Fuel Injection (CIS-E)
Fig. 59 CIS-E I/O Diagram:
55 Pin CIS-E Control Unit Terminal Designations:
The CIS-E system precisely controls fuel injection quantity under varying operating conditions. The CIS-E control unit evaluates information provided by various sensors concerning engine operating conditions, and from the information received generates a control signal for the electro-hydraulic actuator. Input signals include:
^ Overvoltage protection relay B+
^ Coolant temperature sensor
^ Electronic ignition control unit (EZL)
^ Air flow sensor position indicator
^ Throttle valve switch (idle and full load)
^ Electronic speedometer
^ Microswitch
^ Oxygen sensor
^ Intake air temperature sensor
^ Transmission range selector
^ Engine systems (MAS) control unit
The electro-hydraulic actuator regulates pressure in the lower chambers of the CIS-E fuel distributor which provides for the optimal fuel quantity. Furthermore, the CIS-E control unit provides output signals for operation of the:
^ The fuel pumps
^ Purge switchover valve
^ Idle control valve
^ Start valve
^ Transmission shift point delay
^ EGR switchover valve
^ Engine systems (MAS) control unit
^ On-Off ratio output (Diagnostic Socket)
^ "Check Engine" warning lamp
Warm-up Enrichment Chart:
AFTER-START AND WARM-UP ENRICHMENT (ELECTRO-HYDRAULIC ACTUATOR CONTROL)
With the throttle valve switch closed and engine temperatures below 68°F the after-start enrichment current to the electro-hydraulic actuator is 8 - 12 mA for a maximum of 8 seconds (increased current to electro-hydraulic actuator equals more fuel at the injectors). This provides for good initial start-up. If the engine temperature remains below 68°F the current will then drop to a warm-up constant of 3 - 7 mA and will remain fixed for a maximum of 2 minutes. Oxygen sensor control begins when the after-start enrichment has been canceled and the engine coolant temperature has reached 122°F. Oxygen sensor control will then continue until the next start-up cycle is repeated.
COLD START VALVE OPERATION
The cold start valve is activated by the CIS-E control unit based on coolant temperature information. Activation of the cold start valve occurs according to a pre-programed map in the CIS-E control unit and results in a pulsating injection of the cold start valve. Cold start injection does not occur above temperatures of 158°F.
RAISED 2ND - 3RD TRANSMISSION UP SHIFT
In order to have the catalytic converter reach its operating temperature more quickly during the warm-up phase, the automatic transmission 2nd - 3rd light throttle upshift point is raised at coolant temperatures below approx. 104°F. The upshift occurs at a higher vehicle speed, thus engine temperatures rise more rapidly.
IDLE SPEED CONTROL VALVE
When the ignition is switched to the run (ON) position and the engine is off the idle control valve is activated by a specific voltage from the CIS-E control unit which sets the valve opening, depending upon coolant temperature. After the engine is running the nominal engine speed is maintained between 720 RPM and 900 RPM depending upon inputs to the CIS-E control unit. Should there be an open or short circuit of the idle speed control valve circuit, or an interruption in the data exchange circuit between the CIS-E and EZL ignition control units, the power to the idle speed control valve is shut off. The ignition timing is also retarded to the extent that the idle speed increases only slightly.
HEATED O2 SENSOR
The CIS-E control unit controls the operation of the O2-sensor heater via the engine systems (MAS) control unit. The MAS control unit sends information regarding the O2-sensor heater current via the data exchange signal to the CIS-E control unit for on-board diagnostics.
AIR INJECTION SYSTEM CONTROL
The electromagnetic clutch of the air injection system pump is controlled by a coolant temperature dependent signal from the CIS-E control unit through the engine systems (MAS) control unit. The diagnostics of the CIS-E control unit checks the function of the entire system. The air pump is operated after each start for 5 seconds if the vehicle is stationary, the engine at operating temperature and at idle, and lambda control is operating. By means of the O2-sensor signal, it can be determined whether the air injection system is in operation. If a fault is recognized, it is stored in the on-board diagnostics of the CIS-E control unit.
EXHAUST GAS RECIRCULATION
The CIS-E control unit actuates the EGR switchover valve. Coolant temperature, air flow sensor position indicator, and throttle valve input are determining factors for CIS-E control of the EGR system. Furthermore, the diagnostics of the CIS-E control unit tests the function of the EGR system. During deceleration fuel cutoff the EGR switchover valve is actuated for 1.5 seconds. From the intake vacuum signal, which is measured by the ignition control unit, it can be determined whether the EGR system is functioning. If a fault is recognized, it is stored in the fault memory of the CIS-E control unit.
DIAGNOSIS AND TESTING
The CIS-E control unit can recognize and indicate malfunctions that have occurred in three different manners.
A. ON-BOARD DIAGNOSTIC CONNECTOR
While the engine is running, malfunctions that are encountered and recognized, such as, short circuits and implausible values are stored in the CIS-E control unit. Faults due to intermittent contacts are also recognized and stored as malfunctions. The stored faults can be extracted by use of the push-button and LED" or an impulse counter at the on-board diagnostic connector. The battery or the CIS-E control unit must not be disconnected before code extraction is completed or faults will be erased. On California models the "CHECK ENGINE" light in the instrument panel will illuminate if a fault is recognized in the emission control system. On Federal models the "CHECK ENGINE" light will illuminate only if there is a fault in the oxygen sensor circuit. Refer to DIAGNOSIS AND TESTING PROCEDURES.
B. ON-OFF RATIO WITH IGNITION ON
With the ignition switched (on), the input signals to the CIS-E control unit are tested with the components in a static condition. Stored faults are not indicated by this test. Only faults that are present in the system at the time of testing can be detected. This mode can be used for a quick test of the signals that are monitored. Refer to DIAGNOSIS AND TESTING PROCEDURES.
C. ON-OFF RATIO WITH ENGINE RUNNING
This test is to be conducted with the engine at normal operating temperatures an running. Signals to and from the control unit are tested in a dynamic state. An on-off ratio that is not oscillating (fixed) indicates a system malfunction. Refer to DIAGNOSIS AND TESTING PROCEDURES.