If your vehicle is a 1995 or older, and has a GVWR, that is less than 8500LBS, it will be tested using a method called Acceleration Simulation Mode (ASM 25/25). This type of test simulates driving at 25 MPH using the dynamometer while applying a 25% load equated to your vehicle make and model. The inspector will insert a probe in your vehicle’s tailpipe to measure the emissions while the vehicle is driven on the dynamometer.
If your vehicle is a 1995 or older, all-wheel drive vehicle, or limited by traction control, or a vehicle that has a GVWR that is over 8500lbs, it will receive a Pre-Conditioned Two Speed Idle (PC TSI) Test. This type of test samples your vehicles emissions at two different RPM levels while your vehicle’s drive wheels are stationary (no drive mode simulation).