ECM Control BMW Z4 E85/E86

ECM Control

Electric thermostat activation is based on the following parameters

1. Engine temperature > 113°C
2. Radiator Coolant Outlet Temperature
3. Load signal "ti" > 5.8 ms
4. Intake air temp > 52°C
5. Vehicle speed > 110 MPH

When one or more of these monitored conditions is determined, the ECM activates (switched ground) the thermostat circuit. The activated heating element causes the wax core in the thermostat to heat up and open the thermostat increasing coolant circulation through the radiator which brings the engine temperature down.

The temperature of the coolant at the inlet side of the water pump will drop to approximately 85°C and the temperature at the outlet side will drop to approximately 103°C when activated.

Scheme 462

The "Malfunction Indicator Light" (MIL) will be illuminated under the following conditions

1. Upon the completion of the next consecutive driving cycle where the previously faulted system is monitored again and the emissions relevant fault is again present.
2. Immediately if a "Catalyst Damaging" fault occurs (see «MISFIRE DETECTION»(/bmw/z4/e85e86-2002-2005/remont/testing-diagnostics/#engine-management-overview__misfire-detection) ).

Scheme 463

The illumination of the light is performed in accordance with the Federal Test Procedure (FTP) which requires the lamp to be illuminated when

1. A malfunction of a component that can affect the emission performance of the vehicle occurs and causes emissions to exceed 1.5 times the standards required by the (FTP).
2. Manufacturer-defined specifications are exceeded.
3. An implausible input signal is generated.
4. Catalyst deterioration causes HC-emissions to exceed a limit equivalent to 1.5 times the standard (FTP).
5. Misfire faults occur.
6. A leak is detected in the evaporative system, or "purging" is defective.
7. ECM fails to enter closed-loop oxygen sensor control operation within a specified time interval.
8. Engine control or automatic transmission control enters a "limp home" operating mode.
9. Ignition is on (KL 15) position before cranking = Bulb Check Function .

Within the BMW system the illumination of the Malfunction Indicator Light is performed in accordance with the regulations set forth in CARB mail-out 1968.1 and as demonstrated via the Federal Test Procedure (FTP). The following page provides several examples of when and how the Malfunction Indicator Light is illuminated based on the "customer drive cycle".

Scheme 464

1. A fault code is stored within the ECM upon the first occurrence of a fault in the system being checked.
2. The "Malfunction Indicator Light" will not be illuminated until the completion of the second consecutive "customer driving cycle" where the previously faulted system is again monitored and a fault is still present or a catalyst damaging fault has occurred.
3. If the second drive cycle was not complete and the specific function was not checked as shown in the example, the ECM counts the third drive cycle as the "next consecutive" drive cycle. The "Malfunction Indicator Light" is illuminated if the function is checked and the fault is still present.
4. If there is an intermittent fault present and does not cause a fault to be set through multiple drive cycles, two complete consecutive drive cycles with the fault present are required for the "Malfunction Indicator Light" to be illuminated.
5. Once the "Malfunction Indicator Light" is illuminated it will remain illuminated unless the specific function has been checked without fault through three complete consecutive drive cycles.
6. The fault code will also be cleared from memory automatically if the specific function is checked through 40 consecutive drive cycles without the fault being detected or with the use of either the DISplus, GT1 or Scan tool.

Note. In order to clear a catalyst damaging fault (see MISFIRE DETECTION ) from memory, the condition must be evaluated for 80 consecutive cycles without the fault reoccurring.

Before any service work is performed on any fuel system related component, always adhere to the following

1. Observe relevant safety legislation pertaining to your area.
2. Ensure adequate ventilation.
3. Use exhaust extraction system where applicable (alleviate fumes).
4. DO NOT SMOKE while performing fuel system repairs.
5. Always wear adequate protection clothing including eye protection
6. Use caution when working around a HOT engine compartment
7. BMW does not recommend any UNAUTHORIZED MODIFICATIONS to the fuel system. The fuel systems are designed to comply with strict Federal Safety and Emissions Regulations. In the concern of product liability, it is unauthorized to sell or perform modifications to customer vehicles, particularly in safety areas.

The "Malfunction Indicator Light" can be diagnosed with an aftermarket Scan Tool that allows Technicians without BMW Special Tools or Equipment to Diagnose an emission system failure. With the use of a universal scan tool, connected to the "OBD" DLC (located in the driver's side left lower instrument panel area) an SAE standardized DTC can be obtained, along with the condition associated with the illumination of the "Malfunction Indicator Light". Using the DISplus or GT1, a fault code and the conditions associated with its setting can be obtained prior to the illumination of the "Malfunction Indicator Light".

Scheme 465

Testing the Oxygen Sensor should be performed using the DISplus Oscilloscope from the "Preset Measurement" List. The scope pattern should appear as below for a normal operating sensor.

If the signal remains high (rich condition) the following should be checked

1. Fuel Injectors
2. Fuel Pressure
3. Ignition System
4. Input Sensors that influence air/fuel mixture
5. Engine Mechanical

If the signal remains low (lean condition) the following should be checked

1. Air/Vacuum leak
2. Fuel Pressure
3. Input Sensor that influence air/fuel mixture
4. Engine Mechanical

Note. A MIXTURE RELATED FAULT CODE SHOULD BE INVESTIGATED FIRST AND DOES NOT ALWAYS INDICATE A DEFECTIVE OXYGEN SENSOR!