EGR Backpressure Transducer: Testing and Inspection

SYSTEM DESCRIPTION
The EGRC-BPT valve monitors exhaust pressure to activate the diaphragm, controlling throttle body vacuum applied to the EGR valve. In other words, recirculated exhaust gas is controlled in response to positioning of the EGR valve or to engine operation.

ON-BOARD DIAGNOSIS LOGIC
If too much EGR flow exists due to an EGRC-BPT valve malfunction, off idle engine roughness will increase. If the roughness is large, then the vacuum to the EGR valve is interrupted through the EGR valve & EVAP canister purge control solenoid valve. If the engine roughness is reduced at that time, the EGRC-BPT valve malfunction is indicated.




DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE




OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the EGRC-BPT valve. During this check, a DTC might not be confirmed.
1. Disconnect the rubber tube to the fuel pressure regulator at the intake manifold.
2. Disconnect the rubber tube to the EGR valve & EVAP canister purge control solenoid valve at the EGRC-BPT valve.
Connect the intake manifold and the EGRC-BPT valve with a rubber tube that has 1 mm (0.04 in) dia. orifice installed. (The intake manifold vacuum will be directly applied to the EGRC-BPT valve.)
3. Start engine.
4. Check for the EGR valve lifting with engine at less than 1,500 rpm under no load.
EGR valve should remain closed.
5. Check the EGR valve lifting when revving from 2,000 rpm up to 4,000 rpm under no load. EGR valve should lift up, and go down without sticking when the engine is returned to idle.
6. Check rubber tube between EGR valve & EVAP canister purge control solenoid valve and throttle body for improper connection, cracks or blockages.




COMPONENT INSPECTION
1. Plug one of two ports of EGRC-BPT valve.
2. Vacuum from the other port and check leakage without applying any pressure from under EGR-BPT valve. Leakage should exist.