance issues.
- Since the crankshaft position sensor is electronic it is vulnerable to electrical failure and/or faults in the circuitry.
- Increased complexity can lead to specialized engine diagnostics to pinpoint problems.
- Repairs can be expensive if your crankshaft position sensor needs replaced as it is likely to be ‘hard-wired’ into your engines operational systems.
- It often gets contaminated by oil and debris making it fail all together.
- Since your engine relies on accurate readings from your crankshaft position sensor it is a good idea to understand the health of your crankshaft position sensor.
Final Thought
Crankshaft sensors are commonly used to record critical data, such as engine speed (RPM), piston position for ignition timing adjustments, and whether or not a misfire has occurred. Also, if a crank sensor is broken, it can fail.
If a crankshaft sensor is not replaced in time, the chance for engine damage increases. Worst-case scenario, the engine could completely fail. Call a very experienced mechanic to change the crankshaft sensor immediately or you can do it yourself.