- Idle speed is erratic, speed varies up and down, too high or too low, cannot be adjusted to specification
- Warm engine has rough idle but performs OK above idle.
- Diagnosis II — Idle problems
- With fully warm engine, raise engine speed to 3000 RPM for about 5 seconds.
- Release the throttle and let the engine return to idle.
- Measure idle speed with a tachometer and check that:
- The idle speed is correct
- The idle speed does not vary more than 50 RPM
- The idle is not rough
If test passed, return car to customer
If test failed, perform diagnosis procedure II