Yep, agree with VDC. If the computer sees that the front wheels are moving (FWD) and the rear wheels aren’t, it shifts into test mode then 30 minutes or so later when the car is on the road, it goes back to normal mode again.
I still believe there are some red faces at the EPA but we do heavily rely on “testing” as the end all do all. Minnesota quit testing years ago because the governor determined that the only ones benefiting were the testing vendors.
I imagine the EPA didn’t think any auto company would be crazy (stupid) enough to criminally evade the law. Now VW will likely have to fix all the diesels with software subersion, and then will have to satisfy the government that any new cars won’t have the same software cheat going forward. Otherwise, no more diesels from VW. I think VW dealers should sue VW for lost business because of their criminal practices.
After the last economic collapse I remember Alan Greenspan saying something to the effect that he never thought bankers would do the things they did. He just thought they were above being that greedy. Surprise. Now if Alan was a little red in the face after trusting his buddies, I still can’t believe that there aren’t at least a few at EPA and maybe some early retirements with a bonus of course.
ok, makes sense this thing with the front and rear wheels, but in Maryland they don’t put your car on those rollers anymore. They stick some probe up the exhaust pipe and rev the engine, so none of the wheels are moving.
but in Maryland they don't put your car on those rollers anymore. They stick some probe up the exhaust pipe and rev the engine, so none of the wheels are moving.
This is true on 1977-1995 passenger cars. 1996 and newer just get the OBD II plug in test.
“They stick some probe up the exhaust pipe and rev the engine, so none of the wheels are moving.”
What you’re describing is a two-speed idle test . . . 2 engine speeds, to be more specific
Not as precise as a tailpipe test while doing a dyno run. I suspect the state of Maryland is trying to streamline the process and save somebody some money.
In California, this is how it works. This may not be 100% accurate, but I believe it’s pretty close
2000 and newer gasoline vehicles with OBD2 get a plug-in test
1998 and newer small diesel powered vehicles with OBD2 get a plug-in test
1999 and older gasoline vehicles with OBD2 get a dyno run, if they’re below 10000lbs GVWR and are physically able to fit on the dyno. That eliminates duallies
1997 and older small diesels and all large non-OBD2 diesel powered vehicles get an opacity test
Class 4 and above gasoline powered vehicles get a two-speed idle test. They’re simply too big for the dyno, plus they’re not OBD2 compliant, anyways
For any “newbies” reading this . . . class 4 and above vehicles are not OBD2 compliant. That changes everything, as far as emissions and diagnosis goes. I do smog inspections of all kinds, dyno run, two speed idle and plug-in, and I also do opacity inspections. It’s “interesting” to see what kinds of emissions these non-OBD2 gasoline powered vehicles are allowed to have, and still pass the tailpipe test. 150Hc, for example. When was the last time a gasoline powered vehicle was allowed to have that, and still pass . . . ?!
These situations come up all the time. The truck is scheduled to be emissions tested, and it passes with extremely high numbers. In all likelihood, something that affects emissions is not quite up to par, but it’s legal for another 2 years. So in some sense, there’s no sense of urgency to repair anything, as far as emissions are concerned.
I wasn’t implying that anybody reading this was a newbie, but I rambled on, just in case somebody might find it interesting 