E85 Cold start issues- help???
 

Switched over to E85 and have been playing with my cold start tune a lot trying to dial it in but haven't been as successful as I would like to be. I feel like I'm missing something... just not sure what. If the car has pretty much any heat in the combustion chamber, it fires easily. But for the first couple tries when it's been sitting at least 12hours and is below 60* it really struggles to catch and fire. Here's a log at 58* and my current tune. Any help would be greatly appreciated! 1.8, turbo, forged rods, MSPNP2, e85, 1000cc injectors, 300DW fuel pump (IIRC..)

MS2 doesn't have good flex fuel control. Are you tuned for e85 exclusively or are you trying to do a mix of tables?

Tuned for e85 exclusively, not trying to mix for the reason you mentioned.

One of the negatives of using e85 in anything is piss poor cold weather initial start performance.
Flex fuel Chevy trucks don't start very well below 50 degrees on e85.
Below freezing it's even worse...
And this is with a setup that MASSIVE cold weather tuning has been done on. GM tried HARD to make E85 work as well as gasoline and failed.
You are fighting an uphill battle to make initial cold start work.
It's probably as much "this stuff doesn't work well cold" as your tune.
Keeping it in a garage overnight or maybe installing some form of block heating is something that should be looked at.

These problems are COMPOUNDED on Flex fuel vehicles that the customer changes between fuel and e85 in cold weather.
It fires back up fine at the pump and will NOT fire again after the truck cools overnight.
The "normal" fix is to completely clear the tank of e85, add gasoline, and clear the KAM memory.
Now the truck will start again...

I just learned to live with it and know that it’s part of the blessings that come with running E85. I can consistently get 82-83% at a local station and the car just runs so nice on it that I exclusively run that even though the I have the full 93 to E85 tables setup to run anything (pretty sure that’s why they call it flex fuel). The exhaust smell is as good as any glue on the market too.....

Growing up with the old school chokes, I want to pump and pump the gas pedal or pull that non-existent choke lever but I just have to give Montego a some time for that second cup of coffee E85 to get going when she’s cold.

Run e70. There is a reason stations will switch to a winter blend.

that strategy certainly works for me but if someone only has an E85 tune, not so much. Also makes me wince a little bit even thinking about an E85 only tune because one would have to either buy the real expensive stuff in the certified E85 blue cans or have enormous trust in the gas station pump label which is not wise IMHO.

BTW: my partner/builder in crime son is a freshman Buff and on the SAE team. Would enjoy connecting with you sometime soon.

Go Buffs! My alma mater.

Yes I think anything other than flex for a street car is a bad call. We do have a local facebook group where people regularly test at the various stations and report eth content.

Thanks everyone for the thoughts/concerns. MSPNP2 doesn't have great flex fuel control and running CA 91 really limits the potential of the build. So as far as I see it my options are:
1) Exclusive E85
2) 101/91 blend
3) upgrade to MS3 for better flex fuel control

1= inexpensive, runs great once started, but hard to start
2= expensive/PITA
3=Expensive just to get flex option

So with these factors in mind (am I missing anything?) E85 seems the best option. Just hoping to dial the tune in a bit. Any advice regarding the tune is greatly appreciated!

You have to understand that E85 is rarely ever E85 (85%). I have seen stations that have about 60% most every time and only 1 in my area that I normally get 82-83% as I previously posted. I have never actually found a load that was 85%. Without a flex fuel sensor, how will you know what you tuned on and then what is in the 2nd, 3rd, etc. tank?

When we were setting up the maps for 93 and E85, I wasted money on a dyno session because I expected the 2nd jug was at least 80% but it ended up being 62%. The other jug was 93 octane.

I used to run "e85" on a ms2 without a flex sensor. I would just retune after every fillup, a pain in the fucking ass.

MS3 would be better, also because it has cranking pulse taper. Max it out and let it taper fast and it will fire near instantly in the cold. Well, if you give it some gas because the afterstart idle taper is broken. The flex sensor also is stupid slow to respond on startup, slowly tapering from 0% to actual, making me wait 5 seconds or more to get a true reading before starting.

My last trip to the "e85" pump netted me e58, which is still within range of the limits on the label at the pump, 51-83%. I only buy from one station, and it's all over the place no matter the season. There were snow on the ground last time I got gas and it gave me 78%. So I believe trying to log the ethanol content is a fruitless endeavor, the pumps mix the stuff up as you pump it. Who knows how they decide to blend, or when they change it up.

They sell little test tubes, you fill it with water and dump "e85" in and shake to measure the content. Could use one of those. I should test the accuracy of my sensor...

I'd keep it garaged on e85 during the cold weeks in San Miguel if I was on a budget.

I'd upgrade to MS3X as soon as I could afford it however...
It's NOT "just to get flex option".
It's the difference between a home computer built 5 years ago and one built last month.
The newer technology is substantially better at MANY things...

I would not waste money on dyno tuning UNTILL I had upgraded to a MS3X.

My 2 cents...

Thanks all for the thoughts. Still hoping to optimize my cold starts. I feel my tune is pretty conservative so not too concerned with the variations in e85 but I will start testing to see. MS3 seems like the best option moving forward.

What did your google search for miata e85 cold start turn up?

Ok, I will post a few pics from my tune in the next few days. I got other stuff going on right now. If you can't wait, try choking with the idle valve during cranking some, I have touched on this before.

That being said, I live near SF and don't even run antifreeze, coldest I have working is about 33°F. But still, choke with the idle valve, we have the capability.

Have you tried priming multiple times before starting?

I imagine that MS2 has a priming pulse setting, and at KeyOn, that pulse is injected by each injector. With E85, I suspect that you have this set at or near maximum (65mS on MS3 1.4.X)

So: KeyOn / KeyOff (after fuel pump stops) / KeyOn... Then to Start. This gives more fuel in the runners to evaporate. This would be the equivalent of pressing the accelerator multiple times when "setting the choke" on a carbureted engine, causing multiple strokes of the accelerator pump (something that may or may not be part of your life experiences).

The choking Son refers to could also help some of that fuel to evaporate.