My state doesn’t require emissions tests, so can someone please explain to me how the cars know when an emissions test is being administered? All I can imagine is that maybe the measuring probe creates enough backpressure that the emissions system notices something is different. Or is there normally something hooked up to the car’s electronics during the test (which would make it trivially easy to know when a test is going on)?
for the ten billionth time, the EPA emissions certification test is what we’re talking about here. This is the test each model of car has to pass before the manufacturer is allowed to put it on the market. It is a laboratory test with precisely-controlled parameters, among which are ambient temperature, engine warm-up time, a strictly controlled drive cycle, and so on. it’d be trivial for the PCM to notice that the ambient temp is exactly 25°C, the front wheels are spinning but the rear wheels are not, etc. and these lab tests do not use a probe stuck in the tailpipe, they actually clamp around a specially shaped exhaust outlet and collect the exhaust gases for analysis.
it has nothing to do with state-level inspection tests (if the state does that.)
The car’s onboard computer monitors steering wheel motion. In normal driving there is always some degree of adjusting the wheel even going straight ahead. In emission testing, the car is on a dynamometer with the steering wheel held still. If the computer didn’t sense any movement of the wheel, it kicked into clean-emission mode.
The people who discovered the scam borrowed a portable tester that fit in the trunk and monitored the actual exhaust out put while driving. I will see if I can find the other article I was just reading.
I’m not sure what prompted this, but it’s absurdly hyperbolic. If you’re going to respond to the question, just answer it without the snark.
Moderator Note
While jz78817’s post was out of line, that doesn’t entitle you to engage in insults and junior moderating. If you have a problem with a post, report it. No warning issued, but don’t do this again.
it came up a few times in the MPSIMS thread about this, and in an attempt to be humorous I increase it by an order of magnitude every time I respond. guess it fell flat.
This is just a cover story – actually, the EPA offers rewards to auto company informants who inform them about such cheating. Then they create a cover story like this one, to keep their whistle-blowers anonymous.
I have no idea if that is true or not.
But the EPA should start this rumor going around. It might scare the auto makers into not trying such cheats quite as often. And it might encourage some auto company workers on the inside to blow the whistle on other such as-yet-undiscovered cheating.