General information
In order to reduce the emission of nitrogen oxides into the atmosphere, part of the exhaust gases are returned to the intake manifold through the EGR valve. Such mixing of exhaust gases into the air-fuel mixture leads to a decrease in its combustion temperature.
The system consists of an EGR valve, an EGR control solenoid valve (used only on some models), eGR valve opening sensor and control module (ECM/PCM). The ECM/PCM is programmed to provide the optimum degree of opening of the EGR valve for all engine operating conditions. A special information sensor constantly monitors the degree of opening of the EGR valve, sending appropriate signals to the control module. The ECM/PCM compares the incoming information with data from other sensors and, if necessary, adjusts the depth of vacuum supplied to the EGR valve via the electromagnetic control valve.
Examination
Models equipped with CVT
1. Start the engine and warm it up to normal operating temperature (the cooling system fan should turn on).
2. Disconnect the vacuum hose from the EGR valve and connect a vacuum gauge to it.
3. There should be no vacuum, if this condition is met, proceed to the procedures in paragraph 5.
4. If vacuum is present, disconnect the EGR control solenoid valve connector and recheck for vacuum at the EGR valve.
Note: To locate the solenoid valve, follow the vacuum hose from the EGR valve. If there is no vacuum, take the vehicle to a service station to have the ECM/PCM diagnosed using a special reader (see Checking the condition and replacing the TDC/crankshaft position/piston position sensor in the engine cylinders (TDC/CKR/CYP)). If there is a vacuum, check that the vacuum lines are properly routed. If the hoses are OK, replace the solenoid valve.
5. If there was no vacuum from the start, connect a hand vacuum pump to the EGR valve and create a vacuum of 203 mm Hg - the engine should stall. Also check the ability of the valve to hold the vacuum, if there is no such ability, replace the assembly.
6. Check for battery voltage at the EGR control solenoid valve. Disconnect the 2-pin valve connector and connect a voltmeter between the positive terminal of the main harness connector (red wire terminal) and ground. Battery voltage must be present.
7. Connect a vacuum gauge to the EGR valve vacuum hose and run the engine at idle. Using a jumper wire, connect the positive battery terminal to the red wire terminal on the back of the harness side of the connector. While observing the vacuum gauge reading, ground the other terminal of the 2-pin connector using a second jumper wire. The vacuum should increase within one second (the sound of the solenoid valve operating should be heard). If there is no vacuum, replace the EGR solenoid valve assembly.
8. More detailed diagnostics of the system requires the use of a special reader and should be performed in a car service workshop.
Models with manual transmission
1. Start the engine and warm it up to normal operating temperature (the cooling system fan should work).
2. Disconnect the 6-pin EGR valve connector and check for battery voltage between the pink and black wire terminals of the main wiring harness. If there is no voltage, check the pink wire between the valve and the ECM/PCM for any signs of open or loose connections. Also check for a secure ground on the black wire. If the wiring is OK, the vehicle should be taken to a service station for a detailed diagnosis of the ECM/PCM.
3. If battery voltage is present, stop the engine. Using a jumper wire, connect the positive battery terminal to the pink wire terminal of the 6-pin EGR valve/EGR sensor wiring connector. Run the engine at idle and use a second jumper wire to ground the black wire terminal of the connector. The idle speed should suddenly become unstable until the engine stops, otherwise replace the valve/sensor assembly. If there is no change in engine performance, check the wiring for an open circuit and check the tightness of the contact connections.
4. More detailed diagnostics of the system requires the use of a special reader and should be performed in a car service workshop.
Replacement of components
EGR valve
1. Disconnect the wiring from the EGR valve opening sensor. Disconnect the vacuum hose.
2. Loosen the two mounting nuts and remove the EGR valve from the intake manifold.
3. Clean the mating surfaces of the valve and its adapter.
4. Replace the sealing gasket and install the EGR valve in its original place. Tighten the mounting nuts securely.
5. Restore the original electrical wiring connection.
EGR control solenoid valve (only models with CVT)
1. Follow the vacuum hose from the EGR valve to locate the EGR solenoid valve. Disconnect the wiring and vacuum hoses, remove the mounting screws and remove the valve.
2. Installation is carried out in reverse order.
[The article was taken from the website: www.HondaBook.ru]