Porsche 928 Workshop Manual page 594

928 S4
928
GT
Electronic
Fuel Injection
24
Fault, Fault Code Possible Causes, Elimination, Remarks
Checking the control signal
Insert 2-pin DME test lead (Bosch No.
1 664 463
093) between rotary
actuator and plug connection.
Connect engine tester as stated in manufacturer's instructions, and
adjust.
Make sure that there is no contact between the lead connectinos and
ground on the vehicle (risk of short circuit).
With the engine running, the following display must be seen:
Test point 7
Oxygen regulation
0
Control (rich)
Fault code l-23
-
- -
-
-
-
-
-
-
Frequency approx. 100 Hz.
If there is no audible pulse in spite of the power supply and the sig-
nal being present, renew the idle speed control.
Mixture preparation problems are preventing the oxygen regulator
from operating within its control range. It therefore moves back to its
stop.
Test 1: With the engine running and a CO tester connected,
note the CO content (between 0.4-l .2 %)
Too lean: check intake system (test point 19)
LH-Diagnosis/Troubleshooting
Prlnted In Germany - Xxv, 1990
D24-17