NOTE: A vacuum pump capable of producing more than 10 in. Hg
(33.8 kPa) of vacuum will be needed to perform this test.
- Start the engine and warm it to full operating temperature. This can be
achieved quicker by driving the vehicle than by allowing it to idle.
- Disconnect the vacuum hose from the EGR valve and install a vacuum pump
and short piece of hose. Alternately, disconnect the EGR hose at the control
solenoid and connect the hose directly to the vacuum pump.
- With the engine running at warm idle, draw a vacuum with the hand pump;
the EGR valve should open. The engine sound should change, possibly even stalling,
depending on how far the valve is opened.
- Draw and release vacuum several times and at different speeds. The response
of the valve (and therefore the idle speed/quality) should be proportional
the the vacuum signal from the pump.
- Disconnect the test equipment and reconnect the vacuum hose.
