Porsche 928 Workshop Manual page 605

Fuel Svstem. Electronic lnlection
Notes on idle speed and CO testing at idle
speed:
a) Idle speed
The 928 S4 is equipped with an adaptive idle-
speed cylinder filling control. This makes it un-
necessary to adjust the idle speed of any ver-
sion. On cars with adaptive idle-speed cylinder
filling control, system adaptation must only be
carried out after disconnecting the LH control
unit from thepermanent positive supply and
after each inspection.
Idle speed control value with engine at regular
operating temperature: GT 775 k 25/min
S4 675 + 25lmin
b) Idle speed CO value on cars without cata-
lytic converter
The CO level is still adjusted at the CO adjust-
ing screw on the potentiometer. The following
preconditions must be observed:
Engine at regular operating temperature
- Engine in good working order mechanically
and ignition system OK
- All electrical consumers switched off
- Exhaust emission tester at operating
temperature, calibrated and correctly ad-
justed.
D 24 - 28 LH-Diagnosis/Troubleshooting
a
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