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Author Topic: E85 Tuning Methods  (Read 76686 times)
RaraK
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« on: August 02, 2011, 05:28:31 AM »

For a ME7.5 1.8T:

Current setup is 1000cc LOW impedance injectors, utilizing a Honda resistor box.  Tuned for 93 octane now.

Next step is to tune for E85, hence the large injector's used.

Lets discuss the methods, and ways you should/can go about tuning for E85.



1.  Tune for fuel trim to be ~-20% on 93 octane, ECU may or may not be able to adapt to E85 if you just fill the tank with it.  Use Lemmiwinks to adjust timing additive up 3-4 degrees, and theres a "rough" increase in power(only to be proven via dyno).  And a pseudo "flex fuel" setup without the alcohol sensor.

2.  Adjust fuel trims in the same way above(KRKTE, etc..) to get a legit fuel trim value, and adjust the KFZW's closer to KFZWOP, 20 percent closer in small increments and monitor CF's.  This option would be to run ONLY E85 on this tune, no ability to run 93 gasoline in a proper manner. 


Option one seems like a fair idea, Dont necessarily need to squeeze every last drop of performance out of the E85, as it does carry other benefits other than power(cooler, higher octane to prevent detonation, cleaning, etc...)

Lets discuss, any thoughts to another method?  Tuning logic?
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Matt Danger
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« Reply #1 on: August 02, 2011, 08:52:09 AM »

You can't tune for 100% e85 using the ECU's adaptive channels. The adaptive channels have a range up to ~24.5%, not enough for 100% e85. You can use the adaptive channels to run a mixture of e85 and gasoline but the mixture would fluctuate and you'd have to make constant changes. I did this last fall when experimenting with e85. It gets annoying quickly but is fine if you just want to play around.

Adjusting KRKTE for 100% e85 is ideal. Run your tank almost to empty and fill up with e85, then flash a file with increased KRKTE. I guestimated it by adding .020 and then adjusted based on LTFTs. I think the end result was an increase of .027. Didn't take too long to get it dialed in. KRKTE was the only fueling change I made for e85.

Once I got fuel dialed I incremented the KFZWs in the high load columns. I started with the stock maps and added 10* to the highest load column then ramped the next highest load columns up to match. Logged and increased timing based on FATS. Go by FATS and MBT instead of knock or CFs.

The tune would be meant for e85. If you wanted to switch to 93 you'd want to flash a 93 file. If I'm ever traveling and think I won't be able to find an e85 pump I make sure I have my laptop.
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elRey
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« Reply #2 on: August 02, 2011, 10:26:12 AM »

Logged and increased timing based on FATS. Go by FATS and MBT instead of knock or CFs.

how do you log FATS and/or MBT?

What is FATS?

Thanks,
Rey
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Matt Danger
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« Reply #3 on: August 02, 2011, 11:03:43 AM »

FATS stands for For Advancement Of The S. It's a B5 S4 specific measurement of how long it takes to from 4200 RPM to 6500 RPM in 3rd gear. One of the ways to measure performance.

MBT is minimum timing for best torque. On gasoline a lot of guys tune their timing based off knock voltages and correction factors. e85 is much more resistant to knock so you can't tune timing based on knock voltages or CFs. So you advance timing until torque stops increasing. If I understand it correctly.
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RaraK
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« Reply #4 on: August 02, 2011, 08:00:56 PM »

FATS stands for For Advancement Of The S. It's a B5 S4 specific measurement of how long it takes to from 4200 RPM to 6500 RPM in 3rd gear. One of the ways to measure performance.

MBT is minimum timing for best torque. On gasoline a lot of guys tune their timing based off knock voltages and correction factors. e85 is much more resistant to knock so you can't tune timing based on knock voltages or CFs. So you advance timing until torque stops increasing. If I understand it correctly.

Matt, great info! thats sounds like an ideal method.  10* jump though? i know its e85 that seems to far to begin with, but thats just me being cautious.

That info will really help me out when we get on the dyno, we will be dyno tuning the thing for a few hours(already scheduled) so....sweet!  I will surely post the results we have.  This is scheduled the first week of sept. so dont expect it tomorrow
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vwaudiguy
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« Reply #5 on: August 02, 2011, 08:59:41 PM »

There is a certain tuner that currently has files (flexfuel) that will adapt between straight e85 and whatever octane (91-93) for the MK1 R32 engine. All that is needed are larger injectors (550's or 630's) I have to check. I believe all that's required is an idle warmup and the tune adjusts itself accordingly.
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RaraK
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« Reply #6 on: August 03, 2011, 06:38:10 AM »

Yes, i saw this Smiley  Thats why i posted method 1 above, that is my assumption as to how he does this???
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Matt Danger
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« Reply #7 on: August 03, 2011, 07:19:47 AM »

They might just set KRKTE in the middle and let the ECU adapt back and forth. Not sure if it'd be enough to keep it from throwing a fuel trim code.
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RaraK
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« Reply #8 on: August 03, 2011, 09:41:41 AM »

Yea matt thats exactly the logic i had on option one, would pull a little back or add a little either what way.

Then adjust timing via lemmiwinks. and be done with it.
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Matt Danger
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« Reply #9 on: August 03, 2011, 11:16:51 AM »

Gotcha. IMO having an e85 file and a 93 file is easier. Otherwise you'll be constantly having to log, check LTFTs and tweak with lemmi. Both require a laptop.

This is a scenario where having switchable maps via the cruise control stalk or something would be useful.
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nyet
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« Reply #10 on: August 03, 2011, 11:19:38 AM »

They might just set KRKTE in the middle and let the ECU adapt back and forth. Not sure if it'd be enough to keep it from throwing a fuel trim code.

That, and i wouldn't trust open loop fueling ... speaking of which, do ltfts affect open loop? i forgot.
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buergi
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« Reply #11 on: August 03, 2011, 01:04:54 PM »

Hello,
i regularly use 100% E85 for my everyday used A4 with 150hp ANB engine.
Lemmiwinks helped me to adjust timing 8° earlier and primary fuel trim to +25%
I got issues with P1128 and P1137. So i adjusted idle speed to 850 and secondary fuel trim to 67%. Seems to work without codes at the moment. But the engine stillk feels not as powerful as with E10.

Now i search for the right locations of KRKTE, FRAUMX,FRAUMN, FRAOMX, FRAOMN, KFMIRL, KFPED, KFMIOP, KFZW and MLHFM (to compensate my much too low maf-signal) in my file to make it run perfect with E85 and safe with normal pump gas.

If it was somehow helpful for you i could post a log of some driving on german streets.

Best regards,

Buergi

P.S. i think i got all necessary toys for playing:
-friend with vcds
-cheap french E85 2km from here
-galletto 1260
-spare ECU 4b0906018AL (for safety)
-ebay USB-KKL Interface
what else is missing ?
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Jason
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Breaks everything!


« Reply #12 on: August 03, 2011, 01:28:13 PM »

I don't see how you could make this work well without integrating an octane sensor on the return fuel line.
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lulu2003
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« Reply #13 on: August 03, 2011, 01:56:06 PM »

Ethanol has only 50% of the energy per volume.
using E100 would mean 100% increase of injection volume for the same power.
now there's only 85% ethanol in it and you have advantages with knocking/ignition/EGT.
So what would be the volume advance you need for same power? roughly...in practice.
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jibberjive
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« Reply #14 on: August 03, 2011, 11:05:50 PM »

Good thread, I was going to make one of these eventually.

I'm personally going to do separate E85 and 91 tunes, so I bought a cheap second ECU to put the other tune on and keep in the car for when I need to switch to pump gas on the fly (I bought it to tide me over until someone figures out multiple map switching on 1 ECU).  But after that I bought a cheap Acer Aspire One netbook that I'm going to always keep in the car with flashing software and my different files.  So I'll be able to flash files whenever instead of physically swapping ECU's.

Since I've got a laptop always in the car to flash whichever file, I will likely tweak the E85 tune when the fuel changes for the first time, so then I'll have different files for E70 winter, E85 summer, and whenever else. 

I'm putting an ethanol content analyzer in my car and will likely check the content after  almost every fillup.  I was checking out the ECA from Zeitronix, but it seemed pretty expensive for just a gauge (you still had to go get the actual sensor from a junkyard.)  So what I decided to do instead is buy this small digital o-scope to keep in the glovebox, with which I can accomplish the same thing as the Zeitronix ECA (and then I can use the o-scope for other stuff that I need to when I'm not checking the eth cont Smiley ).  The sensors in the OEM flex fuel vehicles indicate ethanol content and fuel temperature by sending a wave with a certain frequency and pulse width.  The frequency indicates ethanol percentage, such that 50hz=0% ethanol, 150hz=100% Ethanol, and +1hz=+1% eth.  The pulse width determines fuel temp such that 1 millisecond = -40*F and 5 milliseconds = 257*F.  I'll print out calibration charts like this and keep them in the glovebox with the o-scope, to check the stats after filling up.


-Here's a list of the cars to pull the OEM sensors from (new they're $300+, so act like it's just some small sensor):
http://www.zeitronix.com/Products/ECA/ECA.shtml

-Here's the o-scope I bought (I've heard of people going with a cheap $30 DMM from Sears as well):
http://www.seeedstudio.com/depot/dso-quad-4-channel-digital-storage-oscilloscope-p-736.html






Just some insight into how much the ECU does and doesn't adapt, I used to put ~3-3.5 ga of E85 per tank together with my 91 oct, to raise the octane a little bit since I had a tune for 93oct, but only 91 gas available.  I eventually tried to add similar amounts to my stage 1+ B6 1.8t A4, but I because the last time I did it (about 3ga E85 and 16 ga total) I tripped a lean condition run code.  I didn't want to risk damaging the engine, but the ECU can definitely only adapt so much.


Logged and increased timing based on FATS. Go by FATS and MBT instead of knock or CFs.
So you don't worry about being knock limited at all when tuning with E85, eh?  Knock and CF's are still good indicators to make sure the tune is safe though, right? (E85 doesn't affect the knock sensors ability to detect actual knock or anything like that, right?) I'm new-ish to MBT tuning as well, but is MBT boost independent then?

Say one was knock limited on a pump gas tune, then goes E85.  Turns up the injectors and finds MBT. Checks knock/CF's and they're still in check.  Assuming the turbos still have some efficiency to go, then would you up the boost (while keeping lambda in check) until it's knock limited again (assuming that the knock limit comes before the turbo leaves its efficiency range)?

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