Car/Truck Sensors - Sampling Rate?

[Fran3]

Probably varies depending on which sensor and what conditions... but not sure.

Can anyone give me some idea of how often a car/truck ECU/ECM samples various vehicle sensors.

1. Mass Airflow Sensor
2. Knock Sensor
3. Manifold Absolute Pressure Sensor
4. Oxygen/O2 Sensor
5. NOx Sensor
6. Engine Speed Sensor
7. Throttle Position Sensor
8. Crankshaft Position Sensor
9. etc

For example:
At 6,000 RPM... that's 100 Rotations Per Second.

So if we sampled a sensor once per Rotation that would be 100 Samples Per Second
And if the ECU/ECM is monitoring 50 sensors at that rate...
then it would be taking samples 5,000 Per Second.

Or if we sampled the sensor 10 times per Rotation that would be 1,000 Samples Per Second.
And if the ECU/ECM is monitoring 50 sensors at that rate...
then it would be taking 50,000 Samples Per Second.

But of course the sample rate may vary for various sensors... but I'm not sure...
So thanks for any help on researching the typical sample rate for various vehicle sensors.

 

[ZipZapOuch]

The crank shaft position sensor (or cam shaft position sensor) is monitoring constantly and, in some cases, knock is calculated from the shaft's angular velocity or, more accurately, the deceleration of the shaft associated with knocking. I think the shaft is monitored every degree of every rotation. So, at 6000 rpm, that's a lot of data points but, each pulse of each injector is also controlled by the ECU.

 

[Tony Stewart]

Chat GPT4 says this;

1. Mass Airflow Sensor (MAF): The MAF sensor is crucial for determining how much fuel needs to be injected into the engine. It is typically sampled at a high rate to accurately match air intake with fuel injection. Sampling rates can range from 100 Hz (100 times per second) to up to 1 kHz (1000 times per second), depending on the system's requirements.

2. Knock Sensor: This sensor detects engine knock or pinging, which is indicative of premature combustion. It needs to sample at high frequencies because it's monitoring vibrations. Sampling rates can be in the range of 6 kHz to 15 kHz.

3. Manifold Absolute Pressure Sensor (MAP): The MAP sensor provides instant manifold pressure information to the ECU, which is crucial for calculating the air density and determining the engine's air mass flow rate. It's usually sampled at a rate similar to the MAF sensor, around 100 Hz to 1 kHz.

4. Oxygen/O2 Sensor: The O2 sensor measures the oxygen level in the exhaust gases, allowing the ECU to adjust the air-fuel mixture for optimal performance. These sensors are typically sampled at a rate of around 1 Hz to 10 Hz, as the exhaust gas composition doesn't change as rapidly as other parameters.

5. NOx Sensor: NOx sensors monitor the level of nitrogen oxide in the vehicle's exhaust to control emissions. Like the O2 sensor, they don't require extremely high sampling rates, and you might see rates in the range of 1 Hz to 10 Hz.

6. Engine Speed Sensor: This sensor measures how fast the engine is running (RPMs). Since engine speed is critical for various calculations (such as ignition timing), it is sampled frequently, typically in the range of 100 Hz to 500 Hz.

7. Throttle Position Sensor: This sensor tells the ECU how far the throttle is open, which helps determine how much air is entering the engine. Its sampling rate can vary, but it's usually in the range of 100 Hz to 500 Hz, allowing the ECU to make quick adjustments.

8. Crankshaft Position Sensor: This sensor is vital for engine timing – it tells the ECU the position of the crankshaft. This allows the ECU to time the spark plugs and fuel injectors accurately. It needs to be sampled at a very high rate, often in the range of 1 kHz to 10 kHz, because of the high speed of engine rotation.

These are general guidelines, and the actual sampling rates can vary based on the vehicle's make, model, and specific engine characteristics. Do you have a specific vehicle or application in mind? That might help narrow down the answer further.
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