Rough Idle? Check for stored diagnostic codes.
The CIS injection control unit stores malfunctions in the system. Several discussions on this website describe how to retrieve the codes. They are taken from pin 3 of the diagnostic connector. The interpretation of the codes are as follows:
1 No faults in system.
2 Throttle valve switch (full throttle contact).
3 Coolant temp sensor.
4 Airflow sensor potentiometer.
5 Oxygen sensor.
7 TNA (RPM) signal.
8 Altitude pressure signal from EZL Ignition control unit.
9 Current to Electro-hydraulic actuator.
10 Throttle valve switch (idle contact).
11 Air injection system.
12 Absolute pressure valves from ELZ ignition control unit.
13 Intake air temp signal.
14 Road speed signal at CIS-E control unit.
16 EGR (Y27)
17 Oxygen sensor signal.
18 Current to idle speed air valve.
22 Oxygen sensor heating voltage implausible.
23 Short to positive in purge switchover switch over valve circuit (Y58/1).
25 Short to positive in start valve circuit (Y8).
26 Short to positive in shift point retard circuit (Y3/2).
27 Data exchange fault between CIS-E control unit and EZL ignition control unit.
28 Loose contact in coolant temp sensor circuit (B3/2).
29 Difference in coolant temps between CIS-Eunit and EZL unit.
31 Loose contact in intake air temp sensor circuit (B17/2).
34 Faulty coolant temp sensor signal from EZL unit.