EGR System Dodge Daytona I

DESCRIPTION

Exhaust Gas Recirculation (EGR) system is used on all models except 2.2L turbo. The EGR allows a predetermined amount of exhaust gas to recirculate to the intake manifold, diluting the incoming air/fuel mixture.

This diluting of the air/fuel mixture reduces peak combustion temperatures. The lower combustion temperature reduces emissions of oxides of nitrogen (NOx).

California models use an on-board diagnostics for the EGR system. The diagnostic system adds a solenoid to the vacuum line to the EGR valve.

OPERATION

A backpressure type EGR system is used on 2.2L and 2.5L throttle body fuel injected engines. The backpressure transducer measures the amount of exhaust backpressure and varies the strength of the vacuum signal to the EGR valve. The signal vacuum is bled off into the atmosphere when exhaust backpressure to the EGR drops below a calibrated value.

On 5.2L engines, an electronically controlled EGR system is used. The system consists of Spark Control Computer (SCC), Charge Temperature Sensor (CTS), EGR solenoid and EGR delay system (4-Bbl. models).

Venturi vacuum signal is used to control EGR operation on 5.2L 4-Bbl. engines. Because of the low strength of venturi vacuum signal, a vacuum amplifier is used to increase vacuum signal strength to operate the EGR valve. This system uses an EGR solenoid to control EGR valve operation. Some vehicles are equipped with an EGR delay system to prevent EGR operation for about 60 seconds after ignition is turned on.

On California models, an on-board diagnostic system checks the entire EGR system for failures and is activated and monitored only during selected engine/driving conditions to avoid misdiagnosis.

When monitored, the EGR solenoid is energized, disabling the EGR. The O2 feedback system is monitored to see if a change occurs. The mixture should go lean and the system will try to richen the mixture. The SMEC monitors EGR system performance and registers a fault code if the system has failed or effectiveness has lessened, and turns on the "CHECK ENGINE" light.

2.2L & 2.5L TBI, 3.0L MPFI & 5.2L 2-Bbl. Engines

As the throttle blade opens, a slotted port in the carburetor base or throttle body is exposed to an increasing percentage of manifold vacuum. This port is connected through an external nipple to an EGR solenoid and/or transducer and then to the EGR valve. The flow rate is dependent on manifold vacuum, throttle position and exhaust gas backpressure.

Scheme 17

Scheme 18

5.2L 4-Bbl. Engine

The venturi vacuum control system utilizes a vacuum tap at the throat of the carburetor venturi to provide a vacuum control signal. Because of the low signal strength, it is necessary to use a vacuum amplifier to increase vacuum to the level that will operate the EGR valve.

Elimination of EGR at wide open throttle is accomplished by a dump diaphragm which compares venturi and manifold vacuum to determine when wide open throttle is achieved. At wide open throttle, the internal reservoir is dumped, limiting output to the EGR valve to manifold vacuum.

The valve opening point is set above the manifold vacuum available at wide open throttle, permitting the valve to be closed at wide open throttle. This system is dependent primarily on engine intake airflow, as indicated by the venturi signal, and is also affected by intake vacuum and exhaust pressure.

Scheme 19

The Charge Temperature Sensor (CTS) is installed in the No. 8 intake manifold runner. The sensor signals the computer when to operate the air switching, EGR and spark advance systems.

Some vehicles are equipped with an EGR delay system that is incorporated in the Spark Control Computer (SCC) and controls the EGR solenoid. The solenoid is connected between the carburetor venturi vacuum signal nipple and vacuum amplifier by hoses. The system is designed to prevent EGR operation for about 60 seconds after the ignition is turned on.

California Models

On-board diagnostics for EGR system are part of vehicle diagnostic system. If a malfunction is indicated by the "CHECK ENGINE" light and a fault code for EGR system is stored, see appropriate article in the COMPUTERIZED ENGINE CONTROLS section.

EGR SOLENOID

1. Ensure that all vacuum hoses are routed properly, correctly connected and not leaking. Disconnect electrical plug from solenoid valve. Connect either solenoid terminal to ground. Connect other terminal to positive battery terminal.
2. This should activate the solenoid valve and shut off control vacuum to the EGR system. You should hear a "click" from the solenoid as it is connected to battery positive terminal.
3. To test valve operation, start engine and let it idle. Raise engine speed to about 2000 RPM. Watch EGR control valve stem. EGR control valve stem should move. If stem does not move, replace solenoid.

SYSTEM FUNCTIONAL CHECK

Note. To ensure proper operation of the EGR system all passages and moving parts must be free from plugging or sticking as a result of deposits. Clean or replace components and hoses as necessary.

2.2L & 2.5L (Except Turbo)

1. Warm engine to operating temperature. Attach a tachometer to the engine. Run engine at idle in Neutral an additional 70 seconds. Accelerate the engine abruptly to approximately 2000 RPM, but not over 3000 RPM.
2. During this procedure, check the EGR valve stem for movement. Visible movement of the valve stem should occur. Repeat test to confirm operation. Movement of the stem indicates that the control system is functioning correctly.
3. If EGR valve stem does not move, check for cracked, leaking, disconnected or plugged hoses. Verify correct hose routing. Disconnect hose harness from EGR valve/transducer and connect a vacuum pump to harness.
4. Start engine and raise engine speed to 2000 RPM and hold. Apply 10 in. Hg vacuum to EGR while checking for EGR valve movement. If no movement occurs, replace EGR valve/transducer assembly.
5. If valve opens approximately 1/8", hold vacuum constant and check for valve diaphragm leakage. Valve should remain open for at least 30 seconds. If leakage occurs, replace valve/transducer assembly. If valve is okay, check control system.
6. If EGR valve stem did not move in step 2), but operates normally on external vacuum source, remove throttle body and check port in throttle bore for blockage. Use a solvent to remove deposits and check flow with light air pressure. Normal operation should be restored.
7. If engine will not idle, or if engine stalls or idles very rough or slow, check for leaking EGR valve. With engine running, remove vacuum hose from EGR valve. If removing the vacuum hose does not correct rough idle, remove EGR valve/transducer assembly. Check valve for proper seating. Replace assembly as necessary.
8. Also check EGR-to-intake manifold tube for leak. On 2.2L and 2.5L models, loosen tube and tighten to 25 ft. lbs. (34 N.m). On 3.0L models, remove tube and inspect gasket. Tube end should be uniformly indented on gasket, with no signs of leakage.
9. If there are signs of leakage, replace gaskets and tighten flange nuts to 17 ft. lbs. (23 N.m). If leak persists, replace EGR tube and gaskets.

5.2L

1. Warm engine to operating temperature, and let idle at least 2 minutes after warm-up in Park or Neutral. Disconnect hose at EGR valve and attach a vacuum gauge to hose.
2. Open throttle quickly several times. A fluctuation of several in. Hg of vacuum should be observed during throttle movement. Disconnect vacuum gauge. Attach a vacuum pump to the EGR valve. With engine running, apply 10 in. Hg vacuum to the valve. The engine speed should drop several hundred RPM, stumble or stall.
3. Disconnect the vacuum pump and reconnect vacuum hose to EGR valve. If system operated as described, system is operating correctly. If system did not operate as described, remove connector from charge temperature sensor. Using an ohmmeter, check sensor resistance. See CHARGE TEMPERATURE SENSOR RESISTANCE table. CHARGE TEMPERATURE SENSOR RESISTANCE Temperature °F (°C) Resistance: Ohms -40 to 20 (-40 to -7) 382,000-22,000 50-100 (10-38) 36,000-3300 140-245 (60-118) 3900-176
4. If resistance is not as specified, replace sensor. If resistance is okay, repair wiring between computer and sensor for an open or short circuit. With engine cold and not running, connect a voltmeter to Gray wire at EGR solenoid. Set parking brake and start engine.
5. With engine temperature less than 70°F (21°C) for 2-Bbl. models and less than 50°F (10°C) for 4-Bbl. models, voltmeter should read zero to one volt. If voltage reading is more than one volt, turn engine off. Disconnect computer 12-pin connector. Connect voltmeter to connector cavity No. 7 and ground. Turn ignition switch to "RUN" position.
6. Voltmeter reading should be within one volt of battery voltage. If voltage reading is okay, replace computer. If there is zero volts, repair open circuit in wiring harness to ignition switch.
7. On 5.2L 4-Bbl. models, remove venturi vacuum hose from carburetor. With engine at idle, apply 1-2 in. Hg vacuum to vacuum hose. Engine speed should drop at least 150 RPM and EGR valve stem should visibly move at least 1/8".
8. If this does not occur, replace vacuum amplifier. If system works properly, check carburetor for plugged vacuum tap. Use carburetor cleaner to clean passage and blow through with compressed air.
9. On 5.2L 2-Bbl. models, remove ported vacuum hose from carburetor. With engine at idle, apply at least 5 in. Hg vacuum to vacuum tap on carburetor. If vacuum does not bleed off, check carburetor for plugged vacuum tap. Use carburetor cleaner to clean passage and blow through with compressed air. NOTE: DO NOT use drill or wire to clean carburetor control passages, as calibration of control orifices may be changed, resulting in unsatisfactory vehicle operation.
10. On 5.2L 4-Bbl. models, if engine will not idle, or if engine stalls or idles very rough or slow, disconnect and plug EGR vacuum hose. Recheck idle. If idle is now okay, replace amplifier. If vacuum hose removal does not correct problem, remove EGR valve. Inspect valve and clean as necessary. Replace EGR valve as necessary.
11. If there is poor Wide Open Throttle (WOT) performance, disconnect and plug EGR hose. Road test vehicle. If performance is restored, replace amplifier.

EGR VALVE

1. Inspect valve for deposits with particular attention to the poppet and seat area. If deposits exceed a thin film, valve should be cleaned. Cleaning is aided by applying a liberal amount of manifold heat control solvent, or equivalent, to the poppet and seat area, allowing deposits to soften. CAUTION: Extreme care should be taken when using solvent cleaners to prevent spilling of solvent on valve diaphragm.
2. Use an external vacuum source to open poppet and then scrape deposit from this area. If wear of stem or other moving components is noted, valve should be replaced.

Note. Do not push valve stem manually, use an external vacuum source only.