M44 TLEV Engine

M44 TLEV ENGINE



All M44 engines produced from 1/97 forward are being upgraded to a Transitional Low Emission Vehicle (TLEV) for Federal emission control standard compliance.

The TLEV requirements are similar to the system functions of the MS 41.1 TLEV compliant system introduced with the E36 - 328i for 1996. The M44 continues to comply with OBD II standards for emission control monitoring and continues to use the M5.2 engine management control system manufactured by Bosch.

Additions to the M44 engine for TLEV compliance include:
- Secondary air injection system
- Purge system monitoring
- Fuel System Running Losses control solenoid

The balance of the Engine management system for OBD II compliance remains the same. Please refer to the M44 Engine Introduction and M44 Update section of the M62 engine Introduction handouts for information on the M44 - M5.2 engine management system.

Additionally, the M44 EZA traction control system is being updated to an ADS throttle control system with an updated control module.

SECONDARY AIR INJECTION
Secondary air injection has been added to the M44 engine to enable it to comply with TLEV standards. It is an output control function of the M5.2 engine control system. The operation of the Air Injection system is similar to the MS 41.1 system used on the 2.8 liter engine.

The system consists of the following components:



- Secondary Air Injection Electric Motor/Pump
- Motor Pump Relay



- Vacuum Vent Valve (solenoid)



- Non-Return Valve
- Secondary Air Injection Pipes

SECONDARY AIR INJECTION CONTROL



The parameters for air injection operation are as follows:
- Below -10 °C, the injection pump is activated briefly to blow out any accumulated moisture and prevent it from freezing.
- Between -10 °C and 40 °C, the air injection pump is switched on, on start up, for of 2 minutes.

SECONDARY AIR INJECTION MONITORING
Component operation of the air injection pump and vacuum vent valve are monitored by the M5.2 control module. The system checks the operation of the system by monitoring the final stage control in the control module.

PURGE SYSTEM CONTROL



The purge control system on the M44 engine has been modified to allow it to comply with TLEV standards. Purge control and monitoring are control functions of the M5.2 management system.

The system is redesigned and matches the purge control system found on the E36 - 328i. The components of the M44 purge system include:
- Charcoal canister with integrated shut off valve
- Evaporative purge valve
- Fuel tank pressure sensor
- Liquid vapor separator
- Vehicle fuel tank
- M5.2 control module



The charcoal canister is 3.0 liters in size and its installed location is in the trunk, under the spare tire. The larger canister allows for the containment of more HC vapors with less escape to the atmosphere. Vapors that accumulate in the canister are allowed to pass through the liquid/vapor separator and condense back into the fuel tank.