How many tuners actually change stoich for the ethnaol based fuels?

[07cobaltsupercharged]

Just curious how many of you guys tuning out there actually change the stoich value table input for using ethanol enhanced fuels such as E10 or do you just leave it at 14.7 and then just adjust the PE table .5 richer to compensate at WOT (I really dont care if im running .5 leaner idle/cruising and only concerned about WOT with the ethanol). I dont really see any difference in changing stoich from 14.7 since computer knows stoich as stoich no matter what the actual mixture is of ethanol.

For instance even though a gauge is showing 14.7 while idle/cruising we know its actually at 14.13 for E10 even though gauge wont read that. But what about WOT? Is whats showing on gauge or in/hptuners afr histogram for WOT correct or is it actually off as well if stoich table input is not changed?

Also, are the stft/ltft corrections being made affected by what value is actually put in the stoich table? I dont think it is but want to make sure.

Ok I hope all that made some sense!~

[Redline MS]

What's the point of tuning if you don't calibrate for the chemistry of the fuel?

Yes you should be changing the stioch point based on the fuel used. Since "most" places are using "up to 10% enthanol" a safe stioch point is about 14.4.

All the more reason to be calibrating in lambda as a lambda of 1 would be equivalant to the set stoich point.

Howard

[KLUG'S SS]

What's the point of tuning if you don't calibrate for the chemistry of the fuel?

Yes you should be changing the stioch point based on the fuel used. Since "most" places are using "up to 10% enthanol" a safe stioch point is about 14.4.

All the more reason to be calibrating in lambda as a lambda of 1 would be equivalant to the set stoich point.

Howard

I agree 100% with these statements! I always change the stoich point to coincide with the fuel that is going in the tank. IMO it's just half ass tuning if you don't change it. I even went out and bought myself an ethanol test kit so I know exact percentages of ethanol at stations in my area and I am sure some people may think that is being a little too technical about it but I dont.

[07cobaltsupercharged]

I just bought a ethanol test kit as well today and will be checking exactly where ethanol % is and changing stoich table accordingly.

My gauge only reads afr, so im kinda stuck with that for now. So I just need to make sure I correct for my gauge reading for the E10 as it will be off when WOT.

I had 11.5 afr WOT in a boosted application when I had 14.68 in the stoich table and then changed table to 14.13 for E10, so this changed my WOT AFR reading to 11.0 which I think is correct and im good to go.

Thanks guys.

[KLUG'S SS]

If you would like you can create a couple of custom PIDs to display Lambda in the scanner instead of AFR.

[Redline MS]

I agree 100% with these statements! I always change the stoich point to coincide with the fuel that is going in the tank. IMO it's just half ass tuning if you don't change it. I even went out and bought myself an ethanol test kit so I know exact percentages of ethanol at stations in my area and I am sure some people may think that is being a little too technical about it but I dont.

What where your findings on ethanol content where you are??

Howard

[HawkZ28]

What kind of differences are you seeing in MPG's in comparison to 14.7 tune with alky free pump gas?

[07cobaltsupercharged]

We have 6 vehicles and every single one of them gets 3-4 worse mpg with the E10. All the cars run noticeable worse as well especially on a warm day. Its corn fuel BS is what it is.

[HawkZ28]

Even tuned for the E10?

Mine, with the stock tune, got about 2-3 mpg worse with 89 (10% alky) vs 87 on the highway.

I agree- ran like BUTT too.

[07cobaltsupercharged]

Even tuned for the E10?

No not tuned, all the other cars are just reg daily drivers for wife and kids and such.

[Gh0st]

You guys do know that changing the stoich in the ECM is pointless if you're using narrowbands right? Sounds like you guys have no idea what the stoich value is used for.

I would recommend you guys do some more research....search this site and a few other forums and read on how closed loop fueling works. There is a lot of valuable information and MANY threads on tuning for E10. Search

[Gh0st]

I just bought a ethanol test kit as well today and will be checking exactly where ethanol % is and changing stoich table accordingly.

My gauge only reads afr, so im kinda stuck with that for now. So I just need to make sure I correct for my gauge reading for the E10 as it will be off when WOT.

I had 11.5 afr WOT in a boosted application when I had 14.68 in the stoich table and then changed table to 14.13 for E10, so this changed my WOT AFR reading to 11.0 which I think is correct and im good to go.

Thanks guys.

Well yeah...PE fueling targets are highly influenced by the stoich value...richening stoich is obviously going to richen PE fueling

[Redline MS]

You guys do know that changing the stoich in the ECM is pointless if you're using narrowbands right? Sounds like you guys have no idea what the stoich value is used for.

I would recommend you guys do some more research....search this site and a few other forums and read on how closed loop fueling works. There is a lot of valuable information and MANY threads on tuning for E10. Search

Please explain......

[07cobaltsupercharged]

Yes I noticed how much better my car runs with MAF open loop with no stft's being used to correct when stoich value was changed in the table for E10. Im tempted to run MAF OL all the time and not use VE table/closed loop any more. Once I go in closed loop I get some surging/hesitation light throttle even though the MAF and VE are dialed in fine so I suspect its the changing of the stoich value and NB's just not working correctly.

[KLUG'S SS]

Everything in closed loop will and should work just fine with the stoich value changed in the tune! I have tuned several cars/trucks in my area with the stoich changed for the e10 around here and they all run perfect in closed loop. You may have something else going on there.

[jimmypop13]

The o2 sensors only read 14.7 as correct regardless of what is entered as the stoich value, right? So changing it would have no effect

[JoeCiv]

You guys do know that changing the stoich in the ECM is pointless if you're using narrowbands right? Sounds like you guys have no idea what the stoich value is used for.

I would recommend you guys do some more research....search this site and a few other forums and read on how closed loop fueling works. There is a lot of valuable information and MANY threads on tuning for E10. Search

???
what?

[JoeCiv]

The o2 sensors only read 14.7 as correct regardless of what is entered as the stoich value, right? So changing it would have no effect

the o2 sensors read lambda 1

doesnt matter if you run gasoline, ethanol, methanol, they still switch at lambda 1...

[07cobaltsupercharged]

Everything in closed loop will and should work just fine with the stoich value changed in the tune! I have tuned several cars/trucks in my area with the stoich changed for the e10 around here and they all run perfect in closed loop. You may have something else going on there.

Yea ive double checked over and over for weeks but the car just runs better in OL vs CL in light throttle conditions. Doesnt really bother me being in CL but its noticeable off slightly going from 1200-2000 rpms. Probably the blower with some turbulence I would guess then.

The o2 switching volts tho are different for 14.13 E10 vs 14.7 straight gas. Ive read many articles that NB's are only accurate at 14.7 and anything else they are not accurate even tho Lambda 1 is for E10 and 14.7 gas.

There are many contradicting articles out there on all this. Sometimes hard to decipher them all and what they exactly mean.

[KLUG'S SS]

Yea ive double checked over and over for weeks but the car just runs better in OL vs CL in light throttle conditions. Doesnt really bother me being in CL but its noticeable off slightly going from 1200-2000 rpms. Probably the blower with some turbulence I would guess then.

The o2 switching volts tho are different for 14.13 E10 vs 14.7 straight gas. Ive read many articles that NB's are only accurate at 14.7 and anything else they are not accurate even tho Lambda 1 is for E10 and 14.7 gas.

There are many contradicting articles out there on all this. Sometimes hard to decipher them all and what they exactly mean.

Any article that states that they are only accurate at around 14.7 afr I feel is a bunch of BS because the narrowbands seem to work and switch just fine on the flex fuel vehicles with e85 in the tank. Just my opinion.