Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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.
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, PCM 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 DIAGNOSTIC TROUBLE CODES table.
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 complete. Repeat Cylinder Balance Test. Total test time is about 3 minutes.
| 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 |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.