The year, make, model and engine info would help.
For an NPR the rpm sensor is located left rear of engine by the frame rail. Its actually the engine speed per service manual but when you need to replace the sensor the parts department calls it the rpm sensor. Good luck.
crank sensor
There is a grey 4 pin plug on top of the motor, close to the firewall, it controls the RPM, Speedometer, and Temperature gauges. Plug may become loose, causing no RPM needle movement.
The rpm is acquired on almost all computer controlled vehicles from the crank sensor. drl
A 2003 Mercury 115 that runs rough at a low rpm might be having a problem with the MAP Sensor or the Oxygen Sensor. The MAP Sensor is going to be the easiest one to replace because it is usually located plugged into the EFI (Electronic Fuel Injector), a fancy would for carburetor.
Here's a link that may help. The RPM sensor is also known as a crank position sensor. http://www.volvoclub.org.uk/faq/EngineSensors.html#Crank_Postition_Sensor
The RPM sensor and speed sensor serve different purposes, though they can sometimes be related. The RPM sensor measures the rotational speed of an engine or component, typically expressed in revolutions per minute (RPM). In contrast, a speed sensor measures the vehicle's speed, often in miles per hour or kilometers per hour. While both sensors provide vital information for vehicle performance, they are distinct in their specific functions.
To install an RPM sensor on a 60 Series Detroit engine, first, ensure the engine is turned off and disconnect the battery. Locate the existing RPM sensor, usually found near the flywheel housing or crankshaft. Remove the old sensor and clean the mounting area, then install the new RPM sensor in the same position, ensuring it is properly aligned and secured. Finally, reconnect the battery and check the sensor's functionality.
it is located at the side of the rotary injection pump
On a 2001 Audi TT, the RPM sensor, also known as the crankshaft position sensor, is typically located near the engine's crankshaft. It is mounted on the engine block, often near the transmission bell housing. To access it, you may need to remove some components for better visibility. Always consult the vehicle's service manual for specific details and diagrams.
The RPM gauge sensor on a 1992 Dodge Stealth RT Twin Turbo is typically located near the engine's crankshaft. Specifically, it is often found on the transmission bell housing or near the ignition coil area. This sensor picks up the engine's rotational speed to provide information to the gauge on the dashboard. For precise location and access, consulting the vehicle's service manual is recommended.
Possibly a MAP sensor issue. the MAP sensor limits RPM's to 2k. If that sounds like the problem, look at the vacuum hoses to the sensor. MAP sensor is located on the left strut tower looking at the engine.