EGR System Dodge Diplomat I

DESCRIPTION

The exhaust gas recirculation (EGR) system allows a predetermined amount of exhaust gas to recirculate to the intake manifold. This dilutes the incoming air/fuel mixture.

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

OPERATION

Venturi vacuum control is used for EGR operation on 6-cylinder and V8 engines.

6-Cylinder & V8

Vacuum is tapped at the throat of the carburetor venturi or air flow sensor (EFI models) to provide control vacuum to the vacuum amplifier. This low amplitude vacuum signal is increased in the amplifier to a level which will operate the EGR valve.

A dump diaphragm compares venturi and manifold vacuum to prevent EGR operation at wide open throttle. EGR operation is determined primarily by the venturi signal, but is also effected by intake manifold vacuum and exhaust gas pressure.

COOLANT CONTROL EGR VALVE (CCEGR)

On 6-cylinder engines, the CCEGR valve is located in the cylinder head. On V8 engines, the CCEGR valve is located in the intake manifold.

Vehicles having a 6-cylinder or V8 engine are equipped with EGR delay system which consists of an electrical timer which in turn is connected to an engine mounted solenoid.

The purpose of the delay device is to not allow EGR function for a preset amount of time following engine start-up. The CCEGR valve will override this system if cold engine start is made. Amount of time delay differs between model applications.

The CTS is installed in the number 6 runner of the intake manifold on 6-cylinder engines and in the number 8 runner of the intake manifold on V8 engines.

When air/fuel mixture temperature is below 60°F (16°C), the switch closes. This prevents EGR timer and EGR valve operation. When air/fuel temperature is above 60°F (16°C), the switch opens. This again allows the EGR timer and EGR valve to operate.

Charge Temperature Switch (CTS) (6-Cylinder and V8). Scheme 37

Used with CTS, the CTS timer is not interchangeable with earlier models. Due to wiring harness and function changes, 3 timers are used. They are color coded Black, Orange or Red to correspond with various applications.

CCEGR VALVE

1. Remove CCEGR valve from vehicle. Place it in an ice bath to bring temperature of coolant sensing portion to below 40°F (4°C).
2. Attach a hand vacuum pump with gauge to the CCEGR nipple corresponding to the Blue stripe hose on 6-cylinder and V8 engines.
3. Apply vacuum of 10 in Hg. Observe gauge for 1 minute. There should be no more than 1 in. Hg drop in vacuum within this time. If so, replace CCEGR valve.

1. Before testing timer, check complete system for proper routing and connections of all hoses and wires. CAUTION: To avoid overload of timer, test light current draw should not exceed .5 amps. A typical automotive 12 volt tester is satisfactory for this test. A shop built tester using instrument panel size bulbs can also be used.
2. With ignition switch off, remove wiring connector from time delay solenoid valve. Connect a test light across wiring connector terminals just removed.
3. Start engine. Test light should come on and remain on for the amount of time as shown in color code application chart.
4. If light does not come on, remains on indefinitely, or does not react within the time limit shown, replace timer and repeat this test.

EGR TIMER SPECIFICATIONS

EGR TIMER SPECIFICATIONS

1. Make sure that all vacuum hoses are routed properly, correctly connected and not leaking. Disconnect electrical plug from solenoid valve.
2. Connect either solenoid terminal to a ground. Connect other terminal to positive battery terminal. This should activate the solenoid valve and shut off control vacuum to the EGR system.
3. You should hear a "click" from the solenoid as it is connected to the battery positive terminal.
4. 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 it does not, replace delay solenoid.

1. With engine cold and not running, connect a voltmeter to Gray wire at EGR solenoid. Set parking brake and start engine.
2. Voltmeter should read less than 1 volt. This 1 volt reading should remain until engine has reached normal operating temperature and electronic EGR schedule has timed out.
3. Solenoid will de-energize when EGR schedule has timed out. At this point voltage should read charging system voltage. If not, replace solenoid and repeat this test.
4. If voltmeter indicates charging system voltage before EGR schedule is complete, replace computer or externally mounted timer. NOTE: 5.2L 2-Bbl. Federal V8 engine has no coolant temperature thermal delay above 60°F (16°C) ambient temperature. It will follow EGR time delay schedule only.
5. If engine is restarted while still at normal operating temperature, EGR solenoid will only be energized for length of time delay schedule. It will then de-energize.

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.
2. 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.
3. 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.

TROUBLE SHOOTING

Note. All tests must be made with engine fully warm and running for at least 2 minutes.

EGR VALVE STEM DOES NOT MOVE ON SYSTEM TEST

1. Check for cracked, leaking, disconnected or plugged vacuum. Replace any defective hoses.
2. Connect an external vacuum source to EGR valve diaphragm. Apply at least 10 in. Hg to valve. If no valve movement occurs, Diaphragm is ruptured or stem is frozen. Replace EGR valve.
3. If valve opens 1/8" (3 mm), pinch off supply hose to check for diaphragm leakage. Valve should remain open for at least 30 seconds. If leakage occurs, replace EGR valve.

EGR VALVE STEM DOES NOT MOVE ON SYSTEM TEST, BUT OPERATES NORMALLY ON EXTERNAL VACUUM SOURCE

1. Disconnect CCEGR valve and by-pass valve with a short length of 3/16" tubing. If normal movement of EGR valve is restored, replace CCEGR valve.
2. On venturi vacuum type systems, disconnect Orange and Blue (or unstriped) hoses at time delay solenoid valve and by-pass valve with at short piece of tubing.
3. If normal EGR valve stem movement is restored, reconnect hoses to valve and disconnect electrical plug from solenoid. If EGR valve stem does not move, solenoid should be replaced.
4. If solenoid does move, timer should be further tested as previously described.
5. If plugged passages are suspected with the ported vacuum type system, carburetor should be removed and slots inspected and cleaned as necessary. Recheck for normal EGR operation.
6. If plugged passages are suspected with the venturi vacuum system, carburetor cleaner should be used to clean deposits from venturi passage. Use light air pressure to verify that passage is clean.
7. To check for defective vacuum amplifier (venturi vacuum systems), remove venturi vacuum signal hose from carburetor. With engine at idle, apply approximately 2 in. Hg vacuum to the signal hose.
8. Engine speed should drop at least 150 RPM and EGR valve stem should move 1/8" (3 mm) or more. If not, replace vacuum amplifier.

ENGINE WILL NOT IDLE, DIES ON RETURN TO IDLE OR ROUGH IDLE (EGR VALVE OPEN AT IDLE)

1. On venturi vacuum systems, disconnect and plug vacuum hose from EGR valve. If idle is unsatisfactory, replace EGR valve.
2. If idle is okay, reconnect hose to valve and disconnect hose from carburetor. If idle is okay, clean venturi tap. If idle not okay, replace vacuum amplifier.
3. On ported vacuum systems, disconnect an plug vacuum hose from EGR valve. If idle is not okay, replace EGR valve.
4. If idle is still rough, install vacuum gauge on ported signal tap. If more than 1" of vacuum is present, check idle setting. If vacuum is okay, check linkage and carburetor for binding.

ENGINE WILL NOT IDLE, DIES ON RETURN TO IDLE OR ROUGH IDLE (EGR VALVE CLOSED AT IDLE)

If removal of vacuum hose from EGR valve does not correct rough idle, remove EGR valve and inspect to ensure that poppet is seated. Clean deposits from valve or replace EGR valve if necessary.