0010 - Function of the injection system M. Pneumatic idle-speed increase (PLA) (note deviations for off-road vehicles) Engines 601, 602.91, 603.91 · ra0701601m010x · Mercedes-Benz WIS

07.1-010 Function injection system

M. Pneumatic idle speed increase (PLA)

1st version (with 2 thermovalves)
Idle speed is increased for speed stabilization up to approx. 17 °C coolant temperature and on vehicles with automatic transmission when switching on the AC compressor even above approx. 17 °C coolant temperature.

The vacuum unit (4) attached to the governor housing is activated via the thermovalves (128 and 130) and the change-over valve (Y12). If vacuum (approx. 500 mbar) is available at the vacuum unit (4), the idle speed spring is pulled via the pushrod (4b) of the vacuum unit. The idle speed characteristic is shifted and the idle speed increased by approx. 100/min.

Coolant temperature < approx. 17 °C
The thermovalve (128) is open, the thermovalve (130) is closed. On vehicles with automatic transmission and air conditioner the vacuum reaches the vacuum unit (4) via the change-over valve (Y12) and on vehicles with manual transmission directly.

Coolant temperature > approx. 17 °C
The thermovalve (128) is closed, the thermovalve (130) is open. The vacuum unit is ventilated and the speed increase cancelled.

When switching on the AC compressor (only vehicles with automatic transmission), the change-over valve is supplied with voltage and switches. The vacuum reaches the vacuum unit (4) via the upper connection of the change-over valve.

2nd version (with 1 thermovalve)
Vehicles with manual transmission
Coolant temperature < 30 °C
The thermovalve (128a) is open. The vacuum of approx. 700 mbar reaches the vacuum unit idle speed increase (4) via the thermovalve (128a). The idle speed is increased by approx. 100/min. The choke in the ventilation filter (62a) causes a pressure loss of approx. 100 mbar.

Coolant temperature > 30 °C
The thermovalve (128a) is closed. Atmospheric pressure reaches the vacuum unit (4) through the choke in the ventilation filter (62a). The speed increase is cancelled.

1st version

Arrangement of choke with

filter (62a) 0.3 mm orifice diameter

2nd version

Arrangement of choke with

filter (62b) 0.13 mm orifice diameter

1st version engine 601 in model 201
Function diagram idle speed increase with manual transmission
Standard version and  Federal as of 1984

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
e	Brake booster
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ws	white

1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
62	Ventilation filter
67	Vacuum pump
128	Thermovalve closes at approx. 17 °C
130	Thermovalve opens at approx. 17 °C
140	Check valve brake booster

1st version engine 601 in model 201
Function diagram idle speed increase with automatic transmission
Standard version as of 1984

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
d	Vacuum unit automatic transmission
e	Brake booster
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ws	white

1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
61a	Choke (blue)
62	Ventilation filter
65	Vacuum control valve
67	Vacuum pump
72	Damper
128	Thermovalve closes at approx. 17 °C
130	Thermovalve opens at approx. 17 °C
140	Check valve brake booster

1st version engine 601 in model 201
Function diagram idle speed increase with automatic transmission
Standard version with air conditioner 1984, and  Federal

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
d	Vacuum unit automatic transmission
e	Brake booster
g	To AC compressor
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ws	white

Y12	Change-over valve speed increase
1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
61a	Choke (blue)
61b	Choke 0.5 mm orifice diameter orange
62	Ventilation filter
65	Vacuum control valve
67	Vacuum pump
72	Damper
128	Thermovalve closes at approx. 17 °C
130	Thermovalve opens at approx. 17 °C
140	Check valve brake booster

1st version engine 601 in model 201
Function diagram idle speed increase with manual transmission
 California as of 1984

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
e	Brake booster
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ge	yellow

Y27	Change-over valve electrical for EGR valve
Y28	Change-over valve electrical for vacuum control flap
1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
60	EGR valve
61b	Choke 0.5 mm orifice diameter orange
62	Ventilation filter
65	Vacuum control valve
67	Vacuum pump
72	Damper
99	Vacuum control flap
100	Vacuum unit for vacuum control flap
105	Intake pipe
110	Exhaust manifold
120	Exhaust gas recirculation line
123	Vacuum transducer
124	Adjusting screw for vacuum transducer
128	Thermovalve closes at approx. 17 °C
130	Thermovalve opens at approx. 17 °C
140	Check valve brake booster

1st version engine 601 in model 201
Function diagram idle speed increase with automatic transmission
 California as of 1984

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
d	Vacuum unit automatic transmission
e	Brake booster
f	To AC compressor control unit
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ge	yellow

Y12	Change-over valve electrical for speed increase
Y27	Change-over valve electrical for EGR valve
Y28	Change-over valve electrical for vacuum control flap
1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
60	EGR valve
61a	Choke
61b	Choke 0.5 mm orifice diameter orange
62	Ventilation filter
65	Vacuum control valve
67	Vacuum pump
72	Damper
99	Vacuum control flap
100	Vacuum unit for vacuum control flap
105	Intake pipe
110	Exhaust manifold
120	Exhaust gas recirculation line
123	Vacuum transducer
124	Adjusting screw for vacuum transducer
128	Thermovalve closes at approx. 17 °C
130	Thermovalve opens at approx. 17 °C
140	Check valve brake booster

2nd version engines 601 and 602 in models 124 and 201
Function diagram idle speed increase with manual transmission as of 1985

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
e	Brake booster
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ws	white

1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
61b	Choke 0.5 mm orifice diameter orange
62	Ventilation filter
62a	Ventilation filter with choke 0.3 mm orifice diameter
67	Vacuum pump
128a	Thermovalve closes at approx. 30 °C (aluminum, yellow)

2nd version engines 601 and 602 in models 124 and 201
Function diagram idle speed increase with automatic transmission as of 1985

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
d	Vacuum unit automatic transmission
e	Brake booster
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red

1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
61a	Choke (blue)
61b	Choke 0.5 mm orifice diameter orange
62	Ventilation filter
65	Vacuum control valve
67	Vacuum pump
72	Damper
128	Thermovalve closes at approx. 17 °C
130	Thermovalve opens at approx. 17 °C

3rd version
Engines 601 and 602 in models 124 and 201
Instead of the two 17° thermovalves, a thermovalve with 30 °C is installed now in order to standardize vehicles with automatic transmission. The ventilation filter (62b) is changed throughout. It is now equipped with a choke orifice diameter of 0.13 (previously
0.3 mm diameter).

Function diagram idle speed increase manual and automatic transmissions

a	Ventilation line to vehicle interior
b	Key shut-off
c	Remaining users
sw	black
bl	blue
br	brown
gr	green
vi	purple
rt	red
ws	white

1	Injection pump
2	Governor
4	Vacuum unit idle speed increase
5	ADA unit
6	Vacuum unit (stop)
61b	Choke 0.5 mm orifice diameter orange
61e	Choke orifice diameter 0.8 mm
62	Filter
62b	Ventilation filter with choke orifice diameter 0.13 mm
67	Vacuum pump
128a	Thermovalve closes at approx. 30 °C (aluminum, green)

0010 - Function of the injection system M. Pneumatic idle-speed increase (PLA) (note deviations for off-road vehicles) Engines 601, 602.91, 603.91

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