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Discussion Starter · #1 ·
I see another big thread about drive cycles back in 2013 for getting some kind of certificate in Massachusetts, but it didn't seem to have many specifics, or I may have scrolled past it a few times going over the long thread.

I'm in California where Chevy Volts are indeed required to get smog checks. I happened to have a CEL come on the month or so before and found it required an A/C coolant refill. Refilled, cleared the error, and it's been good a few days now. I drove around a few days, a bit on ICE, blasting the A/C on occasion. But the Smog Check place did me the courtesy of pre-checking the drive cycle and she said I was still very short on several items on the drive cycle. She used a little thing like a typical error code reader where a bunch of items popped up with checks or x's on them, and was frustratingly quick about unplugging it and not explaining what exactly I needed to do. I'm kind of tempted to see if I can buy one of those for myself.

With Gen 1 going on 10 years now, do we have any firmer sense of what one reliably needs to do to fulfill the drive cycle requirements so that I can get my car smogged? I'm seeing a lot of vague answers ranging from 60-160 miles on ICE, a full week's worth of driving/commuting, drive it hard, drive it normally, a certain number of cold starts, etc. Might there be other odd requirements? Run the A/C or other accessories? Is there a concrete list /anywhere/ we can look at these days?
 

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I do not know California stuff, but you are saying that there is no check engine light on and they plugged in and saw errors? Maybe... find a small shop that can read codes and ask them to clear them, in the mean time?
 

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Discussion Starter · #3 ·
I do not know California stuff, but you are saying that there is no check engine light on and they plugged in and saw errors? Maybe... find a small shop that can read codes and ask them to clear them, in the mean time?
No, this is different. I think in all cases Smog Checks require some amount of data on your car's computer. That data can be wiped because you disconnected the batteries (i.e. to swap out a dead one) or if like I did, there was a check engine light problem, you fixed it, and then cleared out the error (an option on my car error code reader). Most cars require a certain amount of driving so that the car collects enough data again for the smog check to use.

So with that data wiped out, I'm curious what I need to do to run the car enough to collect enough data for a smog check to run. This happened once and I just drove around about a week and that seemed to do it. I'm sort of looking to see if there are some specific things I can do so I might go through the drive cycle faster.
 

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I think I'm not up on the lingo -- what's "hold"? I know I can switch to Mountain driving mode (very rarely -- but I got to Sport driving mode a lot).
Your 2012 doesn’t have Hold Mode. That was added in 2013.
 
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I share frustrations on the lack of details regarding the drive cycle specifics needed for cars to complete the subsystem checks required for readiness - the Volt included. If you followed the steps in the MA thread (also in a steverino FAQ)...that seems to be best one can do. Like all things internet, there are some bizarre stories on drive cycles, in general, out there.

That said, I bought a $12 obd2 unit on Amazon (others have listed) and got the $5 Torque App for my android. The app came with a page that shows the readiness indicator's status overall. That will give you something to go off of. There is also a template you can drag onto a monitor page on the app that will show the readiness check status for the current drive cycle in real time. That way, you can have some idea when and how it is testing AND what isn't completing.

I did roughly the steps below late at night twice and did other drives randomly before and after. I didn't have the odb2 at the start of this, but it did get me as far as I think possible for my Volt.
-get fuel tank to just under 3/4 full
-Drive it until no charge and force extended range/ICE
  • put in mountain mode
  • drive it for few miles around town
  • take on highway, set cruise at 55 for 5miles
  • allow car to slow to stop without brakes
  • turn off mountain mode and drive until no charge again
  • Go home and park it for over 8hrs, no charging
  • turn on and open hood to force ice to engine warm at more normal-ish engine speed
  • put into mountain mode and close hood
  • Repeat the drive above

If you wish, on Friday I can capture and post an image of the torque app readiness screen for you so you can better decide about dropping 20 bucks.

Good luck!
Matt
 

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The key to drive cycles is there is an 8 hour gap between each use of the gas engine. My understanding is it takes three to 10 drive cycles to set the codes, depending on the car and the total amount of time the gas engine is in use.
 
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(Honestly, if owners are responsible for knowing when their vehicles are ready for smog checks, then it feels like it should be a legal obligation for manufacturers and/or states to document for those same owners how to meet that readiness criteria. "All readings will be valid if the following process is done. If some are still not ready, the car needs diagnosis and repair. These diagnosis and repairs are covered by the B2B warranty if applicable.")
 

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I agree with Hellsop that if a test is mandated, the criteria for evaluation and preparation should be documented. Along the lines of obermd, it isn't clear to me that the 8hours is actually time-based OR is a recommendation to ensure that [Temp ambient = Temp engine_coolant]. That is, I read somewhere (not on this forum) that some GM vehicles want those two temps to be within 3degF of one-another prior to warm-up as a check the engine was actually starting cold. Other places simply wanted the Tengine_coolant to be below a particular temp threshold. Still somewhere else indicated 8hrs was to check a leak rate of the evap system. So, who knows!? Argh.

Worse yet, on my Volt after 10hrs of sitting, I found those temps were, on one occasion, 5degF apart given that the air temp had changed rapidly overnight. This would be just one example of the many potential criteria that can cause a readiness check to not complete AND one would have no idea. In so far as a readiness cycle check might not complete, one can't be sure why it doesn't. And if the cycle completes and the readiness fails, the reason may be inactionable in cases in which no codes are created.

Cheers,
Matt
 

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(Honestly, if owners are responsible for knowing when their vehicles are ready for smog checks, then it feels like it should be a legal obligation for manufacturers and/or states to document for those same owners how to meet that readiness criteria. "All readings will be valid if the following process is done. If some are still not ready, the car needs diagnosis and repair. These diagnosis and repairs are covered by the B2B warranty if applicable.")
I'd put the diagnosis and repair under the emissions control warranty - if any part of the car causes the car to fail a smog check for any reason it's up to the manufacturer to fix it.
 
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Went through this on my 2012 after a 12V battery replacement. Ran the battery down, put it in Mountain mode, ran down the freeway about 30 miles, parked it and did it again the next day, AZ allow one item to be not ready but still passed it for emissions. Think it would take multiple free way rides to get the last item to clear.

Your Chevy repair shop should be able to tell you the routine to get it to clear. I used my Chevy mechanic neighbor to get the info to get mine past the DMV.
 

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Discussion Starter · #13 ·
If you wish, on Friday I can capture and post an image of the torque app readiness screen for you so you can better decide about dropping 20 bucks.

Good luck!
Matt
I'm quite willing to pick up some relatively inexpensive gear or apps (in the $20-30 range) so that I can know for sure. I'd be quite interested in the screen if you get a moment. Thanks!
 

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Here you go! At bottom is what the screen looks like. The "Torque Pro" app's "real time screens" can be modified however you want with whatever your reader can output. You swipe left/right to swap between screens. I setup 3 screens, each with different displays.

The app came with the "emissions readiness" display and had an option to add the "current drive cycle status" display. These two don't tell you more granularity by themselves, but at least give some feedback and other details for very little money.

Note also: the cheapo obd2 reader I bought can't check/monitor the heated catalyst readiness and that is the main one I'm struggling with. YMMV, as they say.

Bests,
Matt


Gadget Font Technology Multimedia Display device
 
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Discussion Starter · #15 ·
Here you go! ...
Thanks! So, I drove on Mountain mode for a good 75 miles and took it into the Smog Check place and initial checks verified the drive cycle was done.

HOWEVER. new wrinkle, at least for California drivers. In July 1, 2019, they added a regulation to check for Permanent Diagnostic Trouble Codes (aka Permanent Fault Codes) now available on newer (post-2010) cars:


Permanent sounds scary, but basically it's the double-secret-probation of error codes that will stick around after clearance until the car's been run long enough to verify the problem hasn't come back, like in my case an A/C fluid low. It means we need to run the car longer to clear out the trouble code. So there's a requirement in CA or other states that now monitor PDTCs for at /very least/ 15 warm-up cycles and 200 miles since clearance. (shorthand is the 15/200 criteria)

Some definitions (they're on that page):

Are there circumstances under which a PDTC will not cause a vehicle to fail a Smog Check inspection?

Yes. PDTCs will be ignored if the vehicle has completed at least 15 warm-up cycles and been driven at least 200 miles since its OBD information was last cleared.

What is a warm-up cycle?

A warm-up cycle means driving a vehicle so that the engine coolant temperature rises by at least 40 degrees Fahrenheit after the engine is started and reaches at least 160 degrees Fahrenheit.
 
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