Porsche 1989 944 S2, Workshop Manual

Page: 156 / 167

24/28
Fuel System - Electronic Control 944 S/944 S2
Test Point 19: Intake System leaks
Check all connections after the air flow
sensor for leaks. Remove upper air cleaner
section. Apply Special Tool 9264/4 on the air
flow sensor and produce approx. 0.5 bar
pressure in the intake system. Leaks will
cause the pressure in the system to drop
quickly.
(944 S: shut the safety pressure valve for
crankcase breathing.)
Remarks:
Flashing Fault Code 1_23 (oxygen
regulation on stop) is displayed in cars with
oxygen regulation and very large leakage in
the intake system (for example: intake pipe
gasket).
Test Point 20: Ground Connections (V)
Ground read (2 x) from wire harness to
engine block.
battery ground lead on clutch bell
housing (engine ground) and on body
(body ground next to battery).
Ignition final stage ground on side
member at left front.
Fuel pump ground on rear lock cross
wall behind the spare wheel.
Are ground connections tight and without
corrosion? Loosen, clean and retighten
ground connections as specified.
Caution!
Never start the engine as long as the
ground lead between the body and
engine is disconnected!
This would destroy the control unit
immediately!.
D 24/28 - 22 DME - Diagnosing/Troubleshooting
Printed In Germany - XXI, 1989