Need help with REX drive cycle

[chris_b]

I bought a 2017 REX a month ago. To register the car in CA, it needs to have a "smog check," which with the REX is simply a check on the OBD port of the drive cycle (emissions readiness monitors). My problem is that I (i) foolishly reset the ECU in the process of recoding), and (ii) now that I have done that, I can't get the drive cycle emission readiness checks (there are 3 still in the red), despite driving all over hell at different speeds. Does anyone know what it takes to set the emissions readiness monitors reset, so I can pass my smog check?

 

[ClaudeLecotur]

I have the same issue on my 2014 REX (57KMiles) here in Upstate NY. Have an appointment with the BMW dealer after a couple of private garages couldn't help me. Someone on another forum suggested to clear the codes, then drive with the rex nonstop about 80 miles and without locking the car taking for the inspection. I might try that before the appointment. Any other ideas?

 

[chris_b]

I have driven my 2017 REX several hundred miles under all different conditions, with no success on the drive cycle. I finally called a BMW dealer in my area and found someone who recommended two courses of action: drive the car a certain number of miles (~50) at 55 mph, or drive the car and run it through 10 cycles of driving 65 mph and letting the car coast down to 50 mph. I tried the first one last weekend, with no success. I may try the second one this weekend if I have time and can find somewhere to do the gymnastics described. Otherwise, I give up. The dealer said they could get the drive cycle done, so I likely will take it in for that. They are 50 miles away, so the logistics are a PITA.

 

[chris_b]

I got no response to my messages above, and I couldn't find any useful info on the Internet (and I am reasonably good at finding such information) so I thought I would share my experience with those Californians faced with this problem. I drove the car several hundred miles on the REX in all different conditions, no joy. In desperation, I contacted the closest dealer to inquire about this. They gave me some advice that seemed a bit strange, but I was down to try it: (i) drive the car at exactly 55 MPH for 50 miles; or (ii) drive the car and take it up to 65 MPH and let it coast down to 50 MPH, 10 times. I did (i) above- no success. I ultimately decided to take my i3 to the dealer because they said they could do this and I hadn't been able to register/transfer my car for 3 months.

Last week, I took my car to the dealer (50 miles, one way). They checked it out and said there was nothing wrong with the Rex, but I would have to bring the car back when the charge was reduced to the point where the Rex would run. Would have been nice to know before I drove 50 miles to get there. I explained that I had done the Rex reconfig and that would allow the Rex to run at 75 miles charge. They were good with that, but I had about 100 miles on the charge. They didn't want their mechanic to have to drive the car around until the 75 miles mark, so I said I would drive the car and return. I took the car out to the nearest freeway and drove +85 MPH to the next exit (about 10 miles) and returned with the car at about 65% charge.

They took the car back in (ostensibly, for the mechanic to drive the car and accomplish the drive cycle magic). Not long after the service writer told me that when the mechanic hooked the car back up to the scanner, he found that all of my drive cycle timers were green and he had completed the smog cert. They could not explain how this happened, except to say that maybe the motor was just ready to drop into a completed drive cycle and my relatively brief drive did the trick. I find this a bit hard to believe, and the really strange thing is that I was not running the Rex during my relatively high speed run.

Finally, after 3 months I got my reg and stickers. I don't know if my experience above is conclusive, but if I ever have this problem again, I will try the high speed run. I am not messing any further with the ECU config, so this should be a non-issue.

 

[ksnax]

I suspect BMW built this in as a feature to appease CA law (along with the ridiculous gas tank size). I'd guess it is intended to keep people from trying to game errors out of the system immediately before testing.

 

[alohart]

I suspect BMW built this in as a feature to appease CA law (along with the ridiculous gas tank size). I'd guess it is intended to keep people from trying to game errors out of the system immediately before testing.

This behavior occurs on any modern U.S. ICE for the reason that you wrote. It's not exclusive to BMW

 

[Whereitis]

I got no response to my messages above, and I couldn't find any useful info on the Internet (and I am reasonably good at finding such information) so I thought I would share my experience with those Californians faced with this problem. I drove the car several hundred miles on the REX in all different conditions, no joy. In desperation, I contacted the closest dealer to inquire about this. They gave me some advice that seemed a bit strange, but I was down to try it: (i) drive the car at exactly 55 MPH for 50 miles; or (ii) drive the car and take it up to 65 MPH and let it coast down to 50 MPH, 10 times. I did (i) above- no success. I ultimately decided to take my i3 to the dealer because they said they could do this and I hadn't been able to register/transfer my car for 3 months.

Last week, I took my car to the dealer (50 miles, one way). They checked it out and said there was nothing wrong with the Rex, but I would have to bring the car back when the charge was reduced to the point where the Rex would run. Would have been nice to know before I drove 50 miles to get there. I explained that I had done the Rex reconfig and that would allow the Rex to run at 75 miles charge. They were good with that, but I had about 100 miles on the charge. They didn't want their mechanic to have to drive the car around until the 75 miles mark, so I said I would drive the car and return. I took the car out to the nearest freeway and drove +85 MPH to the next exit (about 10 miles) and returned with the car at about 65% charge.

They took the car back in (ostensibly, for the mechanic to drive the car and accomplish the drive cycle magic). Not long after the service writer told me that when the mechanic hooked the car back up to the scanner, he found that all of my drive cycle timers were green and he had completed the smog cert. They could not explain how this happened, except to say that maybe the motor was just ready to drop into a completed drive cycle and my relatively brief drive did the trick. I find this a bit hard to believe, and the really strange thing is that I was not running the Rex during my relatively high speed run.

Finally, after 3 months I got my reg and stickers. I don't know if my experience above is conclusive, but if I ever have this problem again, I will try the high speed run. I am not messing any further with the ECU config, so this should be a non-issue.

I wonder if the lack of responses you got are due to confusion about exactly what you're asking. I'm not clear at all about what is the specific problem you're experiencing. Is it the Rex not turning on, not turning off, or something else?

 

[chris_b]

You are apparently (and perhaps others) not familiar with the CA (and other states) smog check requirement that an emissions drive cycle be completed before a smog test can be certified as passed. This applies to OBD2 cars only (and obviously, to the i3 Rex). Basically, the smog station hooks up their scanner to the diagnostics port and if the drive cycle shows as completed (all indicators green) you are good to go. If not, you fail.

 

[chris_b]

This behavior occurs on any modern U.S. ICE for the reason that you wrote. It's not exclusive to BMW

It occurs with any ICE vehicle with OBD2 diagnostics- 1996 and on. I have several other OBD2 vehicles (2 of which are BMWs) and the drive cycles are relative routine. You drive around for a week or two under varying conditions and all is good. With the i3, I put close to 300 miles on the car with the Rex running under significantly varying conditions and could not get the drive cycle to complete. The dealer I took my car to because they said they could make it happen said that what they do is drive the car at 65mph and let it coast down to 50mph, rinse and repeat 10 times and then the drive cycle will complete. In my experience this is unique to the i3 Rex. They never got a chance to try that because of the reason I explained in my post above. They were baffled by what happened and couldn't really explain it. All I did was drive really fast for about 15 miles, which is something I had not done in my previous 300 miles of driving. Go figure. In any event, I was thrilled that I could register my car after 3 months of trying to complete the smog test,