How strict is a "drive cycle"?

Question

This answer lists the steps in a GM "drive cycle", for purpose of running certain diagnostic tests, and (?) re-calibrating certain parameters. (In my case, after replacing a heated O2 sensor.)

In particular, the listed steps begin with a cold start, followed by a 2-1/2 minute idle, followed by a half-throttle acceleration to 55 mph. To do this, it seems like I would need to drive to a highway on-ramp, sit for an extended period while the engine cools, and the perform the test steps.

Does it need to be that exact? Or, can I cold start, do the idle, drive on city streets to a highway, and then resume the test with the accelerate to 55 mph?

Answer 1

While the parameters of a drive cycle are fairly strict, how you get them done usually isn't. What I mean by that is, in order for the drive cycle to complete, you need to hit all of the parameters, but it usually doesn't matter how you do that. In a perfect world, we all would have a chassis dyno which would allow us to exactly follow the steps, but we all know it's not a perfect world, which also includes the engineers who designed the tests.

What needs to happen is each step needs to be completed as described, but (for the most part) the order the steps get completed in usually doesn't matter and what happens between the steps is also of little consequence. Obviously, the first two steps (cold start/idle) should most likely be completed first and are probably the easiest to accomplish.