100% E85 woes, maxing STFT @ 1.55 scalar and going lean - HALP!!

[Dfv2]

So this is something alarming, hope you guys can chime in. Looks like fueling is hitting a ceiling, and once (something) hits this ceiling my STFT goes straight for the moon leading to a scary lean condition .

FBO no meth, straight E85 (Mobil class I summer blend), scalar at 1.55%, 78 degrees F. I started at 1.4 and worked up, bailing at 1.55 because I didn't see this getting any better. I ran 40% E85 on the pre-scalar maps quite successfully (under the 34% cap) so this is a new issue. Unfortunately I did not log any fuel pressure or fuel related parameters other than STFT/LTFT and lambdas for bank 1 and 2.



Here's how my main fuel tables are setup, am I triggering something strange with the richer AFR at 4500 RPM? Note that this is where STFT skyrockets...


Finally, the attachment is a zip of the map I'm running (IJE0S) and the raw CSV. I appreciate any insight you may have as to what I've done wrong. Assuming there's a larger issue here, I don't want others to just pop in a scalar of 1.4 off the cobb helpfile, fill with E85 and go to town.

[Dfv2]

Tinkering around a bit, am I bumping into the "fuel floor (min cat protection mode)"?- the AFR's appear to correlate, kinda, to the cat protection table..? I'm lost gents :/

[JoshBoody]

This maybe what the capacity limit looks like... loss of pressure and spiking STFT trying to add fuel. Supposedly it takes little bit before low pressure code is triggered. Did your lower % mixes produce steady STFT... how about no scalar? Guess I have to download another ATR now to see your map. Can you attach the log also?

[Dfv2]

Log is with the map in the zip I attached, please do have a look.

40% E85 mixes before the scalar produced STFT spiking to around 30% and descending steadily. Never issues with that. I am definitely triggering something specific here, no codes are stored by the DME so far.

[///Mangler]

What are your IDC %'s?

T

[lulz_m3]

Try upping the base fuel pressure?

[JoshBoody]

I think you are maxed... if anything lowering fuel pressure may help due to reduced resistance (fluid dynamics hurts my brain though). You could always run a little leaner, lower boost, or mix in the dreaded gasoline. Actually adding gas and keeping everything unchanged (maybe lower timing slightly) would be a safe experiment to see if it is fuel ceiling.

[dzenno@PTF]

Erased what I said earlier. Just opened your map and noticed you forgot to set the Fuel Floor as rich as your Fuel map wants to hit at high load. Not sure that's what's causing this BUT it should definitely be set lower than what you have right now (12) given your fuel map (11.8).

From ATP's help file:

Fuel Floor (Min Cat Protection Mode) - Fuel floor when Fuel Mode = 6.
Tuning Tips – Set this value close to requested fuel at high load high RPM in “fuel main” to keep fueling
close during mode 6 events.

It would be worth while to see if you went into fuel mode 6.

[Terry@BMS]

Log fuel pressure to start.

[Dfv2]

Erased what I said earlier. Just opened your map and noticed you forgot to set the Fuel Floor as rich as your Fuel map wants to hit at high load.

It would be worth while to see if you went into fuel mode 6.

I was in fuel mode 2 each run. I set the fuel floor to 11.75 after also realizing this and still triggered the STFT spike. No codes, same fuel mode.

Log fuel pressure to start.

Will do, I'll log every fuel related parameter available. I'm pretty wary about the AFR's during these even with bailing out quickly, I've blown more than a couple motors in my day, none this expensive to replace though.

[Dfv2]

UPDATE: Fuel Logging



That's a higher load than I've ever run before. Strange throttle closure and timing pull, then the lean condition. Fuel pressure takes a nice dive for no apparent reason (to me)...

I backed it down to a 50:50 mix, changed ONLY the scalar from 1.55 to 1.24, and all is well with the world:



Does anyone have any insight as to what the fuel pressure dive behavior indicates on the first log? At this point I'm just curious, as I'm able to run all the timing I want at stock turbo boost on a 50:50 mix, trouble free.

[dzenno@PTF]

To me it looks like LPFP is unable to meet the requested target which also causes the actual on the HPFP pressure to drop below requested.

Why the heck aren't you getting any codes when that happens??

No matter what goes on at the HPFP, the LPFP should always be around 72psi and its obviously dropping WAY below requested

[Dfv2]

No clue why I haven't popped a code! So the second log there, you're saying that the LPFP actual is always supposed to be 72psi? On that run, I see STFT settling nicely (proper scale), lambas are nailed, IPW is steady. If you were tuning this vehicle would anything else in the second log alarm you?

[Dfv2]

BTW, I mapped out each table and connected interacting tables to one another - Looks about identical to this:



Kidding of course, rep to those that enjoy a good sunny in philadelphia now and then!

[Terry@BMS]

The low pressure pump probably can't handle the volume.

[dzenno@PTF]

No clue why I haven't popped a code! So the second log there, you're saying that the LPFP actual is always supposed to be 72psi? On that run, I see STFT settling nicely (proper scale), lambas are nailed, IPW is steady. If you were tuning this vehicle would anything else in the second log alarm you?

LPFP should always be around 72psi (5bar) +/- 10psi max under normal operatimg conditions.

Hit up Shiv for his upgraded LPFP

[rooringhusky]

BTW, I mapped out each table and connected interacting tables to one another - Looks about identical to this:

http://www.60-130.com/images/im...unnycobb-1.png

Kidding of course, rep to those that enjoy a good sunny in philadelphia now and then!

Lol great picture! Repped...I enjoy your humor

The low pressure pump probably can't handle the volume.

BMS LPFP upgrade soooooon!?

No I'm kidding...but Suscribed bc soon I'll be able to hopefully help or at least learn from this thread...Jake is working with me for a few E85 maps and we might eventually run into similar problems..

I will be 60% E85 map / 91 octane map testing tonight and then moving forward with caution!!

[dzenno@PTF]

Should've really taken your time with it and upped a mix bit by bit.

Can you run the stock tune or any lower power stage with 100%?

[Dfv2]

Should've really taken your time with it and upped a mix bit by bit.

Same applies to every girl I've dated, just can't help myself.

Can you run the stock tune or any lower power stage with 100%?

I'd only be assuming if I said yes. I lowered fuel mass required to hit lambdas by mixing in 93 octane, same load same map (different scalar) and everything is kosher aside from the LPFP looking taxed as you pointed out.

[JoshBoody]

Both logs have dropping pressure... I wonder if it has to do with the PWM driver (no idea what I'm saying currently). Can you log LP voltage? I remember if you unplug LP sensor, it runs at full voltage... that would be an interesting experiment. I've never logged low pressure, or seen others so no idea what's typical at WOT.

[Q4P]

I have to commend you for being the first to experiment with 100% E85 and I certainly wish that the results were slightly more positive. I hope that it's something you did and not the N54 that is causing these issues... nothing against you, I just want to see great success for 100% ethanol on the N54. I will keep checking back in and hope this gets solved... I certainly hope we didn't hit a first true definitive limitation...

[654]

We would need to hack the fuel pump control unit that checks the current draw and pump speed. Or how about a bigger pump that behaves similarly in current draw and pump speed but just provides more flow and then flash the fueling down as in reality the engine would get more fuel than what the DME believes because of the larger pump.

[Carl Morris]

Both logs have dropping pressure... I wonder if it has to do with the PWM driver (no idea what I'm saying currently). Can you log LP voltage? I remember if you unplug LP sensor, it runs at full voltage... that would be an interesting experiment. I've never logged low pressure, or seen others so no idea what's typical at WOT.

Good point. That reminds me, when I first got the car at the beginning of the year and first put a Cobb on it I was seeing much lower LPFP pressures than expected. I wasn't making much power so it never caused the problem seen here. Eventually it did throw a code and eventually they did replace the sensor and it's been working fine on the same LPFP since then.

[Terry@BMS]

Both logs have dropping pressure... I wonder if it has to do with the PWM driver (no idea what I'm saying currently). Can you log LP voltage? I remember if you unplug LP sensor, it runs at full voltage... that would be an interesting experiment. I've never logged low pressure, or seen others so no idea what's typical at WOT.

Not likely, the DME is smart enough to run 100% duty cycle when low pressure is under target. It's a simple PID system. I suspect a boost-a-pump or in tank solution would help here. Although, it may just be a case of his pump needing to be replaced, needing a new filter, ethanol somehow hurting a seal causing an internal pressure leak, etc.

[AR Design II]

figured i would give you props on BB as well as e90post! Still great work excited to see what happens with this in the future!