General Pre-Test Preparation for a Snap-Acceleration Opacity Test

What the Test Measures

Ontario's DriveON program uses SAE J1667, the snap-acceleration smoke test, for heavy-duty diesel opacity measurement. The procedure measures exhaust smoke opacity as a percentage against model-year limits. This article covers vehicle readiness. Yard layout and multi-truck logistics are a separate topic.

The Technician Performs the Test

The snap-acceleration procedure itself must be carried out only by an authorized technician using approved equipment. Vehicle owners and drivers should not attempt to reproduce the inspection procedure themselves.

Vehicle Readiness Before the Appointment

• Make the exhaust outlet accessible for approved opacity-testing equipment
• Position the vehicle where it can be inspected safely without blocking yard traffic
• Have vehicle identification and odometer information ready for the inspection record
• Allow enough time for the engine to reach normal operating temperature
• If several units are due, stage them in order so testing can proceed sequentially

Maintenance Issues to Address

Keep to manufacturer service intervals for the air intake, fuel system, and aftertreatment components. Report warning lights or known aftertreatment problems before the appointment so they are not a surprise on test day. These are normal maintenance practices — not a method to force a specific opacity number.

What Does Not Guarantee a Pass

No legitimate provider can promise a pass. Last-minute “tricks,” incomplete maintenance, or attempting to mimic snap accelerations on your own do not replace the official procedure. Compliance is determined only by the authorized inspection result against the applicable opacity limit (and OBD requirements where they apply).

See Fleet DriveON compliance basics and DriveON calendar triggers, or visit Piotr Service to book.