Flex fuel on stock hardware?

[Sndmem3s]

Thinking about pulling the trigger on a BM3 flex fuel kit on my F80. Currently running ACN 91 stage 1 with charge pipes as my only hardware mod.

I’ve read that E30-ish max is generally the safest blend to run on stock plugs and fueling system.

Is this true in most cases?

Is there any way to adjust the parameters on the OTS flex fuel map to max out at E30? I may be overthinking it.

Thanks!

[F80RN]

I’m not sure if this helps you, and I’ll leave the more intricate parts to more knowledgeable people. But I’ve been on a custom flex fuel tune for something around 1.5 years, before that I was on the OTS BM3 flex tunes. No issues, but I’ll change plugs and boots annually (is this overkill? Maybe. But I do plan on being the final owner for this car so whatever I can do to keep it in tip top shape is worth it to me.


Generally speaking, I’ve topped out at e60 without issue. However I only do that once ever couple top offs; a good idea would be to clean the injectors and then run the fuel filter kit for a better peace of mind. The explanation I remember being told is that you don’t really know what gunk exists within your fuel system, so by cleaning out the injectors and then installing the filter you can prevent gunk from entering the injectors.


Something along those lines.

[Sndmem3s]

Originally Posted by F80RN

I’m not sure if this helps you, and I’ll leave the more intricate parts to more knowledgeable people. But I’ve been on a custom flex fuel tune for something around 1.5 years, before that I was on the OTS BM3 flex tunes. No issues, but I’ll change plugs and boots annually (is this overkill? Maybe. But I do plan on being the final owner for this car so whatever I can do to keep it in tip top shape is worth it to me.


Generally speaking, I’ve topped out at e60 without issue. However I only do that once ever couple top offs; a good idea would be to clean the injectors and then run the fuel filter kit for a better peace of mind. The explanation I remember being told is that you don’t really know what gunk exists within your fuel system, so by cleaning out the injectors and then installing the filter you can prevent gunk from entering the injectors.


Something along those lines.

Nice! I guess my preconceived notion for flex fuel was that I would need colder plugs and a LPFP. I didn’t realize I could just get the kit & tune and keep everything stock and still safely run E30 and higher

[StockholM3]

I've ran E30 all year until winter with stock fuel system and had no issues.
I did change to colder spark plugs so I can't really say if the originals work, but you should probably change yours fairly soon anyway.
Once every one to two years for a tuned engine sounds reasonable.

[Sndmem3s]

Originally Posted by StockholM3

I've ran E30 all year until winter with stock fuel system and had no issues.
I did change to colder spark plugs so I can't really say if the originals work, but you should probably change yours fairly soon anyway.
Once every one to two years for a tuned engine sounds reasonable.

I just changed my stock plugs a few weeks ago when I replaced my valve cover lol the flex fuel kit is a new idea (already ordered it), wish I would’ve done colder but oh well.

Sounds like E30 should be fine.

[Hotflare]

Been on bm3 flex stg 2 for a year now. F8S plugs and the bend kit. I run from e45 to full e with no issues. Just changed my filter after 10k miles and it was nearly clean.

As a cali car I’d recommend this combo since we have shit fuel. 2nd owner of mines and it was from out of state so I know it saw 93 all its life til the last 3 years with me (2018 m3c).

Long story short, do what I did with stock turbos and you’ll be fine

[Sndmem3s]

Nice. I’ve had the BM3 kit and multimap tune now for a couple weeks. I’m just staying between E30 & E40 without a bend kit or upgraded plugs.

Everything feels great so far

[Sndmem3s]

Update: misfire city on cylinders 4 and 6. Gas flavored white smoke out exhaust. lol

4th tank of around E35-40

[lookitsapples]

Originally Posted by Sndmem3s

Update: misfire city on cylinders 4 and 6. Gas flavored white smoke out exhaust. lol

4th tank of around E35-40

Check or change our your injectors. I've been running the flex fuel kit with the bend calibration filter and been running full e85 and cycling through 91 octane every so often for several years now without issue

[Jaizero]

Originally Posted by Sndmem3s

Update: misfire city on cylinders 4 and 6. Gas flavored white smoke out exhaust. lol

4th tank of around E35-40

What plug gap are you running?

Should be .022-.023 according to BM3

[Sndmem3s]

Originally Posted by Jaizero

What plug gap are you running?

Should be .022-.023 according to BM3

Yep, getting the plugs gapped to this, they were stock (although very new).

[Sndmem3s]

Originally Posted by lookitsapples

Check or change our your injectors. I've been running the flex fuel kit with the bend calibration filter and been running full e85 and cycling through 91 octane every so often for several years now without issue

Yep, shop is doing the diag so we’ll see. My plugs need to be regapped too, and the Bend kit is sounding appealing.

It went into limp right after a fill up as the car was still adjusting to the E content, was driving completely normal with feather throttle. I feel like that sounds like injector issue

[Jaizero]

Have you done any logs to make sure the car is doing what it's supposed to be doing?

It amazes me that people think they can just slap a tune on without actually making sure the car is running correctly while tuned.

[WANTED///M]

Should i install new injectors if i want to have a flex fuel kit for E85. My car has been running oem injectors with a bm3 stage 2 ots map for 30k miles now. What should i change in order to run bm3 flex fuel kit for E85. Trying to prevent any damages to car before installing my kit.

[Sndmem3s]

Originally Posted by WANTED///M

Should i install new injectors if i want to have a flex fuel kit for E85. My car has been running oem injectors with a bm3 stage 2 ots map for 30k miles now. What should i change in order to run bm3 flex fuel kit for E85. Trying to prevent any damages to car before installing my kit.

I would just buy a Bend fuel filter kit and gap your plugs to .022-.023. OEM injectors seem to to be fine from what I understand. Going through this journey myself. Main reason injectors fail is because the E acts as a solvent in your fuel tank and can loosen up any debris which can mess with your injectors. I’d also start with a lower E% mix when you first start mixing and slowly work your way up to E50-E60 max. Full E85 on stock fuel pumps is counterproductive.

Someone may correct me on all this but this is what I’ve gathered personally

[n8dgr84]

Originally Posted by Sndmem3s

I would just buy a Bend fuel filter kit and gap your plugs to .022-.023. OEM injectors seem to to be fine from what I understand. Going through this journey myself. Main reason injectors fail is because the E acts as a solvent in your fuel tank and can loosen up any debris which can mess with your injectors. I’d also start with a lower E% mix when you first start mixing and slowly work your way up to E50-E60 max. Full E85 on stock fuel pumps is counterproductive.

Someone may correct me on all this but this is what I’ve gathered personally

This is all correct, however, I'd recommend the F8S spark plugs and a custom tune like the one I got from Ata_T1T . He was able to lower the max pressure in the HPFP from 3600 to 3300 (3000psi is stock) for E60 which helps keep the injector gates from breaking and potentially blowing a motor.

[WANTED///M]

Any one experience a custom tune from blend calibration? Was thinking about getting a custom tune from them and also purchasing the blend filter kit.

[carbon-14]

I have a user stage 3 LPFP from Vader solution for sale…. Less than 5K miles. I was able to get 700 RWHP without issues. Switching my setup. Going single turbo with stg 4 LPFP

[Vantablack]

Originally Posted by Sndmem3s

I would just buy a Bend fuel filter kit and gap your plugs to .022-.023. OEM injectors seem to to be fine from what I understand. Going through this journey myself. Main reason injectors fail is because the E acts as a solvent in your fuel tank and can loosen up any debris which can mess with your injectors. I’d also start with a lower E% mix when you first start mixing and slowly work your way up to E50-E60 max. Full E85 on stock fuel pumps is counterproductive.

Someone may correct me on all this but this is what I’ve gathered personally

I’m planning to go FlexFuel Stage 1 in my M4. Did you ever figure out what went wrong with your car?

I’m currently on Stage 1 ACN 91 with NGK 97506 plugs gapped to .022. I was planning to get the Bend Calibration filter kit and then the BM3 FlexFuel kit

[Sndmem3s]

Originally Posted by Vantablack

I’m planning to go FlexFuel Stage 1 in my M4. Did you ever figure out what went wrong with your car?

I’m currently on Stage 1 ACN 91 with NGK 97506 plugs gapped to .022. I was planning to get the Bend Calibration filter kit and then the BM3 FlexFuel kit

Yep injector failed

Swapped it out, cleaned the others, gapped my plugs properly (I just got new ones and then got the flex fuel kit impulsively a few weeks later so they were gapped for stock). Car has been running great now on E35-E40ish stage 2 multimap. Logs are clean

Didn’t end up buying the bend filter kit but might do it in the future.

I’d highly recommend flex fuel though. The power difference between pump ACN91 and the 91/93 map on E40 is massive

[Itt]

Originally Posted by Sndmem3s

Yep injector failed

Swapped it out, cleaned the others, gapped my plugs properly (I just got new ones and then got the flex fuel kit impulsively a few weeks later so they were gapped for stock). Car has been running great now on E35-E40ish stage 2 multimap. Logs are clean

Didn’t end up buying the bend filter kit but might do it in the future.

I’d highly recommend flex fuel though. The power difference between pump ACN91 and the 91/93 map on E40 is massive

Did you use an OTS multi-map or a custom tune?
I'm planning to go with an OTS multi-map, but I'm a bit concerned since it increases HPFP pressure to about 3400-3600 psi, while the stock injectors can only handle a maximum of 3000 psi. I'm worried that the injectors might fail in a short time.

[Vantablack]

Originally Posted by Sndmem3s

Yep injector failed

Swapped it out, cleaned the others, gapped my plugs properly (I just got new ones and then got the flex fuel kit impulsively a few weeks later so they were gapped for stock). Car has been running great now on E35-E40ish stage 2 multimap. Logs are clean

Didn’t end up buying the bend filter kit but might do it in the future.

I’d highly recommend flex fuel though. The power difference between pump ACN91 and the 91/93 map on E40 is massive

Which plugs are you currently running and what did you gap them to?