[pbonsalb]

If you want the warranty, it’s only available for the 91 octane tune because as Dinan has explained in this thread, it has no idea what octane you will actually put in the tank.

[epicaccord]

Has anyone purchased the E85 tune for $800 for F90 M5 yet?

[RoseyLA]

I'm curious, if I'm running the E85 tune and I am unfortunately not able to fill up with E85, is it safe to run 91 until i can fill with E85? TIA

[pbonsalb]

As Dinan wrote on the previous page:

Currently switching back and forth between octane maps would require a trip to a dealer to get reflashed. Not ideal by any means. Work is ongoing on getting a DIY option available.

The E85 tune has an operating range of E60-E85 so pump variability will be of little to no concern.

[RoseyLA]

Originally Posted by pbonsalb

As Dinan wrote on the previous page:

Currently switching back and forth between octane maps would require a trip to a dealer to get reflashed. Not ideal by any means. Work is ongoing on getting a DIY option available.

The E85 tune has an operating range of E60-E85 so pump variability will be of little to no concern.

I saw that thanks. So please clarify. If I was in a pinch and needed to add a 1 gallon of 91 to my gallon of E85 (in order to get my ethanol station ) I'd be running ~96 octane or E50. Would that be ok for the engine while running the E85 tune?

[pbonsalb]

Is E50 less than the operating range of E60-E85?

[epicaccord]

You should be fine in an emergency. According to E85 calculator you can have up to 6 gallons of 91 gas make it E60 total in the tank. I talked to Dinan rep and he said our tanks can have all E85 no problem with their tune, as low as E60. It seems like noone with M5 has tried this particular tune.

[Dinan_Engineering]

Originally Posted by RoseyLA

I'm curious, if I'm running the E85 tune and I am unfortunately not able to fill up with E85, is it safe to run 91 until i can fill with E85? TIA

Originally Posted by epicaccord

You should be fine in an emergency. According to E85 calculator you can have up to 6 gallons of 91 gas make it E60 total in the tank. I talked to Dinan rep and he said our tanks can have all E85 no problem with their tune, as low as E60. It seems like noone with M5 has tried this particular tune.

What epic said -- Operating range of the E85 tune is down to E60. Below that (like E50) and the car is going to not be happy. You could likely limp around on E50 if absolutely needed for small distances but you would want to be as easy on the car as humanly possible. I still wouldn't recommend it though. With the lesser ethanol content you are playing a temperature game particularly at higher boost levels and knock/detonation become a large concern as a result.

[epicaccord]

Originally Posted by Dinan_Engineering

What epic said — Operating range of the E85 tune is down to E60. Below that (like E50) and the car is going to not be happy. You could likely limp around on E50 if absolutely needed for small distances but you would want to be as easy on the car as humanly possible. I still wouldn't recommend it though. With the lesser ethanol content you are playing a temperature game particularly at higher boost levels and knock/detonation become a large concern as a result.

I know you probably get this question a lot, but you guys are ok with full E85 in our tanks with the E85 tune and no other modifications? Our cars aren't flex fuel so how's that possible 🤔

[Dinan_Engineering]

Originally Posted by epicaccord

I know you probably get this question a lot, but you guys are ok with full E85 in our tanks with the E85 tune and no other modifications? Our cars aren't flex fuel so how's that possible 🤔

Yes, the E85 tune/fueling on an otherwise stock car is perfectly fine. As far as how -- some callibration/software magic is about the depth of my knowledge on the topic. Ultimately the stock fuel system has enough bandwidth/capability to be tweaked through software and allow necessary flow to support ethanol.

[RoseyLA]

Originally Posted by Dinan_Engineering

What epic said -- Operating range of the E85 tune is down to E60. Below that (like E50) and the car is going to not be happy. You could likely limp around on E50 if absolutely needed for small distances but you would want to be as easy on the car as humanly possible. I still wouldn't recommend it though. With the lesser ethanol content you are playing a temperature game particularly at higher boost levels and knock/detonation become a large concern as a result.

Thank for the reply.

Logistics question; so I get my car tuned for e85 at a local dealer. I have 91 in the tank and need to drive to get e85 how do you recommend I handle that? Or could I fuel up with E85 without the tune and drive to the dealer? thanks

[pbonsalb]

Run a blend of E30-E40, which the stock tune can handle, in half a tank of gas. Drive mildly after flashing to the gas station and fill up with E85.

[epicaccord]

Originally Posted by Dinan_Engineering

Yes, the E85 tune/fueling on an otherwise stock car is perfectly fine. As far as how — some callibration/software magic is about the depth of my knowledge on the topic. Ultimately the stock fuel system has enough bandwidth/capability to be tweaked through software and allow necessary flow to support ethanol.

Ok makes sense. I have a 3.5 bar map sensor installed, will that mess with the E85 tune? The stock one is 2.5 bar.

[pbonsalb]

The original map sensors in my 2018 M5 say 3.5 bar on them.

[Dinan_Engineering]

Originally Posted by epicaccord

Ok makes sense. I have a 3.5 bar map sensor installed, will that mess with the E85 tune? The stock one is 2.5 bar.

Originally Posted by pbonsalb

The original map sensors in my 2018 M5 say 3.5 bar on them.

Both stock F90 M5 MAP sensors -- 13627843531 (Early 2018) & 13628644433 (Late 2018+) -- are 3.5 bar so there should be no issue.

If they were different however the tune would need to be altered and the sensor table rescaled so that reporting was correct and everything jived.

[nsanity]

Originally Posted by pbonsalb

The original map sensors in my 2018 M5 say 3.5 bar on them.

Are you talking the MAP's at the Intake or at the Inlet manifold.

They are different.

The ones at the inlet manifold are 2.5 bar.

Carbahn's stage 3 tune changes these. See this post for the location - part 9.

https://f10.m5post.com/forums/showpo...9&postcount=18

(yes its an F10, but same same).

[pbonsalb]

I saw a couple that were 3.5 bar but did not look for more. Now you have made me curious so I will look for the others and apologize for the incorrect statement.

I just did a little research and apparently F10 M5 BM3 tunes had an option for 3.5 bar pre-intercooler map sensors. They could give better resolution than scaling the 2.5 bar. I will look at my F90 M5 BM3 tune to see if it has the same option and, if so, consider picking up a set of 3.5 bar for the pre-IC. It looks the the existing 3.5 bar sensors are the post-IC.

[nsanity]

Originally Posted by pbonsalb

I saw a couple that were 3.5 bar but did not look for more. Now you have made me curious so I will look for the others and apologize for the incorrect statement.

I just did a little research and apparently F10 M5 BM3 tines had an option for 3,5 bar pre-intercooler map sensors. They could give better resolution than scaling the 2.5 bar. I will look at my F90 M5 BM3 tune to see if it has the same option and, if so, consider picking up a set of 3.5 bar for the pre-IC. It looks the the existing 3.5 bar sensors are the post-IC.

I can 100% say for certain that the ones on the inlet manifold are 2.5 bar, and the ones just after the intercoolers are 3.5 bar.

And the tune 100% needs to be scaled for it.

[pbonsalb]

If the option is there with BM3, I will look further into the benefits. Selecting the option would change the scale. The option appears to be there, in the 4th from last screenshot in this link:

https://www.protuningfreaks.com/prod...mw-f90-m5-tune

I just took a quick look under the hood and these other map sensors must be buried pretty far down. Do you have any pictures of their location? The 3.5 bar sensors are pretty cheap at about $65 each but it might take me some time. No DIY are popping up. I think they are sort of at the front corners of the intake manifolds but am not sure. Not a priority so this might wait until I have to get in there for something else.

This is the best I have found for a DIY and it is for the F10, but likely pretty similar:

https://f10.m5post.com/forums/showthread.php?t=1324228