Lean Cruise tuning with E10

[Always2Slow]

Have searched far and wide looking for more information regarding this topic and it seems most people are not concerned with getting the most out of their combination in regards to torque, horsepower, and economy. My findings seem strange on the results i have been seeing while trying to get more miles per tank out of the motor. Its winter time so the mpg of gas goes down with the season so I am taking that into consideration. Right now i am around .82 EQR or 1.18 lambda or 17.1 AFR while lightly accelerating or cruising with e10. I have been using the method of lowest map to try to achieve the lowest map possible in my cruise areas and have been up to 64 degrees of timing with minimal gains. Does anyone know what the theoretical AFR value for maximum efficiency or lowest map is for e10 and were your results close to this value?

[EagleMark]

Just trying to find AFR at Stoich seems to be an impossible task! In all my searching I have found numbers from 13.8 to 14.3? Maybe this is do to different levels of ethanol in fuels from state to state or even seasonal gas? The closest to accurate came from GMPP with info on there crate engines at 13.8. Seems the rule of thumb here is 14.22 as found originally by ShawnWeatherMan with fuel he tested and I think everyone has stuck to that or 14.22 is a good halfway point between gas and E10?

But I went looking through my logsserialil LC-1 wide band) from last August to present, we have no known fuel changes here seaon to season. Pumps are marked "May contain UP to 10% Ethanol" My log results have been consistent 13.9 AFR 1.0 Lambda.

By setting my B3601
"The air-fuel ratio (AFR) considered to be stoichiometric.
This value is used by the PCM to determine the AFR of EQ ratio 1.0."
To 13.9 and retuning, I've lost all fluctuating fuel trims and always have the same .84 Lambda reading in PE. Been the best adjustment I've made, everything else falls into place easily now. Lamba WB reading on gauge is predictable as well.

I'm at the same point as you, don't know what is a safe number to shoot for? Hope this turns into a good Lean Cruise thread.

I'm still just starting this and using stock holden Lean Cruise B3639 table AFR/Lambda fluctuates so much do to the variation in table but seems to go .89-.90 EQR which shows 15.84 AFR in data. These are not calculated, just data observations.

Couple questions to add, what is the reasoning for such a fluctuating lean cruise EQ in the stock holden lean cruise? I'm guessing emmissions? I've been running a steady AFR of 16.2 in older TBI truck for years with no ill effects or CAT issues. Still pondering smoothing this table to start for a steady lean cruise result. Lambda is just all over the place with these stock settings.

Is there a reason the first colomn used in Decel is set to 0.00? I loose all lean cruise in decel on freeway until DFCO kicks in...

[RevGTO]

These are good questions, because I'm getting set to do a CALC.VET tune, but several years ago the legislature removed the requirement that the ethanol content be posted on the pump, and now you don't know what you're getting. Supposedly the biggest retailer is supplying E10, but how do you set stoich for your tune if you don't know what gas you're getting?

I ran an LC tune for a while, but my cruise AFR tended to vary quite a bit, and it scared me, so I went back to conventional.

[EagleMark]

There are E test kits. But if you have serial wide band and use the EXT.WO2LAM1 and EXT.WO2AFR1 the AFR is for fuel is shown. Serial data is accurate without seting up controller...

If you look at the stock Lean Cruise B3639 table you'll see why it varies, don't watch AFR, use Lambda! Lambda is always the same for each fuel, AFR can be worlds apart depending on gauge and how controller is set up.

My gauge is now Lambda and stays about .99, when it enters Lean Cruise it ranges 1.01 to 1.13, PE is .84. Way to easy after JoeCar talked me into it!

[EagleMark]

Where's joecar?

What's a safe Lambda for Lean Cruise? 1.0 is Stoich, .84 is like 12.5 AFR for gas but I think 11.7x for E10... what's the math eqaution? I've run 16.2 AFR on gas for Lean Cruise a long time, but have no idea how to convert that to Lambda now that my Stoich is 13.9?

OK I'll try
16.2 AFR / Stoich of 13.9 = 1.165 Lambda?
If that is correct what is math for EQ ?

[joecar]

EXT.WO2AFR1 is based on the stoich AFR programmed into the wideband...


e.g. LC-1 factory default has stoich 14.7; it can be user programmed to say 14.2, in which case it reports the AFR based on stoich 14.2, this is what EXT.WO2AFR1 reports.


Not all widebands allow the stoich AFR to be reprogrammed.

[joecar]

LC is safe at lambda 1.10.

PE requires lambda 0.86.


But, the PCM still needs to know the stoich AFR of the fuel it is using, this is parameter B3601... so if you run E10 you set B3601 to something in the range 13.8-14.3...


the alcohol test kits come with a chart showing stoich AFR for gasoline with various percentages of alcohol.

[joecar]

Once you set B3601 to the value your test kit says, then you do all your tuning in lambda.

[joecar]

...
OK I'll try
16.2 AFR / Stoich of 13.9 = 1.165 Lambda?
If that is correct what is math for EQ ?

AFR = stoichAFR * Lambda = stoichAFR / EQR

Lambda = AFR / stoichAFR = 1 / EQR

EQR = 1 / Lambda



example 1 (PE with stoich 14.2): 0.86 lambda = 12.21 / 14.2 = 1 / 1.163 EQR
example 2 (PE with stoich 13.8): 0.86 lambda = 11.87 / 13.8 = 1 / 1.163 EQR

( notice PE lambda is always 0.86 and PE EQR is always 1.163 )

[EagleMark]

Life is so much easier with Lambda!

Just have to retrian or unlearn my old brain of bad AFR habits.