When EGR valve is open?
The EGR valve is closed when the engine is starting up. During idle and at low speeds, only a small amount of power is required, and therefore only a small amount of oxygen, so the valve gradually opens – it can be up to 90% open at idle.
What is the voltage of an EGR valve?
With the valve closed a voltage of 0.7 Volts was present on the signal wire and with the valve fully open a voltage of 3.5 Volts was present on the signal wire. This proved the EGR valve was working as expected. The next step in the diagnosis was to actuate the EGR valve while monitoring the output from the MAP sensor.
Why does the EGR valve open when the engine is warm?
Because the engine is warm, the ECU applies a negative voltage to the DC motor which makes the EGR valve open, which is visible in the slight drop of the position sensor signal voltage.
How to test an EGR valve with a hand mirror?
As you do this, watch the valve diaphragm movement. Use a small hand mirror for this, if necessary. If the stem or diaphragm doesn’t move, disconnect the thin vacuum hose from the top of the valve. Place your finger on the opening of the vacuum hose you just disconnected. Increase engine rpm again as you did in the previous step.
Can a multimeter be used to test EGR?
The vehicle computer operates the valve instead of previous years EGR valves, which are operated by the engine vacuum. The procedure to test an electronic EGR is a bit different and requires a multimeter. If you notice your vehicle running poorly, stalling or having poor gas mileage, you should test the EGR.
What causes the EGR valve to open more than required?
If there is an issue with the voltage, the ECM may open the EGR valve more than required, causing the engine to hesitate or the acceleration to drop. If the ECM does not receive correct information from the EGR position sensor, the EGR valve position will not be determined correctly, resulting in rough engine performance.
How does the ECU adjust the EGR valve?
The ECU does this by applying a positive voltage to the DC motor to assist the spring with closing the EGR valve. When the throttle is released, the EGR valve is slightly opened again and the opening is further adjusted when the engine is back to idle speed again. Signal values may differ on different types of engine control units and EGR valves.
What should dpfe voltage be for EGR valve?
Assuming the EGR valve is ok the engine should begin to stumble and possibly even stall as vacuum is applied to the valve and the pintle opens. Your DPFE voltage should also approach 4.5 volts.
Where is the EGR valve DC motor located?
The EGR valve is situated between the exhaust and inlet. The EGR valve that is measured is equipped with a DC motor to control the valve and an EGR valve position sensor to give feedback to the ECU about the position of the EGR valve. The EGR valve is spring loaded to keep it closed.