Cylinder Balance Test

This test helps identify a weak or non-contributing cylinder in engines with sequential PFI fuel systems. ECA shuts off fuel supply to each injector and measures RPM drop. It computes variation between cylinders and identifies weak ones. This test mode is entered from KOER SELF-TEST after all codes have been displayed. Within 2 minutes after codes have been displayed, lightly depress throttle (a 2-3 degree throttle angle is required, not a wide open throttle). After a brief stabilizing period, ECA will activate test procedure. Test will be repeated if throttle is depressed within 2 minutes of final code output. During second and third test sequences, percentage of allowable variation between cylinders is reduced. Service codes displayed during this test identify weak or non-contributing cylinder. See CYLINDER BALANCE TEST SERVICE CODES . 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. Total test time is about 3 minutes.

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
70	Cylinder No. 7
80	Cylinder No. 8
77	Retest

EEC-IV DIAGNOSIS BY SYMPTOM

Symptom	Application	Circuit Test
A/C Compressor Runs Continuously	2.3L & 4.9L	KM - Step 35)
A/C Does Not Cut Off During WOT	All Models	KM - Step 15)
A/C Not Functioning	All Models	KM - Step 1)
Black Exhaust Smoke	Except 7.3L	H - Step 1)
CHECK ENGINE Light Always On	Except 7.3L	ML - Step 1)
CHECK ENGINE Light Flashing With Erratic Idle	Except 7.3L	ML - Step 15)
CHECK ENGINE Light Never On	Except 7.3L	ML - Step 4)
CHECK ENGINE Light On Intermittently	Except 7.3L	ML - Step 10)
Difficult Start	Ranger 2.3L	NB - Step 25)
Engine Detonates	2.3L & 4.0L	KP - Step 5)
Engine Hesitates After Hot Restart	Except 7.3L	H - Step 21)
Engine Hesitation	Except 7.3L	S - Step 2)
Engine Lacks Power Or Loses Power	Except 7.3L	S - Step 2)
Engine Miss At Idle, Acceleration Or Cruise	Except 7.3L	S - Step 2)
Engine Runs Rough At All Times	Except 7.3L	S - Step 2)
Engine Stalls	Except 7.3L	S - Step 2)
Engine Stalls During Transmission Downshift	Models With E4OD	TC - Step 1)
Engine Stalls During Transmission Engagement	Models With E4OD	TC - Step 1)
Engine Stalls When Parking	Models With PSPS	FF - Step 3)
Engine Surge At Acceleration Or Cruise	Except 7.3L	S - Step 2)
Engine Surge At Idle With A/C On	2.3L	KM - Step 30)
Erratic RPM	Except 7.3L	S - Step 2)
Gasoline Fumes	Models With CANP	KD - Step 1)
Late Shift Into 4x4 High	Models With E4OD	TB - Step 5)
Low Idle With A/C on	Except 7.3L	KM - Step 43)
Overdrive Cancel Indicator Off	Models With E4OD	TB - Step 4)
4x4 Low Light Always Off & Harsh Shift	Models With E4OD	TB - Step 2)
4x4 Low Light Always On & Shift Slipping	Models With E4OD	TB - Step 2)
On models equipped with mass airflow system, ensure air induction and electrical connections are clean and tight.