TheMK
Posts: 127
Joined: Tue Sep 18, 2018 8:57 pm

Re: New to me 15' REX Certified Pre Owned no start REX?

Thu Feb 07, 2019 10:36 am

joeblow wrote:because we are high in the mountains and far from everything. For me, cold soaking seems to be the smoking gun.


I have issues with starting in sub-freezing temperatures. What are the temperatures like around where you are, also what's your elevation? I'm at around 6000 feet (in Utah). I use ethanol-free too, but switched from 91 octane to 88 octane- it seems to start easier now, though I'll go back to 91 this summer. I almost wonder if the REx's ECU doesn't put enough of a 'choke' (it's not carbureted, but think about the fuel injection analog) on the fuel system when starting in cold temperatures, which is why we have this problem. Right now it's 15F, though my car has been sitting in the garage.

EDIT: I should mention that I did get my REx started without any drama today.

joeblow
Posts: 16
Joined: Wed Dec 12, 2018 1:31 pm

Re: New to me 15' REX Certified Pre Owned no start REX?

Fri Feb 08, 2019 9:21 am

Sounds like we may be neighbors. I am at 7000ft in Kamas, Utah. Are you in Park City? My wife works at St. Regis and after working a night shift and leaving it cold soaking in the employee parking lot on the Jordanelle side, the REX will not start sometimes. Also going to the movies and then trying to start on the way home we have had issues. Obviously we are talking -10deg sometimes so it is cold. We have been using 91OCT ethanol free but I am starting to think we should go with the 88OCT with ethanol which should start easier. Heck the more ethanol the netter if light off is the issue. E85 might be even better?

jadnashuanh
Posts: 4345
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: New to me 15' REX Certified Pre Owned no start REX?

Fri Feb 08, 2019 3:31 pm

E85 might trash the engine...if I remember correctly, none of the BMWs sold in the USA are rated for use of more than E10, maybe E15.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

TheMK
Posts: 127
Joined: Tue Sep 18, 2018 8:57 pm

Re: New to me 15' REX Certified Pre Owned no start REX?

Fri Feb 08, 2019 11:36 pm

joeblow wrote:Sounds like we may be neighbors. I am at 7000ft in Kamas, Utah. Are you in Park City? My wife works at St. Regis and after working a night shift and leaving it cold soaking in the employee parking lot on the Jordanelle side, the REX will not start sometimes. Also going to the movies and then trying to start on the way home we have had issues. Obviously we are talking -10deg sometimes so it is cold. We have been using 91OCT ethanol free but I am starting to think we should go with the 88OCT with ethanol which should start easier. Heck the more ethanol the netter if light off is the issue. E85 might be even better?


Unfortunately, I do not live in Park City though I visit often and am very familiar with the area (we rent a house or condo for a month during the summer there-escape the valley heat). I live up at the top of the Bountiful bench, so my elevation is more like ~5500 rather than 6000, I rounded up to make a bit of a point. The recent snow storm left me unable to go anywhere on Wednesday, and when I did drive down on Thursday, there was definitely a bunch more up at our house than down by I-15. I've been to a couple of receptions at the St. Regis, though always from the Deer Valley side. In the valley there are more fuel options, I can get ethanol free in both 88 and 91 octane varieties. I'm not sure how E10 affects winter starting, but my guess is that it might make it easier, it seems like most of the mainstream gas stations around here have winter-mix fuel which has additives for cold starting.

Once I get the REx engine running, I'm home free. I can even clear the check engine light, and it will not come back on... until the next cold soak start. If you get stuck somewhere where the REx isn't wanting to start, try the emissions testing mode (http://www.mybmwi3.com/forum/viewtopic.php?t=2075). The great thing about this is you can attempt to start it multiple times with that, where as when doing normal driving with the REx, it only tries once to start.

joeblow
Posts: 16
Joined: Wed Dec 12, 2018 1:31 pm

Re: New to me 15' REX Certified Pre Owned no start REX?

Sat Feb 09, 2019 9:24 am

We were in the SLC Avenues until 4 years ago when we moved up the hill to escape the inversion.

I got my Bluetooth OBD2 port dongle to work with my Tourqe Pro app on my phone so I can clear the codes on the fly and keep retrying the REX till it starts. The process is a little finicky and the wife is not patient enough for it. If it happens to her she is less likely to get it going for that reason.

I am going to go with low OCT ethanol fuel on my next fill up and try that out. I think it is the easiest to try before going more extreme.

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