What can a technician do to help stabilize the idle RPM during a TSI smog test?

• A. Activate the A/C to load the engine slightly.
• B. Increase idle by revving the engine manually.
• C. Turn on the headlights to load electrical load.
• D. Remove the battery to reset idle.

Answer: (A)

During a Two-Speed Idle (TSI) smog test, keeping the engine idle within a tight RPM range requires a controlled load on the engine. Turning on the A/C adds a small, predictable load via the compressor, prompting the engine control system to compensate and stabilize the idle speed. This helps prevent idle fluctuations when the test analyzer measures the RPM, making the reading more reliable. Revving the engine manually, using headlights for load, or removing the battery either creates nonstandard conditions, is unpredictable, or disrupts the engine’s idle learning, which is less effective for achieving a stable idle during the test.