California Smog Check Inspector Practice Test

What is the RPM tolerance during an ignition timing functional test if no manufacturer’s specifications are provided?

1. +/- 50 RPM

2. +/- 75 RPM

3. +/- 100 RPM

4. +/- 150 RPM

The correct answer is: +/- 100 RPM

During an ignition timing functional test, if no manufacturer’s specifications are available, a tolerance of +/- 100 RPM is applied. This standard tolerance is established to account for variations and ensure that the engine operates within acceptable limits during the test. When manufacturers deliver specifications for ignition timing, they often include specific RPM values alongside tolerances that reflect the designed capabilities of the engine. However, in situations where such specifications are absent, the +/- 100 RPM range is a commonly accepted benchmark. This tolerance allows for reasonable fluctuations that may occur due to variables such as engine condition, operating temperature, and inherent mechanical variations. By utilizing this parameter, inspectors can maintain a consistent approach to evaluating ignition timing without being overly restrictive, thereby facilitating more accurate assessments of vehicle performance and emissions compliance.