EGR Function Testing - Chrysler Trucks Dodge Caravan II

Ported EGR System

1. Check vacuum lines for correct routing. Warm engine to normal operating temperature. Some models with EGR delay timers must operate at least 1-2 minutes for EGR to function.
2. While watching EGR pintle, abruptly accelerate engine to 2000-3000 RPM. EGR pintle should open at least 1/8". If EGR pintle does not move, check for cracked, leaking, disconnected or plugged vacuum hose. Verify correct vacuum hose routing.
3. Connect a hand-held vacuum pump to EGR valve. Idle engine and gradually apply a minimum of 10 in. Hg. EGR valve stem should move and engine speed should drop at least 150 RPM.

Sub-EGR Control System

Check vacuum lines for correct routing. Disconnect Green-stripe vacuum hose from carburetor. Attach a vacuum pump to vacuum hose. With engine idling, manually open sub-EGR control valve. Apply 6 in. Hg to EGR valve and engine should run rough. Reconnect vacuum hoses.

EGR Valve/Backpressure Transducer Assembly

1. Check vacuum hoses for correct routing. Warm engine to normal operating temperature. Connect a vacuum pump to EGR valve. With engine idling, slowly apply 2-3 in. Hg. Engine RPM should drop when vacuum is applied.
2. Disconnect vacuum pump from EGR valve. Connect vacuum gauge to EGR vacuum supply hose. Start engine and raise engine speed to 2000 RPM. Vacuum gauge should read about 5 in. Hg. If test results are as specified, system is okay.

Vacuum Amplifier (If Equipped)

1. Ensure manifold vacuum is present. With engine warm and at curb idle, connect vacuum gauge to hose on vacuum amplifier leading to venturi vacuum port. Attach a vacuum pump to hose, and apply 2 in. Hg.
2. Disconnect EGR delay timer hose (if equipped). EGR valve should open and engine speed should drop at least 150 RPM. If engine speed does not drop, replace vacuum amplifier.

Backpressure EGR Valve

Check vacuum hoses for correct routing. Warm engine to normal operating temperature. Raise engine speed to 2000-300 RPM. Apply about 8-10 in. Hg to EGR valve. Engine RPM should drop. If test results are as specified, system is okay. If engine RPM does not drop, but EGR valve opens, check for plugged EGR ports. If EGR valve does not open, replace EGR valve.

EGR System

1. Check vacuum hoses for correct routing. Warm engine to normal operating temperature. Engine coolant temperature must be greater than 150°F (65°C).
2. Apply parking brake. Place transmission in Neutral with throttle in idle position. Suddenly increase engine RPM to 2000-3000 RPM, while noting movement of EGR valve stem. DO NOT exceed 3000 RPM.
3. Valve stem in EGR valve should move when engine RPM is increased. Repeat test procedure several times to ensure correct operation. If valve stem does not move, check EGR system and vacuum supply.

EGR Valve Flow

1. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. Start engine and allow engine to idle. Slowly apply vacuum to EGR valve.
2. Engine idle speed should begin to decrease, or engine may stall, when applied vacuum reaches 5.0 in. Hg on RWD trucks, or 2.0-3.5 in. Hg on FWD vans. This indicates EGR valve is operating properly. If EGR valve does not operate correctly, remove EGR valve and check for restricted exhaust passages.

EGR System Operation

1. Inspect all vacuum hoses to throttle body, EGR valve and EGR solenoid. Repair vacuum hoses if leaking or restricted. EGR solenoid is located on top of EGR backpressure transducer.
2. Ensure hoses are properly routed between EGR valve, EGR solenoid and EGR backpressure transducer. Ensure electrical connector is firmly installed on EGR solenoid.
3. Connect scan tool to Data Link Connector (DLC) located below driver's side of instrument panel. For additional information on locating DLC and scan tool usage, see TESTS W/CODES article in ENGINE PERFORMANCE.
4. Using scan tool, check EGR system by performing specified NO TROUBLE CODE (NTC) test. See TEST NTC-13A CHECKING EGR SYSTEM in TESTS W/CODES article in ENGINE PERFORMANCE.
5. After checking EGR system with scan tool, proceed to EGR valve gas flow test, EGR valve leakage test and EGR backpressure transducer test.

EGR Valve Gas Flow Test

1. Test may be used to determine if exhaust gas is flowing through EGR valve, EGR tube, intake manifold and exhaust manifold. Start engine and warm engine to normal operating temperature. Shut engine off.
2. Note location of hoses on EGR valve and EGR backpressure transducer. Hose at top of EGR valve supplies vacuum to EGR valve. Hose on signal tube at bottom of EGR valve supplies exhaust pressure to EGR backpressure transducer.
3. Disconnect hose from top of EGR valve. Start engine and allow engine to idle. Using vacuum pump, slowly apply 5 in. Hg of vacuum on hose fitting at top of EGR valve and note engine operation. With vacuum applied, engine idle speed should decrease and/or engine may stall to indicate exhaust gas is flowing through EGR tube.
4. If engine idle speed decreases and/or engine stalls, go to step 7). If engine idle speed does not decrease and/or engine stalls, this indicates exhaust gas is not flowing through EGR system. Shut engine off.
5. Remove EGR valve. Using vacuum pump, slowly apply vacuum on hose fitting at top of EGR valve while noting movement of poppet valve on EGR valve. If poppet valve moves with vacuum applied, EGR valve is operating properly. Go to next step. If poppet valve does not move with vacuum applied, replace EGR valve and recheck system operation.
6. Remove EGR tube. Check EGR tube and passages in intake manifold and exhaust manifold for restrictions caused by excessive carbon deposits. Clean EGR tube and passages as necessary. Also check base of EGR valve for excessive carbon deposits. DO NOT attempt to clean EGR valve. If excessive carbon deposits exist at base of EGR valve, replace EGR valve. Reinstall components and recheck system operation.
7. Shut engine off. Remove vacuum pump. Reinstall hose at top of EGR valve.

EGR Valve Leakage Test

1. If engine will not idle, idles rough, idles slow, or stalls, problem may be caused by exhaust gas leaking past poppet valve and seat in EGR valve when poppet valve is in closed position. To check for EGR valve leakage, note location of hoses on EGR valve and EGR backpressure transducer. Hose at top of EGR valve supplies vacuum to EGR valve. Hose on signal tube at bottom of EGR valve supplies exhaust pressure to EGR backpressure transducer.
2. With engine off, disconnect hose from top of EGR valve. Using vacuum pump, apply 15 in. Hg of vacuum on hose fitting at top of EGR valve and note vacuum reading. If vacuum holds steady at 15 in. Hg, go to next step. If vacuum does not hold steady at 15 in. Hg, replace EGR valve, as vacuum diaphragm is damaged. Go to next step.
3. Disconnect hose from signal tube at base of EGR valve. Remove air cleaner housing from throttle body. Apply approximately 50 psi (3.5 kg/cm 2 ) of compressed air on signal tube at base of EGR valve.
4. Open throttle valve on throttle body to full throttle position. Listen for air flowing from EGR valve into intake manifold. No air should be heard flowing from EGR valve into intake manifold.
5. If no air is flowing from EGR valve into intake manifold, poppet valve in EGR valve is operating properly. Remove vacuum pump and reconnect hose. If air is flowing from EGR valve into intake manifold, poppet valve in EGR is leaking. EGR valve must be replaced. Remove vacuum pump.

EGR Backpressure Transducer Test

1. Note location of hoses on EGR valve and EGR backpressure transducer. Hose at top of EGR valve supplies vacuum to EGR valve. Hose on signal tube at bottom of EGR valve supplies exhaust pressure to EGR backpressure transducer.
2. Disconnect hose from signal tube at base of EGR valve. Using vacuum pump, apply 10 in. Hg of vacuum on hose to bottom of EGR backpressure transducer and note vacuum reading. If vacuum holds steady at 10 in. Hg, go to next step. If vacuum does not hold steady at 10 in. Hg, replace EGR backpressure transducer, as vacuum diaphragm is damaged.
3. Disconnect vacuum supply hose from vacuum supply hose inlet on EGR solenoid. Install vacuum gauge on disconnected vacuum supply hose. Start engine and warm engine to normal operating temperature.
4. Accelerate engine to 1500 RPM and note vacuum reading. If full manifold vacuum exists, go to next step. If full manifold vacuum does not exist, check for defective or restricted vacuum supply hose to EGR solenoid.
5. Shut engine off. Remove vacuum gauge. Reinstall vacuum supply hose on vacuum supply hose inlet on EGR solenoid. Disconnect vacuum hose from vacuum hose outlet fitting on ERG solenoid. Install vacuum gauge on vacuum outlet fitting on EGR solenoid.
6. Disconnect electrical connector from EGR solenoid. This is done to simulate an open ground circuit from Powertrain Control Module (PCM) to the EGR solenoid. Start engine and warm engine to normal operating temperature. NOTE: For full manifold vacuum flow through EGR backpressure transducer, exhaust backpressure must be present at EGR backpressure transducer. Exhaust backpressure must be great enough to hold bleed valve in EGR backpressure transducer closed. It may be necessary to restrict exhaust gas flow from tailpipe so exhaust backpressure may be obtained. CAUTION: DO NOT cover tailpipe opening for an extended period, or system components may be damaged due to overheating.
7. Accelerate engine to 2000 RPM and note vacuum reading. With no exhaust backpressure, vacuum should be low. Have an assistant wearing heavy gloves, momentarily hold a rag over tailpipe opening to build exhaust backpressure while noting vacuum reading. Full manifold vacuum should exist as temporary exhaust backpressure is obtained.
8. Shut engine off. If full manifold vacuum exists, remove vacuum gauge and reconnect vacuum hose. If full manifold vacuum does not exist, replace EGR solenoid.

TEST 8

For EGR function testing, see appropriate ENGINE PERFORMANCE section of electronic information product.