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! :good:

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

[Always2Slow]

Well not quite some of the replies i was expecting and was really wondering the answer to this question. What is the maximum efficiency AFR for e10. In a few of the tuning books i began to read it said maximum efficiency for gas was like 15.4 to like 15.8 or something like that but the correlation of my logs are supporting my map readings go lower with a leaner AFR. This is a copy of my lean cruise table to give you guys some ideas how far i have taken this, so you can compare and maybe we can find some more evidence on where e10 likes to be at.14539 Here is my table i have been tweaking it but kind of afraid of how far to take this after reading on how people can lean an engine out and get no pinging or knock and the bearings vibrate and cause premature failure to the engine and its components. I can say for the most part the car runs great and you can feel it when lean crusie kicks in as i have my timer set at 10 seconds which is usually 3rd gear for me from a stop. I have been playing with the timing so far and it seems like 35ish is the sweet spot or there about going to start really fine tuning each cell as i go.

[joecar]

Sorry for hijacking your thread.

[EagleMark]

Wasn't your fault joe, I asked for information needed so we could do this. You provided the answers.


Well not quite some of the replies i was expecting and was really wondering the answer to this question. What is the maximum efficiency AFR for e10. In a few of the tuning books i began to read it said maximum efficiency for gas was like 15.4 to like 15.8 or something like that but the correlation of my logs are supporting my map readings go lower with a leaner AFR. Without that conversation, questions and joes answers we could not figure this out. But now we can.

Like you said maximum effecincy of Gas is 15.4 to 15.8. I can give 2 examples of that, both of which I have already proven wrong and GM knew it was wrong back in the 80's when their EFI cars had Lean Cruise, max on those was 16.1 With long time fuel milage testing I ended up at 16.2 so at this point we're splitting hairs...

One is from Wikipidea which shows the 15.4 = 1.05 Lambda.
14540

The other of 15.8 is what the stock Holden tune will do. 15.8 / Stoich of fuel 13.9 = 1.136 Lambda.

Joe has given us a SAFE Lean Cruise Lambda reading earlier of 1.10, notice I asked for SAFE, not optimal or max possible, his answer was within .036 of what a stock Holden tune has shown me at MAX, that tune is never in a constant state in Lean Cruise, it flucuates. So as always his answers once again are sound!

Know we all know how and why. Joe once again has given an example of why none of this should be based on AFR, except of course 2 things, one is B3601 needs an AFR to start and two we are taking AFR data from days of all gasoline and using it as a baseline to convert to E10.

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 )

[Always2Slow]

Wasn't your fault joe, I asked for information needed so we could do this. You provided the answers.

Without that conversation, questions and joes answers we could not figure this out. But now we can.

Like you said maximum effecincy of Gas is 15.4 to 15.8. I can give 2 examples of that, both of which I have already proven wrong and GM knew it was wrong back in the 80's when their EFI cars had Lean Cruise, max on those was 16.1 With long time fuel milage testing I ended up at 16.2 so at this point we're splitting hairs...

One is from Wikipidea which shows the 15.4 = 1.05 Lambda.
14540

The other of 15.8 is what the stock Holden tune will do. 15.8 / Stoich of fuel 13.9 = 1.136 Lambda.

Joe has given us a SE Lean Cruise Lambda ding ea 1.10, notice I asked for SAFE, not optimal or max possible, his answer was within .036 of what a stock Holden tune has shown me at MAX, that tune is never in a constant state in Lean Cruise, it flucuates. So as always his answers once again are sound!

Know we all know how and why. Joe once again has given an example of why none of this should be based on AFR, except of course 2 things, one is B3601 needs an AFR to start and two we are taking AFR data from days of all gasoline and using it as a baseline to convert to E10.

I'm not worried about the hijack and to further explain some of the data I collected I had a good jump of map going from 15.8 to about 17. I wouldnt call 5 to 7 map splitting hairs quite yet . timing on the other hand is a lot less of a difference.
P

[EagleMark]

5 to 7 MAP increase from just the leaner AFR? No spark? That would be a good thing. I'm only to a point in my tune to start working on the lean cruise end, MAP was going to be a major data point.

Off topic but MPG related, I put a fiberglass tonnoeu cover on my truck and picked up 5 MAP at freeway speeds. Less air drag...

[Always2Slow]

You want to lose Map not gain it. Myth busters had an episode on truck covers and the best one or the best for mpg was remove the back gate and put an air gate.

[EagleMark]

Yes correct I should have said lowered MAP. When I said picked up, I meant it went right way.

I did the tailgate down trick back in 1987 when I bought the first Chevy Truck with TBI. Tailgate down was worth 1.2 MPG.

[RevGTO]

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.
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.Yep, I can set my LM-1, B3601, and calc.pids to match and then tune accordingly. I guess I should get an alcohol test kit and then try to fill up at the same station for consistency. My guess is that most of the gas around here is E-10, but it's not posted and you don't really know. Down in OK, there are stations that advertise no ethanol in their gas. But in KS, it's anybody's guess and may even vary by the truckload.

[Always2Slow]

Yes correct I should have said lowered MAP. When I said picked up, I meant it went right way.

I did the tailgate down trick back in 1987 when I bought the first Chevy Truck with TBI. Tailgate down was worth 1.2 MPG.

Not tailgate down but tailgate off with a cargo strap they call it like it like an air gate.