- Remove the EGR valve from the vehicle. Check for sticking of plunger caused
by excess carbon deposits. If such a condition exists, clean with appropriate
solvent so the valve seats correctly.
- Connect a vacuum pump to the valve and apply 20 in. Hg (67 kPa) of vacuum.
- Check for air tightness. If the valve has 2 vacuum ports; pick one and plug
the other. The vacuum must be retained.
- For 1990–94 vehicles, blow air from 1 passage of the EGR to check
condition as follows:
- With 1.8 in. Hg (6 kPa) of vacuum or less applied to the valve, air
should not pass through the valve.
- With 8.5 in. Hg (28.7 kPa) of vacuum or more applied to the valve, air
should pass through the valve.
| Fig. 1: Use a vacuum pump to test the EGR
|
- For 1995–98 vehicles, apply vacuum (specified below) and check the
passage of air by blowing through either side of the EGR passages, as follows:
- With 1.6 in. Hg or less of vacuum applied to the valve, air should blow
out of the opposite passage.
- With 8.7 in. Hg or more of vacuum applies to the valve, air should not
blow out of the opposite passage.
- If the results are not as described, replace the EGR valve.
- Disconnect the green striped vacuum hose from the throttle body, then connect
a hand-held vacuum pump to the vacuum hose.
- Plug the nipple from which the vacuum hose was disconnected.
- Under the engine conditions listed below, inspect the system operation by
applying vacuum from a hand held vacuum pump.
- With the engine temperature cold, 104°F (40°C) or below, the response
should be as follows:
- Engine at idle — vacuum should leak
- With the engine at temperature of 176°F (80°C) or higher, the
response should be as follows:
- With 1.8 in. Hg (6 kPa) of vacuum applied — the engine
should idle and vacuum should be maintained.
- With 8.5 in. Hg (29 kPa) of vacuum applied — the engine
should change from idling to slightly unstable and the vacuum should be
maintained.
- If the test results differ from those listed, thoroughly inspect the EGR
system components.
- Disconnect the green striped vacuum hose from the EGR valve and connect
a hand vacuum pump through a 3-way connector. The pump will now be installed
in the line.
- With engine cold (below 68°F), test system operation as follows:
- Race the engine by rapidly operating the accelerator.
- Measure the pressure reading on the pump. The negative pressure at the
valve should not change.
- With the engine warm (68°F or more), test system operation as follows:
- Race the engine by rapidly operating the accelerator.
- The negative pressure at the gauge rises to 3.9 in. Hg (13 kPa) or more.
- Disconnect the 3-way terminal and connect a hand vacuum pump to the EGR
valve.
| Fig. 2: Apply vacuum to the EGR valve to inspect
system operation
|
- When a negative pressure of 8.5 in. Hg (29 kPa) is applied during engine
idling, check that the engine stops or the idle becomes unstable.
- Inspect the system components if test results differ from specifications
listed above.
- Check the EGR control system and the valve with the engine fully warmed
up running. The engine coolant temperature should be over 170°F (76°C.)
- With the transaxle in Neutral, and the throttle close, let the engine idle
for about 70 seconds.
- Quickly accelerate the engine to about 2,000 rpm, but do not go over 3000
rpm.
- The EGR valve stem should move when accelerating the engine. Repeat the
test several times to confirm movement.
- If the EGR valve stem moves, the control system is operating normally.
- Disconnect and plug the vacuum hose from the EGR valve.
- Connect a vacuum pump to the EGR valve. Check to see if the engine stalls
or if the idle is unstable when a vacuum of 3.5 in. Hg (12 kPa) or higher
is applied while the engine is idling.
- Disconnect the vacuum hose (the 2.0L turbo has a green stripe and the 2.4L
engine has a white stripe), then connect a hand-held vacuum pump to the 3-way
terminal.
- Check the condition of the vacuum when the engine has been raced rapidly,
as follows:
- When the engine is cold, coolant temperature at 68°F (20°C)
or less, and the throttle is opened quickly, no vacuum should generate
(it should remain as barometric pressure).
- When the engine is hot, coolant temperature at 176°F (80°C)
or higher, and the throttle quickly opened, the vacuum should momentarily
rise over 3.9 in. Hg (13 kPa).
| Fig. 3: Location of the EGR solenoid and vacuum
hose — 2.0L turbo engine
|
| Fig. 4: EGR solenoid and vacuum line location — 2.4L
engine
|
- Disconnect the 3-way terminal.
- Connect the vacuum pump right to the EGR valve.
- Check to see if the engine stalls or if the idle is unstable when a vacuum
of 7.9 in. Hg or higher is applied while the engine is idling.
The EGR temperature sensor is used on California vehicles only. The EGR temperature
sensor detects the temperature of the gas passing through the EGR control valve.
It converts the detected temperature into an electrical voltage signal which
is sent the vehicles Engine Control Unit (ECU). If the circuit of the EGR temperature
sensor is broken, the warning light will come on.
- Remove the EGR temperature sensor from the engine.
| Fig. 5: Put the EGR temperature sensor in a container
of water, then measure resistance as the water temperature is increased
|
- Place the EGR sensor into water. While increasing the temperature of the
water, measure the sensor resistance. Compare the values to following specifications:
- 122°F (50°C) — 60–83 k.ohms resistance
- 212°F (100°C) — 11–14 k.ohms resistance
- If the resistance obtained varies significantly from specifications, replace
the sensor.
- Label and disconnect the vacuum hose at the thermo valve.
- Connect a hand held vacuum pump to the vacuum hose on the thermo valve.
| Fig. 6: Testing the thermal vacuum valve — 2.0L
engine (Federal) shown, others similar
|
- Apply vacuum and check the air passage through the thermo valve. Compare
results to the following specifications:
- Engine coolant temperature of 122°F (50°C) or less — vacuum
leaks
- Engine coolant temperature of 176°F (80°C) or more — vacuum
is maintained
- If the results differ from the desired specifications, replace the valve.
- Disconnect the vacuum hose from the throttle body EGR vacuum nipple. Connect
a hand-held vacuum pump to the nipple.
| Fig. 7: Connect a vacuum pump to the EGR vacuum nipple
on the throttle body — 1995–98 2.0L non-turbo
engine shown
|
| Fig. 8: Location of the throttle body EGR valve vacuum
nipple — 2.4L engine shown
|
- Start the engine, then slowly raise the speed and compare with the following
specifications.
- For 1990–94 vehicles, check to be sure the vacuum raised proportionally
with the rise in engine speed.
- For 1995–98 vehicles, the vacuum reading on the pump should remain
constant.
- Label and disconnect the yellow and green striped vacuum hose from the EGR
solenoid.
- Disconnect the electrical harness connector.
- Connect a hand vacuum pump to the nipple to which the green-striped vacuum
hose was connected.
- Apply a vacuum and check for air-tightness when voltage is applied and discontinued.
When voltage is applied, the vacuum should be maintained. When voltage is
discontinued, vacuum should leak.
| Fig. 9: Apply voltage to the EGR solenoid using jumper
wires and check for air-tightness using a vacuum pump
|
| Fig. 10: Measure the resistance between the terminals
of the EGR solenoid
|
- Measure the resistance between the terminals of the solenoid valve. The
resistance should be 36–44 ohms at 68°F (20°C).
- If the test results differ from the specifications, replace the EGR solenoid.
NOTE: On these engines, the solenoid is referred to as an electric
EGR transducer solenoid.
- Disconnect the vacuum hose from the electric EGR transducer.
- Detach the harness connector.
- Plug nipple A, then connect a hand vacuum pump to nipple B.
- Use a jumper wire to connect the solenoid terminal to the battery terminal.
- Turn on and off the negative battery terminal side under wire and apply
vacuum and positive pressure to check the air tightness. Compare with the
following specifications:
| Fig. 11: Electric EGR transducer solenoid test connections — 1995–98
2.0L non-turbo engine
|
- With the jumper wire disconnected and pressure not applied, vacuum should
leak.
- With the jumper wire disconnected and pressure applied, the vacuum should
be maintained.
- With the jumper wire connected and pressure not applied, vacuum should
be maintained.
- Measure the resistance between the terminals of the solenoid. The resistance
should be 25–35 ohms at 68°F (20°C).
- If the test results differ from the specifications, replace the solenoid.
NOTE: Before disconnecting the vacuum hoses, tag them to assure
proper connection during installation
- Tag and disconnect the vacuum hose (2.0L turbo engine: yellow stripe, white
and green stripe, 2.4L engine: yellow stripe and white stripe) from the solenoid
valve.
- Detach the harness connector.
- Connect a hand-held vacuum pump to the nipple to which the white stripe
vacuum hose was connected (2.0L turbo) or the A nipple (2.4L).
- Check air tightness by applying a vacuum with voltage applied directly from
the battery to the EGR control solenoid valve and without applying voltage.
| Fig. 12: Checking the EGR solenoid — 2.0L
turbo engine
|
| Fig. 13: EGR solenoid check connections — 2.4L
engine
|
- For 2.0L turbo engines, compare with the following:
- With battery voltage not applied and the B nipple open, vacuum should
be maintained.
- With battery voltage applied and the B nipple open, vacuum should leak.
- With battery voltage applied and the B nipple closed, vacuum should
be maintained.
- For the 2.4L engines, compare with the following:
- With battery voltage not applied, vacuum should be maintained.
- With battery voltage applied, vacuum should leak.
- Using an ohmmeter, measure the resistance between the solenoid valve terminals.
The resistance should fall between 36–44 ohms when the engine temperature
is 68°F (20°C).
