CHECKING FUNCTION FO EGR SYSTEM
a) BMW 630 CSi

A) Air Pump
Detach hose (1).
Star engine.
Air pump is good, if air stream velocity increases
with an increasing engine speed.
Air Stream Velocity Does Not Increase:
1. Check belt tightness.
2. Check air pump for easy movement and correct installation.

B) Blowoff Coasting Valve
Blow off coasting valve prevent
1. backfiring in exhaust when releasing accelerator and
2. overloads on air pump.
Check hoses for cracks, bends and correct routing.
Pull off white hose (1) from blowoff coasting
valve with engine running and coolant temperature
below +45°C (113°F).
Vacuum must be noticed.
Attach hose (1) again.
No air should escape from blowoff coastind
valve while engine is running at idle.
Open throttle by hand briefly and close again.
Air should escape through opening on blowoff
coasting valve for 1 to 3 seconds.
No Air:
Blowoff coasting valve is defective.

C) Check Valve
Check valves will prevent recirculation of exhaust
gases from reactors.
Check valve is defective, if hoses have definite
traces of exhaust gas.
Detach hose (1) from blowoff coasting valve
and blow in air in direction on reactors.
Air must only flow through in direction of reactors.
When taking in air, valve must be closed.

D) EGR Valve
Engine must run at idle speed and have operating
temperature for all tests.
1. Pull off blue hose (1) from EGR valve.
Do not plug connection or hose.
Engine speed must not change.
Engine Speed Drops:
EGR valve is defective.
Idle position of throttle is maladjusted.
Check red hose from throttle housing for
vacuum.

2. Pull off blue hose (1) from EGR valve.
Pull off white hose from collector.
Pull off red hose (2) from throttle housing
and attach at connection (3).
Engine speed should drop considerably.
Engine Speed Does Not Drop:
EGR valve is defective.
Water temperature switch (45°C/113°F) or
relay is defective.
Red electric switching valve is defective.

E) Pressure Converter
Engine must run at idle speed and have operating
temperature for all tests.
1. Exhaust Backpressure/Control Pressure
Pull off red hose (1) from pressure converter.
Backpressure should be felt with finger.
No Backpressure:
Backpressure line and/or hose are defective
or plugged.

2. Intake Vacuum
Pull off white hose (2) from pressure converter
and feel vacuum with finger.
No Vacuum:
Check vacuum hose for leaks.

3. Governor Pressure
Pull off red hose (1) and blue hose (3).
Vacuum must be felt with finger at blue
pressure converter connection.
No Vacuum:
Replace pressure converter.

F) Red Electric Switching Valve (1)
Switching valve (1) must switch off EGR valve at
a coolant temperature below +45°C (113°F)
and an engine speed above 3750 rpm.
Control is by way of water temperature switch (2),
switching relay (3) and speed switch (4).
With engine stopped and coolant temperature below
45°C (113°F), pull off red hose from EGR
valve and blow in air.
Switching valve (1) is okay, if there is no air flow
with ignition off and air flow with ignition on.

G) Water Temperature Switch (2) and Switching
Relay (3)
Coolant temperature below 45°C (113°F).
Turn on ignition with engine stopped.
Pull off plugs on switching valve (!) and connect
test lamp to both terminals.
Test lamp should come on.
Test Lamp Not On:
Water temperature switch is defective.
Switching relay is defective.
Ground wire has a break.

H) Water Temperature Switch (2), Switching
Relay (3) and Speed Switch (4)
Coolant temperature above 45°C (113°F).
Turn on ignition with engine stopped.
Pull off plugs from red switching valve (1) and
connect a test lamp to both terminals.
Test lamp must not be on.
Test Lamp On:
Water temperature switch is defective.
Switching relay is defective.
Speed switch is defective.

I) Speed Switch (4)
Run engine at idle speed.
Pull off plugs on blue switching valve (5) and
connect a test lamp to both terminals.
Test lamp must not be on.
Test Lamp On:
Speed switch is defective.
Increase engine speed.
As from approx. 3750 rpm test lamp should be on.
Test Lamp Not On:
Speed switch is defective.
Ground wire has a break.

J) White Electric Switching Valve (6)
White switching valve (6) controls the blow-off
coasting valve.
Switching valve must be open at a coolant temperature
below 45°C (113°F) and closed above 45°C (113°F).
Test with engine stopped and coolant temperature
above 45°C (113°F).
Pull off white hose from blowoff coasting valve
and blow in air.
Switching valve (6) is okay, if there is air flow
with ignition on and no air flow with ignition off.

Test with engine stopped and ignition on.
Pull off plugs from white switching valve (6) and
connect a test lamp to both terminals.
Test lamp should be on at coolant temperature
above 45°C (113°F).
Test Lamp Not On:
Temperature switch (2) is defective.
Switching valve (3) is defective.
Ground wire has a break.

CHECKING FUNCTION OF EGR SYSTEM
b) BMW 633 CSi

BMW 633 CSi

BMW 633 CSi

A) Air Pump
Detach hose (1).
Start engine.
Air pump is good, if air stream velocity increases
with an increasing engine speed.
Air Stream Velocity Does Not Increase:
1. Check belt tightness.
2. Check air pump for easy movement and
correct installation.

B) Booster Blowoff Valve
Booster blowoff valve prevents
1. backfiring in exhaust when releasing accelerator and
2. overloads on air pump.
Check hoses for tears, pinches and correct routing.
Pull off white hose (1) from booster blowoff valve.
Vacuum must be noticed with engine running (idling).
Reconnect hose (1).
At idle speed no air should escape from booster
blowoff valve.
Open throttle by hand briefly and close again.
Air must escape from booster blowoff valve 1
to 3 seconds when opening throttle.
No Air:
Booster blowoff valve is defective.

C) Check Valve
Check valve should prevent a backflow of exhaust
gas from the reactor.
Check valve is defective, if hoses show definite
traces of exhaust gas.
Detach hose (1) from booster blowoff valve and
blow in air in direction of reactor.
Air must only pass through in direction of reactor.
Valve must be closed when taking in air.

D) EGR Valve
All tests require engine to be running and at operating temperature.
1. Pull off blue hose (1) from EGR valve.
Do not plug connection or hose.
Engine speed should not change.
Engine Speed Drops:
EGR valve is defective.
Idle position of throttle is maladjusted.
Check red hose from throttle housing for vacuum.

2. Pull off blue hose (1) from EGR valve.
Pull off white hose from collector.
Pull off red hose (2) from throttle housing
and attach at connection (3).
Engine speed should drop considerably.
Engine Speed Does Not Drop:
EGR valve is defective.
Water temperature switch (45°C/113°F) or
relay is defective.
Red electric switching valve is defective.

E) Pressure Converter
Engine must run at idle speed and have operating
temperature for all tests.
1. Exhaust Backpressure/Control Pressure
Pull off red hose (1) from pressure converter.
Backpressure should be felt on finger.
No Backpressure:
Backpressure line and/or hose are defective
or plugged.

2. Intake Vacuum
Pull off white hose (2) from pressure converter
and feel vacuum with finger.
No Vacuum:
Check vacuum hose for leaks.

3. Governor Pressure
Pull off red hose (1) and blue hose (3).
Vacuum must be felt with finger at blue
pressure converter connection.
No Vacuum:
Replace pressure converter.

F) Red Electric Switching Valve (1)
Switching valve (1) must switch off EGR valve at
coolant temperature below 45°C (113°F) and
an engine speed above 3750 rpm.
Control is by way of coolant temperature switch
(2) and speed switch (3).
With engine stopped and coolant temperature
above 45°C (113°F), pull off red hose from EGR
valve and blow in air.
Switching valve (1) is okay, if air passes through
with ignition off or there is no air flow with the
ignition on.

G) Coolant Temperature Switch (2)
Coolant temperature below + 45°C (113°F).
Turn on ignition with engine stopped.
Pull off plugs on switching valve (1) - red - and
connect test lamp between both poles.
Temperature switch (2) is okay, if test lamp does
not come on at coolant temperature below 45°C
(113°F).
Test Lamp On:
Coolant temperature switch is defective.
Speed switch is defective.
EGR relay is defective.

H) Coolant Temperature Switch (2) and Speed
Switch (3)
Coolant temperature above 45°C (113°F).
Turn on ignition with engine stopped.
Pull off plugs on red switching valve (1) and
connect test lamp between both poles.
Test lamp should be on.
Test Lamp Not On:
Coolant temperature switch is defective.
Speed switch is defective.
EGR relay is defective.

I) Speed Switch (3)
Run engine at idle speed.
Pull off plugs on blue switching valve (4) and
connect test lamp between both poles.
Test lamp should not come on.
Test Lamp On:
Speed switch is defective.
Increase engine speed.
Test lamp should come on above approx. 3750 rpm.
Ground test lamp.
If test lamp comes on now, power line has no
ground connection.
Test lamp still not on, speed switch is defective.

J) Black Electirc Switching Valve (5)
Only for California and 49 State High Altitude
Version (Manual Transmission)
Stop engine and turn on ignition.
Pull off plugs on black switching valve (5) and
connect test lamp between both poles.
Test lamp should be on when engaging 4th gear.
Test Lamp Not On:
Switch on transmissiong is defective.
Plug connectors not connected.