Cylinder Balance Test
- This test helps identify a weak or non-contributing cylinder in engines with SFI fuel systems. PCM shuts off fuel supply to each injector and measures RPM drop. It computes variation between cylinders and identifies weak ones. Total test time is about 3 minutes.
- This test mode is entered from KOER SELF-TEST after all codes have been displayed. Within 2 minutes after codes have been displayed, apply and release throttle). After a brief stabilizing period, PCM will activate test procedure.
- If Code 90 is displayed during this test, system has passed test. If Code 77 is displayed, repeat cylinder balance test. If throttle is moved during this test, Code 77 will appear, indicating test is not completed. If a weak cylinder is indicated, repeat test. See CYLINDER BALANCE TEST SERVICE CODES table below.
- Test will be repeated if throttle is applied and released within 2 minutes of final code output. When repeating test sequence, percentage of allowable variation between cylinders is reduced. If Code 90 is displayed, cylinder identified in previous first test is considered weak. If code 90 cannot be obtained, cylinder is considered non-contributing.
CYLINDER BALANCE TEST SERVICE CODES
| Service Code |
Application |
| 90 |
Pass |
| 10 |
Cylinder No. 1 |
| 20 |
Cylinder No. 2 |
| 30 |
Cylinder No. 3 |
| 40 |
Cylinder No. 4 |
| 50 |
Cylinder No. 5 |
| 60 |
Cylinder No. 6 |
| 77 |
Retest |
| 538 |
Retest |
EEC-IV DIAGNOSIS BY SYMPTOM
| Symptom |
Application |
Circuit Test |
| A/C Does Not Cut Off During WOT |
Ranger |
KM - Step 15) |
| A/C Not Functioning |
Ranger |
KM - Step 1) |
| Black Exhaust Smoke |
Ranger |
H - Step 1) |
| CHECK ENGINE Light Always On |
Ranger |
ML - Step 1) |
| CHECK ENGINE Light Flashing With Erratic Idle |
Ranger |
ML - Step 15) |
| CHECK ENGINE Light Never On |
Ranger |
ML - Step 4) |
| CHECK ENGINE Light On Intermittently |
Ranger |
ML - Step 10) |
| Difficult Start |
Ranger 2.3L |
NB - Step 25) |
| Engine Hesitates After Hot Restart |
Ranger |
H - Step 21) |
| Engine Hesitation |
Ranger |
S - Step 2) |
| Engine Lacks Power or Loses Power |
Ranger |
S - Step 2) |
| Engine Miss At Idle, Acceleration Or Cruise |
Ranger |
S - Step 2) |
| Engine Runs Rough At All Times |
Ranger |
S - Step 2) |
| Engine Stalls |
Ranger |
S - Step 2) |
| Engine Stalls During Trans. Downshift |
Models With A/T |
TC - Step 1) |
| Engine Stalls During Trans. Engagement |
Models With A/T |
TC - Step 1) |
| Engine Stalls When Parking |
Models With PSP Switch |
FF - Step 2) |
| Engine Surge At Acceleration Or Cruise |
Ranger |
S - Step 1) |
| Erratic RPM |
Ranger |
S - Step 1) |
| Gasoline Fumes |
Models With CANP |
KD - Step 1) |
| Late Shift Into 4x4 High |
Models With A/T |
TB - Step 5) |
| Overdrive Cancel Indicator Off |
Models With A/T |
TB - Step 4) |
| 4x4 Low Light Always Off & Harsh Shift |
Models With A/T |
TB - Step 1) |
| 4x4 Low Light Always On & Shift Slipping |
Models With A/T induction and electrical connections are clean and tight |
TB - Step 1) |