TheMK
Posts: 140
Joined: Tue Sep 18, 2018 8:57 pm

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

Fri Jan 04, 2019 11:24 pm

Hence why I'm not brave enough to try it. Catalytic converters would also get plugged up (with enough use) and that won't be cheap. The only engine of mine I'd seriously try it in is my snowblower- conventional oil, carburetor, basically no exhaust system, not sure how well it would run, as it's not a particularly high compression engine.

Yes I'm at about 6000ft.

PBNB wrote:I run my Rex every other day for 20 min intervals to keep the fuel moving.

This is just my take on possibly preventing fuel system issues. I am interested to hear what others are doing to keep the Rex running smoothly.
I guess that's supposed to be the point of the "maintenance cycle". I'm not sure just running the maintenance cycle is good enough, however it's there as an idiotproofing method. Jim brought up oil sludge, and another thing that can cause that is low engine temperatures. You really need to get the engine fully up to temperature (and idealy let it run for a bit at temp too) to "clear the pipes". Maybe throw in a bottle of Techron or other stabilizer if it's going to sit for awhile.

Starting it every other day is probably a bit excessive, and needlessly creates cold starts. I'd say try every week or every other week, but instead of 20 minutes, maybe 30 or 40 minutes to let things run a operating temp for a bit. This is just my 2 cents.

jadnashuanh
Posts: 4488
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

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

Sat Jan 05, 2019 6:54 pm

The REx runs for at least 10-minutes before it can produce full output, so it's likely that it would run longer than 10-minutes once turned on.

Oil sludge can occur when using an all-synthetic oil and leaded (even low-lead) gasoline. Even disregarding what tends to happen to the catalytic converter, that lead can mess up the oil as well. The Rotax aircraft engine is designed to run on unleaded car gas. You can't buy that on an airport, so the manual tells you how to deal with it if you must buy it there. Unleaded isn't readily available on an airport except at a very few places. So, the 100LL use in many GA aircraft is what's needed. The manual calls for halving the oil change intervals when you need to use the 100LL, which would be similar for a car engine.

The REx is pretty small, so will tend to warm up fairly quickly.

I think if you're not going to use the REx all that often, some fuel stabilizer is probably a good idea. I will say that my GT sits in the garage for sometimes months at a time without running, and I've not experienced operational problems with it. The REx uses a pressurized fuel system that, in theory should help both retain the more volatile components and limit contamination/degradation of the fuel.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

joeblow
Posts: 25
Joined: Wed Dec 12, 2018 1:31 pm

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

Sat Jan 05, 2019 8:36 pm

I get home tomorrow so I will scan the car and try to do the emissions engine start hack too. I am guessing that the REX was NOT tested during the Certified BMW process but I could be wrong. The 12V I guess could be causing issues even though it shows good. I might just throw a battery conditioner on it anyway. I was planning on running the REX at least once a week to keep it fresh and we have ethanol free at our local gas station too which we run exclusively in our ICE cars so that was not going to change with the i3.

Either way we have an appointment on the 7th at the dealer if none of the above works. :D

jadnashuanh
Posts: 4488
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

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

Sun Jan 06, 2019 12:59 am

If I remember correctly, BMW warns not to try to charge the 12vdc battery. If you really want to, you need to disconnect the HV battery to isolate it. Somewhere, somebody posted the instructions and warning, but it's been awhile since I read it.

An i3 is not an ICE with a simpler electrical control circuit so there are some functional differences and cautions that must be adhered to to prevent damaging either it or become a danger to you as well. High voltage and high current are nothing to play around with unless you know what you're doing and understand the system.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

joeblow
Posts: 25
Joined: Wed Dec 12, 2018 1:31 pm

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

Sun Jan 06, 2019 1:12 am

Well noted however if the 12V battery is removed from the vehicle or at lease one lead is pulled it should be isolated and not any potential risk that I can see? No matter how sophisticated the rest of the car is it is still a 12V battery that has charging needs like any other.

TheMK
Posts: 140
Joined: Tue Sep 18, 2018 8:57 pm

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

Sun Jan 06, 2019 12:19 pm

One thing to note, the REx is not started from the 12V battery. Instead, power from the high voltage system turns the generator over to spin the REx engine. If your 12V was dead, then you wouldn't even get as far as putting the car in drive readiness and driving on electric power, at that point though the DC to DC converter turns on, which acts like the alternator in an ICE car, charging the 12V battery and powering the accessories load. If I recall correctly the DC to DC converter also runs while the car is charging.

joeblow
Posts: 25
Joined: Wed Dec 12, 2018 1:31 pm

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

Mon Jan 07, 2019 9:26 am

Well little update. Tried the emissions start hack but the car said I HAD to reduce the charge below 75% to start it, so basically the same as HSOC. So I started to drain the battery then just gave up as it seems the climate control is not working either. I was trying to run the heater to suck down the HV battery and it would just blow cold air. So having both issues I got fed up. Also I could not scan the car with any of my scanners. I tried a handheld and a dongle using Torque Pro and neither would work. My wife then reminded me we have both 4 years of warranty and a full parts coverage as well so I just called roadside assistance and they will take the car to the dealer. I will follow up with what they find out. Besides we have two days of winter storm up here so not a bad time to have the car worked on for free ;)

joeblow
Posts: 25
Joined: Wed Dec 12, 2018 1:31 pm

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

Tue Jan 08, 2019 12:31 pm

OK another update. The dealer said the scan showed random multiple misfires on the REX. They changed the spark plugs and coil packs and cleared the codes and that fixed it. They also said heat likely did not work because the SOC was low which makes no sense to me as the car was plugged in and fully charged when I tried to run the heat? So I am not sure the heat is working right or not yet. I will report back how the REX works when I pick it up.

TheMK
Posts: 140
Joined: Tue Sep 18, 2018 8:57 pm

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

Tue Jan 08, 2019 12:47 pm

I guess in a vain attempt to simulate an ICE car, the heater (or aircon for that matter) doesn't run while the car is in accessories mode even though the blower is running and the climate control panel looks normal. To run the heater, you have to engage drive readiness, or turn on comfort climate control from Settings->Climate. TO add even more to this confusion, if you were in drive readiness and then open the drivers door (which puts the car back into accessories mode), then the heater will continue to run. If you press the power button to leave drive readiness the whole climate control shuts down.

jadnashuanh
Posts: 4488
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

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

Tue Jan 08, 2019 4:16 pm

If you want to suck the battery level down, probably the easiest way on a REx would be to open a window(s) and tell it to precondition the cabin. The REx uses resistance heating to produce heat, and with the windows open, it would have to work the hardest as a lot of the heat would just go outside.

As you found, the maximum of 75% SOC is the threshold required for the REx to even consider turning on, regardless of the mode. It will run for at least 10-minutes, and there must be someplace for that energy to go without overcharging the batteries.

The i3 is not a 'normal' ICE vehicle. In some ways, it might seem logical to use the engine coolant from running the REx to heat the cabin, but the additional complexity and weight for the infrequent use of the engine, IMHO, just doesn't seem to tip the scale to making it happen.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

Return to “BMW i3 Rex Specific Discussions”