Lean Cruise tuning with E10

[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. 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.


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.


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.