LSA Flex Fuel Tuning

[Burntendzz]

Hello All,
-Setup-
2009 g8 gt with LSA
1200cc injectors/ Flex fuel sensor

I'm currently diving into tuning. I'm working with a tuner to finish up my current tune, but unfortunately my confidence is not high. When i got the car back it was SUPER rich (.58 Lambda) with 91 and ran horrible at WOT. I was told I could only run ethanol, which seemed strange since i had a flex fuel sensor and the car ran fine on 91 before. I worked with the tuner and we got the 91 tune somewhat dialed in. I added ethanol yesterday and noticed it was running much leaner with only 38% ethanol content. My concern is when he leaned up the tune for the 91, it affected the fueling for the ethanol as well.

e38pull.hpl
lsag8flex1200cc.hpt
91pull3rdgear.hpl
My question-

With a flex fuel sensor, should the lambda change so drastically when ethanol is added? I was under the assumption it would try to keep similar fueling when ethanol is added, hence flex fuel. On 91 my Lambda is .69@WOT and on just %40 ethanol its .80@WOT. It seems like a big difference. What would cause the delta between 91 and Ethanol? Am I missing something, can you control the ethanol fueling separate from gas fueling?

Any insight is welcome. Thank you.

[Ben Charles]

Lambda will read the same.. if looking at WB on gas scale AFR the reading will be the same on pump or e85 or any blend. Naturally stoich changes in the tune

[GHuggins]

The actual afr should actually be closer - it's just your lambda values will show big changes due to the drastically changing stoichiometric ratio. As for you tune - you can run pump just fine with your setup. The tune isn't horrible, but it's obvious your tuner doesn't understand or realize what ethanol requires timing wise He's adding in 5 to 5.5 degrees in your cruising areas and from the looks of the main timing table it's not because your base timing is too low. This will cause your engine oil to cook due to overheating of pistons. Just reference a stock e85 tune for example... Also you probably going to have some serious stomp "stumbling" issues with the blower and your injection timing. E85 usually likes slightly advanced timing and this can blend better with a pump setting, but yours is still stock going into rpms, so when you stomp it after holding elevated rpms you'll probably notice some stumbling if not possibly even backfiring... Just some things to be looking out for.

You might also want your tuner to at least try to tune your torque model as if left alone you might wind up eating transmissions...

[Burntendzz]

Lambda will read the same.. if looking at WB on gas scale AFR the reading will be the same on pump or e85 or any blend. Naturally stoich changes in the tune

Any ideas on what would cause leaner conditions with ethanol? Even cruising lambda is quite a bit leaner with %38 e than straight 91.

[hjtrbo]

Running flex fuel will show up bad injector data. Just get your tuner to double check injector settings.

Ideally, you would run straight 91 and check fuelling. Then go straight e85 and check fuelling again. If it's good then you can work on the stoich blend transition table to get the blended fuel right. If your fuelling is off then you need to check injector data and go back and forward with the MAF tune a few times.

And take GHiggins advice re virtual torque.

[Burntendzz]

He didnt change any injector data going from the 85lbs to the 1200 cc injectors...

[GHuggins]

Then you need to have the fueling, timing (both fueling and ignition) and torque model reworked.

[Ben Charles]

he didnt change any injector data going from the 85lbs to the 1200 cc injectors...

yikes

[Gustavo]

He did by doubling the Stoich AFR values, I would go with injector data and adjust the multiplier in under "Injector Flow Rate Modifier vs. Battery Voltage"

[Burntendzz]

He did by doubling the Stoich AFR values, I would go with injector data and adjust the multiplier in under "Injector Flow Rate Modifier vs. Battery Voltage"

That is true, but those are the injector settings that were in there when i had my 85lb injectors. I did a compare between the two tune files.

[Gustavo]

I suggest to return the Stoich values back to stock and re-adjust your MAF and timing. Use the below tables:

injc.PNG

multiplier.PNG

All the best,

[Burntendzz]

I suggest to return the Stoich values back to stock and re-adjust your MAF and timing. Use the below tables:

injc.PNG

multiplier.PNG

All the best,

Thanks Gustavo, is this technique better than doubling stoich?

[GHuggins]

Don't forget to populate your e85 mbt tables too. This will go further to saving your tranny.

Gustavo's way should work - honestly never done it that way cause I was taught the other way to begin with and I was thinking that some OS's didn't allow that particular table to work kind of like how individual injector controls don't work in some, but having stoic stock would allow you to more finely tune it. I honestly may try the volts table on the next one...

[Gustavo]

Thanks Gustavo, is this technique better than doubling stoich?

Yes sir, doubling Stoich will alter so many other fueling and airflow tables which will make it a hassle for you.

Keep an eye on the cylinder airmass values tho, they may get changed.

[07GTS]

double stoich and halve IFR equal each other out so no change to the air model only the fuel model which is accounted for by each adjustment only the fuel usage is affected which can also be corrected for, if u just double stoich ur asking for alot of trouble to work out

[Burntendzz]

Does anyone think the difference in the e85 and 91 lambda could be fuel pressure? Are there any ways to tell without hooking up a manual fuel pressure gauge(injector duty cycle?)? Would wrong injector data cause this? Its a dual 450 setup, but im wondering if the other pump isnt coming on when it should? Everyone i've shown it to is stumped..

[07GTS]

what ever u scale make sure it mathematically works out to what ur doing, are u using the stock fuel pressure sensor ? or is that all gone now with fuel system

[Burntendzz]

I was able to get the injector data from the manufacturer. It is completely wrong in the tune, from what they sent me.

[07GTS]

if u are using the factory fuel pressure sensor then set the proper data in, if u arnt using it then u have to set the data up to suit the rail pressure u are using

[Burntendzz]

if u are using the factory fuel pressure sensor then set the proper data in, if u arnt using it then u have to set the data up to suit the rail pressure u are using

Stock rails/regulator. The pulse width, flow vs pressure, and offset are all way off from the manufacture specs. Or do these settings not matter as much as i think they do?