Fuel Injection System - Multi-Point Dodge Daytona I

COMPONENT TESTING

Note. See TESTING .

DESCRIPTION

The Chrysler Multi-Point Electronic Fuel Injection system is an electronically controlled system which combines electronic fuel injection and electronic spark advance. The main sub-systems consist of air induction, fuel delivery, fuel control, emission control, Single Module Engine Controller (SMEC) and data sensors. The SMEC is utilized in place of the former logic and power modules.

Multi-Point Fuel Injection Components (2.2L Turbo). Scheme 1

Multi-Point Fuel Injection Components (3.0L). Scheme 2

AIR INDUCTION

On turbo models, air is drawn through the air cleaner and forced through the throttle body by the turbocharger. Wastegate is controlled by the SMEC and can increase turbo boost to higher levels for brief periods of time. The amount of air entering the engine is controlled by a cable operated throttle valve in the throttle body.

On all models, the throttle body houses the Throttle Position Sensor (TPS) and Automatic Idle Speed (AIS) motor. The TPS is an electrical resistor which is connected to the throttle valve. The TPS transmits a signal to the SMEC in relation to throttle valve angle. From this signal, the SMEC calculates fuel injector "on" time to provide adequate air/fuel mixture.

The AIS motor controls the flow of air through the throttle body during engine idle. The motor opens and closes an air by-pass on the back of the throttle body to increase or decrease idle speed as engine load varies. The SMEC monitors the AIS motor and issues a change command to the injectors to increase or decrease the amount of fuel injected.

FUEL DELIVERY

Fuel is drawn through a filter sock on one end of the fuel pump and is forced out the opposite end. Two check valves are used. One relieves internal fuel pump pressure and regulates maximum fuel pressure output.

The other check valve, located near pump outlet, restricts fuel flow in either direction when pump is not running. Fuel not used by the engine is returned to the tank by a fuel return line.

Power to the fuel pump is supplied through the Automatic Shut-Down (ASD) relay of the SMEC. When the SMEC receives a signal from the distributor during engine cranking, it grounds ASD motor, closing ASD contacts. When contacts are closed, power is applied to fuel pump.

When distributor signal is lost, the SMEC opens the ASD motor, which cuts power supply to fuel pump. This prevents fuel flow should the vehicle be involved in an accident or if engine stalls.

FUEL INJECTORS

The fuel injectors are an electric solenoid powered and controlled by the SMEC. The SMEC determines when and how long the injector should operate. When an electric current is supplied to the injector, the armature and pintle move a short distance against a spring, opening a small orifice. Since fuel is under high pressure a fine spray is developed.

SINGLE MODULE ENGINE CONTROLLER (SMEC)

The Single Module Engine Controller (SMEC), performs the functions formerly performed by the logic module and power module. The SMEC contains necessary circuits to operate the ignition coil, fuel injector, and alternator field. It computes the fuel injector pulse width, spark advance, ignition coil dwell, idle speed, purge, cooling fan operation and alternator charge rate. The SMEC contains a voltage converter which converts battery voltage to 8 volts output.

Manifold Absolute Pressure (MAP) Sensor

The MAP sensor, located in the engine compartment on the right shock tower, monitors manifold vacuum via vacuum line attached to throttle body. The MAP sensor supplies the SMEC with an electrical signal which indicates manifold vacuum and barometric pressure. This information helps to determine air/fuel ratio.

Oxygen Sensor

Oxygen sensor is mounted in exhaust manifold or turbo outlet. The oxygen sensor monitors oxygen content of exhaust gases and generates voltage signals proportional to oxygen content.

Voltage signal to the SMEC is low when oxygen content of exhaust gases is high, indicating lean air/fuel mixture. If oxygen content decreases (mixture becomes richer), signal voltage will increase.

Charge & Coolant Temperature Sensors

Two temperature sensors are used on this system. The charge temperature sensor, which is mounted in the intake manifold, measures temperature of incoming air/fuel mixture. The coolant temperature sensor, which is mounted in thermostat housing, measures temperature of engine coolant.

Information provided by these 2 sensors allows the SMEC to demand slightly richer air/fuel mixtures and higher idle speeds during cold engine operation.

If coolant temperature sensor should fail, the information supplied by the charge temperature sensor is sufficient to determine engine operating temperature and engine warm-up cycles until the coolant temperature sensor can be replaced.

Throttle Position Sensor (TPS)

The TPS is an electric resistor which is activated by throttle shaft movement. It is mounted on the throttle body and senses angle of throttle blade opening.

A voltage signal is produced by the sensor which varies with this angle. This signal is transmitted to the SMEC where it is used to adjust air/fuel ratio during acceleration, deceleration, idle, and wide open throttle.

Detonation Sensor

The detonation sensor is mounted on intake manifold. Detonation is converted into an electrical signal which is sent to the SMEC. The SMEC will change spark advance and/or boost as needed.

Engine Switches

Several switches provide operating information to the SMEC. These include neutral safety, A/C clutch, brake light and idle switches. When the SMEC senses one or more of these switches is on, the AIS motor will receive a signal to increase idle speed.

AUTOMATIC IDLE SPEED MOTOR (AIS)

The automatic idle speed motor is operated by the SMEC. Data from throttle position sensor, speed sensor, coolant temperature sensor, and various switch operations, are used by the SMEC to adjust engine idle. The AIS adjusts the air portion of the air fuel mixture through an air by-pass as an increase or decrease is needed.

Purge Solenoid

Purge solenoid is located in solenoid bank next to MAP sensor. If engine temperature is below 145°F (61°C), the SMEC energizes purge solenoid by providing ground circuit. This keeps vacuum from charcoal canister valve. When purge solenoid ground is removed, vacuum flows to canister purge valve and fuel vapors are removed through throttle body.

EGR Diagnostic Solenoid (3.0L California Models Only)

The EGR diagnostic solenoid is located in solenoid bank on 3.0L California models only.

The purge solenoid is operated by the SMEC. When engine temperature is below 145°F (61°C) the SMEC closes the solenoid and prevents manifold vacuum or pressure from reaching EGR valve. When prescribed temperature is reached, the SMEC will de-energizing solenoid.

Wastegate Control Solenoid (Turbo Only)

The wastegate control solenoid is located in solenoid bank. Maximum turbocharger boost is controlled by the SMEC, which changes duty cycle of wastegate solenoid. Boost is then varied to operating conditions.

Barometric Pressure Solenoid (Turbo Only)

The barometric pressure read solenoid is controlled by the SMEC. The solenoid is in the MAP sensor vacuum line, next to the MAP sensor. The solenoid controls whether manifold pressure or atmospheric pressure is supplied to the MAP sensor.

PRELIMINARY CHECKS

Most driveability problems in the multi-point EFI system are the result of faulty wiring or loose and/or leaking hose connections. To avoid unnecessary testing, check the following before beginning trouble shooting procedures. A preliminary visual check should include

1. Air ducts at air cleaner, turbocharger and throttle body.
2. All electrical connections at components.

Check vacuum lines for tight, leak-free connections in these areas

1. Throttle body.
2. Solenoid bank.
3. Vapor canister.
4. PCV valve to turbocharger vacuum port.
5. Backpressure transducer.
6. MAP sensor.

Ensure the following electrical connectors are properly attached

1. 14-pin and 60-pin connector at SMEC.
2. Connectors at ASD relay.
3. Connectors at solenoid bank.
4. Speed/distance sensor connector (in-line with speedometer cable).
5. Charge temperature sensor connector.
6. Throttle body connector.
7. Fuel injector connectors.
8. O2 sensor connector.
9. Coolant temperature sensor connector.
10. Distributor connectors.
11. Connector at detonation sensor.
12. Radiator fan relay connectors.
13. Ground eyelet mounting onto intake manifold.

Fuel System Pressure Release

1. Fuel pressure must be fully released before opening fuel loop or removing any fuel carrying components. To release pressure in tank, open fuel tank cap slowly.
2. To release remaining pressure in system, disconnect 2-way connector from any fuel injector. Using jumper wire, connect either injector terminal to ground. Connect remaining injector terminal to positive battery terminal.
3. DO NOT keep injector connected in this way for more than 10 seconds. Fuel pressure should be fully released.

Fuel System Pressure Test

1. Release fuel system pressure. Remove cover from service valve on fuel rail. Connect Fuel Pressure Gauge (C-3292) and Adapter Hose (C-4799) to service valve. Turn ignition on. Depress Actuator Test Mode (ATM) button on Diagnostic Readout Box (C-4805) to activate fuel pump.
2. Check reading on testers after system is pressurized. Correct pressure reading should be 55 psi (3.9 kg/cm 2 ) for turbo models and 48 psi (3.3 kg/cm 2 ) for 3.0L models.

SYSTEM DIAGNOSIS

The throttle body fuel injection system is equipped with "On-Board Diagnosis," which has a self-diagnostic capability that checks several circuits. If abnormal signals occur often enough to indicate a valid problem, the SMEC will store the fault code for later display. If problem is either repaired or disappears by itself, the SMEC will remove the fault code after 50-100 engine starts.

Depending on fault code, the "Check Engine" light may illuminate. Located on instrument panel, this light informs operator that malfunction in system has occurred and immediate service is required.

The SMEC will attempt to compensate for failure of a component by using input from remaining sensors. If the check engine light comes on or certain driveability and engine performance problems exist, the source of these difficulties may be determined by displaying and recording fault codes. Check FAULT CODES to determine questionable circuits.

Displaying Fault Codes

1. Connect Diagnostic Readout Box (C-4805) to diagnostic connector, located near the SMEC. If possible, start engine and cycle transmission selector and A/C switch (if equipped). Turn engine off.
2. DO NOT restart engine. Turn key on and off 3 times, completing sequence in 5 seconds. Record all fault codes as displayed by diagnostic readout box.
3. If using "Check Engine" light for display, use same sequence to initiate display. "Check Engine" light will first illuminate for 3 seconds to check bulb. After bulb check, "Check Engine" light will display fault codes by series of flashes.
4. There are short pauses between flashes and longer pauses between digits, with 4 second pause between codes. For example, fault Code 23 would be displayed by flash, flash, pause, flash, flash, flash. After 4 second pause, next numerically higher fault code will be displayed.

Code 88

First code to be displayed. This code must be displayed for remaining fault codes to be valid. It indicates start of fault code display.

Code 11

Distributor signal circuit. Displayed if no distributor signal has been received by SMEC since restoration of battery voltage.

Code 12

Loss of memory standby power. Displayed if battery feed to SMEC has been interrupted.

Code 13

MAP sensor pneumatic system. Displayed if sensor vacuum level does not change between cranking and when engine starts. "Check Engine" light will illuminate.

Code 14

MAP sensor electrical system. Displayed if MAP sensor signal is outside of .02-4.9 volt range. "Check Engine" light will illuminate.

Code 15

Vehicle speed/distance sensor circuit. Displayed if sensor indicates less than 2 MPH when vehicle is moving. Code valid only if sensed while vehicle is moving.

Code 16

Loss of battery voltage. "Check Engine" light will illuminate.

Code 17

Engine cooling system. Appears when engine coolant temperature does not reach 160°F (71°C) within 20 minutes of engine start.

Code 21

Oxygen sensor circuit. Displayed if no oxygen sensor signal received for more than 22 seconds when in closed loop.

Code 22

Engine coolant temperature sensor circuit. Displayed if temperature sensor indicates an incorrect temperature or a temperature that changes too quickly. "Check Engine" light will illuminate.

Code 23

Charge temperature sensor. Displayed if charge temperature sensor indicates an incorrect temperature or a temperature that changes too quickly. "Check Engine" light will illuminate.

Code 24

TPS circuit. Displayed if sensor signal is either below .16 volts or above 4.7 volts. "Check Engine" light will illuminate.

Code 25

AIS control circuit. Displayed if proper voltage from AIS system is not present. Open wiring harness or motor will not activate this code.

Code 26

Injectors No. 1 and 2 control circuit. Displayed if injectors No. 1 and 2 do not fire correctly.

Code 27

Injectors No. 3 and 4 control circuit. Displayed if injectors No. 3 and 4 do not fire correctly.

Code 31

Canister purge solenoid circuit. Displayed if solenoid does not turn on and off when it should.

Code 32

Problem in EGR diagnostics. (California only).

Code 33

A/C cut-out relay. Displayed if relay does not turn on and off when it should.

Code 34

Problem in speed control solenoid driver circuit.

Code 35

Radiator fan relay circuit. Displayed if relay does not turn on and off as it should.

Code 36 (Turbo Models)

Wastegate control solenoid. Displayed if solenoid does not turn on and off when it should. "Check Engine" light will illuminate.

Code 37

Displayed when barometric read solenoid does not turn on and off when it should (2.2L turbo only), or indicates problem in part throttle unlock solenoid driver circuit (3.0L only).

Code 41

Alternator field control. Displayed if field control fails to switch properly.

Code 42

ASD relay circuit. Displayed if control voltage of relay pull-in coil is not correct.

Code 43

Spark control interface. Displayed if spark control interface fails to switch properly.

Code 44

Loss of voltage to SMEC.

Code 46

Battery voltage sensing circuit. Displayed if battery sensing voltage is too high. "Check Engine" light will illuminate.

Code 47

Battery voltage sensing circuit. Displayed if battery sense voltage is too low.

Code 51

Lean operation of oxygen feedback system.

Code 52

Rich operation of oxygen feedback system.

Code 53

Internal problem with SMEC.

Code 54

Distributor synch pick-up circuit. Displayed if there is no distributor synch signal.

Code 55

This is the end of message code. This code will always appear after all other fault codes have been displayed.

SWITCH TEST

1. Ensure all input switches are off. After code 55 is displayed for "end of message" in diagnostic mode, watch display while operating various switches. Digital display MUST change if switches are working.
2. Check brake pedal switch by applying and releasing brake pedal. Check A/T gear selector switch by moving lever from Park to Reverse to Park. Check A/C switch by turning blower switch to "ON" and "OFF" positions (only valid when A/C dampened pressure switch is closed).

ACTUATOR TEST MODE (ATM)

Note. This test can only be performed with Diagnostic Readout Box (C-4805).

1. Put system into diagnostic test mode. Wait for code 55 to appear on display screen. Press ATM button on tool to activate display. If specific ATM test is desired, hold ATM button down until test code appears.
2. The computer will continue to turn selected circuit on and off for up to 5 minutes or until ATM button is pressed or ignition is turned off. If ATM button is not pressed, computer will continue to cycle selected circuit for 5 minutes and then shut system off. Turning ignition off will also shut test mode off.

ACTUATOR TEST DISPLAY CODES

PRECAUTIONS

Before removing any fuel system components, system pressure must be relieved. It is not necessary to remove throttle body from intake manifold to remove components.

If any components such as hoses or clamps are replaced, ensure they are replaced with components designed for EFI use. Always reassemble throttle body components with new "O" rings and seals.

Removal & Installation

Disconnect negative battery cable and throttle body wiring connector. Remove 2 screws mounting throttle position sensor to throttle body. Remove throttle position sensor off throttle shaft. To install, remove removal procedure.

1. Disconnect negative battery cable. Remove screws attaching air cleaner to throttle body. Loosen hose clamp and remove air cleaner adapter. Remove accelerator, speed control and transmission kickdown cables and return spring.
2. Remove throttle cable bracket from throttle body. Disconnect electrical connector. Disconnect vacuum hoses from throttle body. Loosen screws attaching throttle body to intake manifold. Remove throttle body. To install, reverse removal procedure.

Removal

Disconnect negative battery cable. Disconnect throttle body wiring connector. Remove 2 AIS motor-to-throttle body screws. Remove AIS motor from throttle body. Ensure "O" ring is on AIS motor.

Installation

1. New AIS motor is equipped with "O" ring. If pintle is longer than one inch (25 mm) it must be retracted using ATM test code No. 3.
2. Position AIS motor into throttle body. Install 2 mounting screws and tighten to 17 INCH lbs. (2 N.m). Connect wiring connector to AIS motor and reconnect negative battery cable.

With fuel tank removed from vehicle, use hammer and brass punch to carefully tap lock ring counterclockwise and release pump. Remove fuel pump and "O" ring seal from tank. Discard old seal. To install, reverse removal procedure, making sure seal area is clean. Take care not to overtighten pump.

1. Release fuel system pressure. Disconnect negative battery cable. Remove air cleaner assembly. Disconnect knock sensor and fuel injector wiring connectors. Loosen supply hose clamp and return hose clamp at fuel pressure regulator and remove hoses.
2. Remove fuel pressure regulator vacuum hose from regulator. Remove fuel pressure regulator-to-fuel rail attaching nuts. Remove fuel pressure regulator from fuel rail. Remove PCV vacuum harness and vacuum vapor harness from intake manifold.
3. Remove fuel rail to valve cover bracket screw. Disconnect knock sensor connector. Remove fuel rail-to-intake manifold attaching screws. Remove fuel rail and injector assembly so injectors come straight out of ports. Use care to not damage "O" rings. Remove fuel rail assembly from vehicle.
4. Cover injector ports with a rag while injectors are serviced. DO NOT remove fuel injectors until fuel rail assembly has been removed from vehicle.

Fuel Injectors & Rail Assembly. Scheme 3

1. Seat injectors in cups (if removed) and install lock rings. Ensure injector holes are clean. Lube injector "O" rings with drop of oil. Install injector assemblies in sockets. Install 2 attaching bolts and ground straps. Tighten bolts to pull fuel rail into place evenly with each injector in its own hole.
2. To complete installation, reverse removal procedure. All wiring, hoses and ground straps must be in original positions. Use ATM tester or start vehicle to check for fuel leaks.

Remove injector wiring connector from injector. Position fuel rail assembly so fuel injectors are accessible. Remove injector lock ring off fuel rail and injector. Pull injector straight out of fuel rail receiver cup.

Inspection

Check injector "O" ring for damage. If injector is to be reused, install a protective cap over the injector tip to prevent damage.

Lubricate injector "O" ring with oil before installation. Install injector top end into fuel rail cup. Use care to not damage "O" ring during installation. Install injector lock ring. To complete installation, reverse removal procedure.

1. Perform fuel system pressure release procedure. Disconnect negative battery cable. Remove vacuum hose from fuel pressure regulator. Loosen fuel return hose clamp at fuel pressure regulator and remove hose. Wrap a rag around hose to collect fuel spillage.
2. Remove fuel pressure regulator attaching nuts. Remove fuel pressure regulator from rail. Before installation of regulator, lubricate "O" ring with a drop of oil. To install, reverse removal procedure.

Remove air cleaner duct from SMEC. Remove battery. Remove mounting screws and electrical connectors. To install, reverse removal procedure.

Using Sensor Socket (C-4907), remove oxygen sensor from exhaust manifold. Using 18 mm x 1.5 x 6E tap, clean threads in exhaust manifold. New oxygen sensors come with anti-seize on threads. If old sensor is to be reused, coat threads with anti-seize compound. Tighten oxygen sensor to 20 ft. lbs. (27 N.m).

SPECIFICATIONS

Note. Specifications not available. For reference view of components (Scheme 1)and (Scheme 2).

MPFI System Wiring Diagram (2.2L Turbo). Scheme 4

MPFI System Wiring Diagram (3.0L). Scheme 5

See also:
• TESTING