Файл: 92FWD_14.pdf

14 - 64 FUEL SYSTEMS

Engine Timing - The engine controller cannot detect an incorrectly indexed timing chain, camshaft sprocket and crankshaft sprocket. The engine controller also cannot detect an incorrectly indexed distributor. However, these could result in a rich or lean condition causing an oxygen sensor fault to be stored in the engine controller.

Cylinder Compression - The engine controller cannot detect uneven, low, or high engine cylinder compression.

Exhaust System - The engine controller cannot detect a plugged, restricted or leaking exhaust system.

Fuel Injector Malfunctions - The engine controller cannot determine if the fuel injector is clogged, the pintle is sticking or the wrong injector is installed. However, these could result in a rich or lean condition causing an oxygen sensor fault to be stored in the engine controller.

Excessive Oil Consumption - Although the engine controller monitors exhaust stream oxygen content when the system is in closed loop, it cannot determine excessive oil consumption.

Throttle Body Air Flow - The engine controller cannot detect a clogged or restricted air cleaner inlet or filter element.

Evaporative System - The engine controller will not detect a restricted, plugged or loaded evaporative purge canister.

Vacuum Assist - Leaks or restrictions in the vacuum circuits of vacuum assisted engine control sys-

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tem devices are not monitored by the engine controller. However, these could result in a MAP sensor fault being stored in the engine controller.

Engine Controller System Ground - The engine controller cannot determine a poor system ground. However, a fault code may be generated as a result of this condition.

Engine Controller Connector Engagement - The engine controller cannot determine spread or damaged connector pins. However, a fault code may be generated as a result of this condition.

HIGH AND LOW LIMITS

The engine controller compares input signal voltages from each input device with established high and low limits. If the input voltage is not within the limits and other fault code criteria are met, a fault code will be stored in memory. Other fault code criteria might include engine RPM limits or input voltages from other sensors or switches that must be present before a fault condition can be verified.

FAULT CODE DESCRIPTION

When a fault code appears, it indicates that the Engine Controller has recognized an abnormal condition in the system. Fault codes can be obtained from the Check Engine lamp on the Instrument Panel or from the Diagnostic Readout Box II (DRBII). Fault codes indicate the results of a failure but do not identify the failed component directly.

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SYSTEM TESTS

WARNING: APPLY PARKING BRAKE AND/OR BLOCK WHEELS BEFORE PERFORMING ANY TEST WITH THE ENGINE OPERATING.

OBTAINING FAULT CODES

(1)Connect DRBII to the diagnostic connector located in the engine compartment (Fig. 21 or Fig. 22).

(2)Start the engine if possible, cycle the trans mission selector and the A/C switch if applicable. Shut off the engine.

(3)Turn the ignition switch on, access Read Fault Screen. Record all the fault messages shown on the DRBII. Observe the check engine lamp on the instrument panel. The lamp should light for 2 seconds then go out (bulb check).

Fault code erasure: access erase fault code data.

STATE DISPLAY TEST MODE

The switch inputs used by the engine controller have only two recognized states, HIGH and LOW. For this reason, the engine controller cannot recognize the difference between a selected switch position versus an open circuit, a short circuit, or a defective switch. If the change is displayed, it can be assumed that the entire switch circuit to the engine controller is functional. From the state display screen access either State Display Inputs and Outputs or State Display Sensors.

STATE DISPLAY INPUTS AND OUTPUTS

Connect the DRB II tester to the vehicle and access the State Display screen. Then access Inputs and Outputs. The following is a list of the engine control system functions accessible through the Inputs and Outputs screen.

Park/Neutral Switch (automatic transmission only) Speed Control Resume

Brake Switch

Speed Control On/Off Speed Control Set A/C Switch Sense

Z2 Voltage Sense

S/C Vent Solenoid S/C Vacuum Solenoid A/C Clutch Relay Baro Read Solenoid Wastegate Solenoid Auto Shutdown Relay Radiator Fan Relay Purge Solenoid Check Engine Lamp

FUEL SYSTEMS 14 - 67

STATE DISPLAY SENSORS

Connect the DRB II tester to the vehicle and access the State Display screen. Then access Sensor Display. The following is a list of the engine control system functions accessible through the Sensor Display screen.

Battery Temp Sensor

Oxygen Sensor Signal

Coolant Temperature

Coolant Temp Sensor Throttle Position Minimum Throttle

Detonation (Knock) Sensor Signal Battery Voltage

MAP Sensor Reading

AIS Motor Position

Adaptive Fuel Factor

Barometric Pressure

Min Airflow Idl Spd Engine Speed

Fault #1 Key-On Info

Module Spark Advance Cyl 1 Knock Retard Cyl 2 Knock Retard Cyl 3 Knock Retard Cyl 4 Knock Retard Boost Pressure Goal Speed Control Target Fault #2 Key-on Info Fault #3 Key-on Info Speed Control Status Charging System Goal Theft Alarm Status Wastegate Duty Cycle Map Sensor Voltage Vehicle Speed

Oxygen Sensor State Baro Read Update MAP Gauge Reading Throttle Opening Total Spark Advance

CIRCUIT ACTUATION TEST MODE

The purpose of the circuit actuation test mode is to check for the proper operation of output circuits or devices which the engine controller cannot internally recognize. The engine controller can attempt to activate these outputs and allow an observer to verify proper operation. Most of the tests available in this mode provide an audible or visual indication of device operation (click of relay contacts, spray fuel, etc.). With the exception of an intermittent condition, if a device functions properly during its test, it can be assumed that the device, its associated wiring, and its driver circuit are in working order.

14 - 68 FUEL SYSTEMS

OBTAINING CIRCUIT ACTUATION TEST

Connect the DRB II tester to the vehicle and access the Actuators screen. The following is a list of the engine control system functions accessible through Actuators screens.

Stop All Tests

Ignition Coil #1

Fuel Injector #1

Fuel Injector #2

Fuel Injector #3

AIS Motor Open/Close Radiator Fan Relay A/C Clutch Relay Auto Shutdown Relay Purge Solenoid

S/C Serv Solenoids Alternator Field Tachometer Output Wastegate Solenoid Baro Read Solenoid All Solenoids/Relays ASD Fuel System Test Fuel Injector #4

THROTTLE BODY MINIMUM AIR FLOW CHECK PROCEDURE

(1)Warm engine in Park or neutral until the cooling fan has cycled on and off at least once.

(2)Hook-up timing check device and Tachometer.

(3)Disconnect the coolant temperature sensor and set basic timing to 12° BTDC 6 2° BTDC.

(4)Shut off engine. Connect harness connector to coolant temperature sensor.

(5)Disconnect the PCV valve hose from the nipple on the intake manifold.

(6)Attach Air Metering Fitting #6457 (0.125 in. orifice) to the intake manifold PCV nipple (Fig. 23).

(7)Disconnect 3/16 inch manifold vacuum purge line from the top of the throttle body. Cap the 3/16 inch throttle body nipple.

(8)Connect Diagnostic Readout Box II (DRB II).

(9)Restart engine. Allow engine to idle for at least one minute.

(10)Using the DRB II, access Min. Airflow Idle Spd. The following will then occur:

²AIS motor will fully close.

²Idle spark advance will become fixed.

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Fig. 23 Air Metering Fitting, Special Tool 6457

² Engine RPM will be displayed on Diagnostic Readout Box II (DRB II).

(11) Check idle RPM with tachometer, if idle RPM is within the below specification then the throttle body minimum airflow is set correctly.

IDLE SPECIFICATIONS

If the idle RPM is not within specification, replace the throttle body.

(12)Shut off engine.

(13)Remove Air Metering Fitting #6457 from the intake manifold PCV nipple. Reinstall the PCV valve hose.

(14)Remove DRB II.

(15)Disconnect timing check device and tachom-

eter.

(16)Reconnect purge line to throttle body.

IGNITION TIMING PROCEDURE

Refer to Group 8D Ignition System.

60-WAY ENGINE CONTROLLER WIRING CONNECTOR

Refer to the engine controller wiring connector diagram (Fig. 24) for information regarding wire colors and cavity numbers.