P0402

EGRC-BPT Valve Function P0402

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 excess EGR flow exists due to an EGRC-BPT valve malfunction, engine roughness will be increased. If the roughness is large, then the vacuum to the EGR valve is interrupted through the EGRC-solenoid valve. If the engine roughness is reduced at that time, the EGRC-BPT valve malfunction is indicated.






OVERALL FUNCTION CHECK
Instead of performing DTC DETECTING CONDITION, the following method can be used for checking the EGRC-BT valve function. (The "NG" of the OVERALL FUNCTION CHECK means the same as the DTC detection.)






1. Disconnect the rubber tube to the fuel pressure regulator at the intake manifold.
2. Disconnect the rubber tube to the EGRC-BPT valve, which comes from the EGR and canister control solenoid.
Connect the intake manifold and the EGRC-BPT valve with a rubber tube. (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 and not lift up.

5. Check the EGR valve lifting when revving from 2,000 rpm up to 3,500 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 EGRC-solenoid valve and throttle body for improper connection, cracks or blockages.

COMPONENT INSPECTION
EGRC-BPT valve






(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.