EGR Valve: Testing and Inspection

Vacuum Testing EGR Valve:

Check vacuum line conditions, Any hose or fitting found to be weak, collapsed or broken should be replaced with an approved vacuum hose.

Test integrity of EGR diaphragm using a hand held vacuum pump.
1. Using a hand vacuum pump, apply approx. 18"Hg (600 millibar) of vacuum to EGR valve.
2. If vacuum does not build up or drops in a short time by more than 2.95 in. of Hg (100 mbar), check vacuum pump connections for leaks or poor connections. If OK, replace EGR valve.
3. Relieve vacuum, start engine and let idle.
4. Momentarily apply vacuum to EGR valve.

NOTE: Do not apply vacuum for more than about 3 seconds or an emission control fault code will likely be stored in the computer memory. If this happens, the check engine light will come "ON" while the engine is still running. Turning the engine "OFF" and starting again may turn the light "OFF", but a fault code will still be in memory.

^ You should immediately observe a noticeable change in the way the engine runs.

If not, check for leaking EGR valve (exhaust leaking into intake through valve), or plugged valve or passage.

NOTE: A leaking valve may not affect the idle speed but will result in rough idle and incorrect idle stabilizer valve duty cycle. This may also set a fault code.