Certain engine failures, like a broken timing belt, are beyond any ECU’s control. However, MS3Pro can detect other failures and take action—either shutting down the engine to prevent damage or making adjustments to keep it running until the issue is resolved. These failsafes are available across the MS3Pro and MS3 series (V3.0, V3.57, PNP, Gen 1, Ultimate, EVO).
Note: Some features may require additional sensors, such as fuel or oil pressure
Key MS3Pro Engine Safeties:
- Rev Limiters: Set limits by cutting fuel, spark, or both
- Knock Sensing/Timing Correction: Automatically reduce timing in response to knock
- Coolant-Based Rev Limiter: Lower rev limits when the engine is cold or overheating
- Overboost Protection: Cuts spark or fuel if boost pressure exceeds safe levels
- Flex Fuel Sensor Out of Range: Adjusts fuel and timing based on sensor output
- AFR Safety: Shuts down the engine if AFR goes out of range
- Fuel Pressure Safety: Monitors fuel pressure and shuts down the engine if it drops too low
- EGT Safety: Adds fuel or shuts down the engine if exhaust temperature gets too high
- Oil Pressure Safety: Configures warnings or engine shutdown based on oil pressure
- Limp Home Modes: Activates backup sensor readings to protect the engine if a sensor fails
Rev Limiters
The MS3Pro’s basic failsafe is a rev limiter, which you can configure by cutting fuel, spark, or both. You can set a static rev limit or adjust it based on coolant temperature—allowing lower limits when the engine is cold or overheating.
Knock Detection
MS3Pro includes knock detection, reducing timing automatically if knock occurs. This feature can use one or two knock sensors to pinpoint affected cylinders and adjust timing either for specific cylinders or across the board.
Overboost Protection
MS3Pro prevents overboost damage by cutting fuel or spark when boost exceeds a set threshold. You can customize the boost threshold and select whether to cut fuel, spark, or both. For less severe overboosts, a gradual power reduction can be applied, while more critical levels trigger an immediate shutdown.
Fuel Failsafes
By connecting a fuel pressure sensor to the MS3, you unlock several protective features. Besides controlling a returnless fuel system, the MS3 can respond if fuel pressure deviates from expected levels.
MS3Pro Fuel Pressure Safety settings let you shut down the engine if fuel pressure drops under full throttle. You can also specify a delay before the shutdown occurs to filter out noisy signals. Additionally, MS3 can automatically correct for fuel pressure drops by adding more fuel.
The flex-fuel failsafe covers scenarios where the flex fuel sensor reports a frequency outside the acceptable range. You can set an assumed ethanol percentage and customize fuel and timing adjustments separately to avoid running too lean or advancing the timing too much.
Click here to read more about the MS3Pro’s Fuel Pressure Safeties
AFR Safeties
The AFR (air-fuel ratio) safety feature monitors for lean conditions. If AFR is out of range for a defined time, the system can shut down the ignition until the engine returns to safe operating conditions. This helps protect the engine from running dangerously lean.
Exhaust Gas Temperature (EGT) Safeties
MS3Pro allows you to configure EGT safeties, where high EGT readings trigger fuel adjustments or engine shutdown to prevent excessive exhaust gas temperatures, which could damage engine components.
Check Engine Light Functionality & Safety Actions
The MS3 includes check engine light functionality that monitors sensor readings, considering both voltage levels and fluctuations. Excessive fluctuation can indicate noise, while minimal fluctuation may suggest a disconnected sensor.
The MS3 can respond to sensor failures by substituting fixed values—like using a time-based value for a failed coolant temperature sensor that simulates a warm-up cycle. The MS3 can also estimate MAP sensor readings based on RPM and throttle position if the MAP sensor fails.
At the same time, you can use an alternate maximum boost level and rev limit to avoid going all-out on broken sensors.
Oil Pressure Failsafes
The MS3Pro can monitor oil pressure, allowing you to set safe limits based on RPM. If pressure falls outside this range, you can trigger a warning light, activate limp mode, or shut down the engine.
