Lean Burn Tuning?

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j91z28d1

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I'm in the 20 percent better mpg at 17.9 to 18.4 to 1. About 50 degrees of timing ...zero detonation and trying to make a smooth primary ve table to cruise at about 40 percent throttle and 18.5 to 1 to reduce pumping losses. My injector duty cycle is definatley lower and I'm still running maf ... I will most likely switch to speed density soon to try it. But as I'm smoothing tables and waiting the couple weeks to payday to fill tank up for hand calculated results...I have 5 year average on this exact rig completely stock so have a good idea. I don't drive much anymore as I moved shop home but gas is near 5.00 again and I revisted this lean burn deal...it does Indeed work and lowers emissions across the board ....fun read is look at what honda did with the insight from 2001 to 2004ish....they ran a commanded afr of 22 -24:1. I have successfully ran the truck at 19 to 1 on my wideband but it tops out there so any afr has to be hand calculated by data logs.


My Ford Fairlane has a turbo 6.0 LS in it and I'm creating a lean burn boosted fuel map for it. I'm looking forward to see the increased efficiency of the turbo incorporated with lean burn. As soon as boost goes over 3 or 4 psi it will flip over to power enriched fuel tables and target 11 to 12.5 to 1 wherever the engine is happy and lower timing.


is this coded into the tune with a separate map? or are you able to turn to target those a:f with the stock tune in close loop? I'm curious of the strategy to make that all work.

the only lean burn I've read about or seen was just steady state cruise at low load. are you able to run this kinda tune the whole time like accelerating thru gears? I read and see guys get away with ****** on a direct injection engines boost on a lean burn. I would never considered trying. very cool

diving down the efficiency rabbit hole, have you thought about trying a cam with a late intake closing grind, especially with the boost. Atkinson cycle I think they call it? seems big in the hybrid world to gain efficiency in the mid range at expense of low end. but boost and a stall to get pasted that?
 

j91z28d1

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My race cars don't live in the trailer between races, they live in my shop. They are carbureted, so I have to live with the smell.IMO, the smell of 100LL avgas and C15 = Good, e85 and unleaded gasolines = Bad.

Last time I bought C15 it was $82 for a 5 gal can. Avgas is running about $5.50/gal here at our local country airports today. I ran 100LL avgas in my dragster instead of e85. I buy 100LL regularly and have for 40+ yrs. I run it in all my lawn care equipment and my ole 2 stroke golf cart. It starts lead fouling the lower spark plugs on my airplane engine (Lycombing o320/160hp) after about 30 hrs. Takes about 10 yrs on my lawncare engines.

See my avatar? That's my 1170 hp, 605 ci bbc, C15 burning Top Sportsman drag car. Used < 1/2 gal of C15 per run. Pictured below is my rear engine dragster (for our daughter) with 10to1 compression 572 ci bbc that I had planned to run on e85, but ran 100LL instead.
View attachment 397663
View attachment 397665
View attachment 397666
Our dragstrip closed so I sold everything and bought a bone stock low mileage 02 C5 Corvette coupe. I'm not gonna hot rod it.


that's a very nice line up.. it's been forever since I've been to a drag strip, it's shame they are closing and feels bad that don't make time to support our local one. sadly since moving here few years ago I haven't made it out to even watch a test and tune. used to be a cheap night out 10 to 15 years ago. I was never anywhere near your level thou. just hang out and fun runs with friends

I could see with eazy access to 100LL at the airport, no reason not to run it in just about anything that didn't have a cat on it. seems like I remember the pump at our track down in FL as 11$ a gal forever ago. I don't remember what kinda race gas it was. we only knew leaded and unleaded. 86$ a 5gal is rough but I guess nothing is cheap at that level, so it's all relative.


funny I have friends that load up the 5gal cans of e85 in their back of their hatchbacks to run track days smelling it all the way there. they say they love it. I think it smells better burning than pump 93 if both don't have cats but I've not had a garage full of av gas or c15 to compare it too and they haven't either. maybe they just love it because they don't have anything to compare it too haha.
 

Mechanic prepper

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is this coded into the tune with a separate map? or are you able to turn to target those a:f with the stock tune in close loop? I'm curious of the strategy to make that all work.

the only lean burn I've read about or seen was just steady state cruise at low load. are you able to run this kinda tune the whole time like accelerating thru gears? I read and see guys get away with ****** on a direct injection engines boost on a lean burn. I would never considered trying. very cool

diving down the efficiency rabbit hole, have you thought about trying a cam with a late intake closing grind, especially with the boost. Atkinson cycle I think they call it? seems big in the hybrid world to gain efficiency in the mid range at expense of low end. but boost and a stall to get pasted that?
It's code in all of our pcms...well at least the p01 and p59....Holden is a gm subsidiary and the Australians use lean burn...I am using HP tuners and changed my platform from gmt to a "V" platform. That is what Australians are...so when you change to the v and write entire the next boot up the pcm does a checksum check and sees Australian use.. there was very little out there on using and those who did complained of cruise control loss....I did loose cruise control until I changed my options menu...

Anyways long story short yes you can accelerate through gears in lean burn...it's quite the learning process to say the least. Although the resolution is very good there is just very little info on set up of ramp in and ramp out rates. One wrong move and it will detonate itself to death so be careful...the detonation generally occures right in the 14.5 to 15.5 afr....peak burn temp is in 14 to 15:1 area...once you get past that and get into 16s and 17s the detonation goes away...so I have found it to be necessary to ramp in fast ... I am in begining part of figuring this all out. It's a pain in ass because you can't tune in real time....have to go into lean tab and manually tune...
I'll try to screen shot some files and am working on a video as well... Hoping others get the bug and co-op different tuning principles to help everyone out and shorten learning curve.


Also I have ECT delays and also don't let it go lean burn under 25mph...I tow alot so I need the weight moving first. But as soon as I hit 30 and temp gets over 160 you can watch the wideband go right from mid 14 afr to 16, 17 18 and maxed out at 19 on wideband depending on throttle position and map sensor... Anything over 60 percent throttle it goes right back to normal and power enrichment happens.

My data logs are wild to look at. Especially timing table logs and STFT logs....when it's in lean burn STFT stays 0.0. And 02 on truck just go dead and hang around 0.1.

I wish I had more time just to go drive and really figure out the eq ratio tables but I just change one part every time I go anywhere and log it. Also being that gas is 4.50 gallon it's hard to justify just driving for no other reason than to tune....
 

B-train

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It's code in all of our pcms...well at least the p01 and p59....Holden is a gm subsidiary and the Australians use lean burn...I am using HP tuners and changed my platform from gmt to a "V" platform. That is what Australians are...so when you change to the v and write entire the next boot up the pcm does a checksum check and sees Australian use.. there was very little out there on using and those who did complained of cruise control loss....I did loose cruise control until I changed my options menu...

Anyways long story short yes you can accelerate through gears in lean burn...it's quite the learning process to say the least. Although the resolution is very good there is just very little info on set up of ramp in and ramp out rates. One wrong move and it will detonate itself to death so be careful...the detonation generally occures right in the 14.5 to 15.5 afr....peak burn temp is in 14 to 15:1 area...once you get past that and get into 16s and 17s the detonation goes away...so I have found it to be necessary to ramp in fast ... I am in begining part of figuring this all out. It's a pain in ass because you can't tune in real time....have to go into lean tab and manually tune...
I'll try to screen shot some files and am working on a video as well... Hoping others get the bug and co-op different tuning principles to help everyone out and shorten learning curve.


Also I have ECT delays and also don't let it go lean burn under 25mph...I tow alot so I need the weight moving first. But as soon as I hit 30 and temp gets over 160 you can watch the wideband go right from mid 14 afr to 16, 17 18 and maxed out at 19 on wideband depending on throttle position and map sensor... Anything over 60 percent throttle it goes right back to normal and power enrichment happens.

My data logs are wild to look at. Especially timing table logs and STFT logs....when it's in lean burn STFT stays 0.0. And 02 on truck just go dead and hang around 0.1.

I wish I had more time just to go drive and really figure out the eq ratio tables but I just change one part every time I go anywhere and log it. Also being that gas is 4.50 gallon it's hard to justify just driving for no other reason than to tune....
That is cool stuff broseph. I'd love to collaborate, I guess I'd give me a reason to buy some software. What are you using and where are you located?
 

Mechanic prepper

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That is cool stuff broseph. I'd love to collaborate, I guess I'd give me a reason to buy some software. What are you using and where are you located?
I use hotuners , efi live and some other open source platforms. I'm working on using the open source code to tune lean burn but haven't finished yet...I'm in NE Washington state
 

Geotrash

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It's code in all of our pcms...well at least the p01 and p59....Holden is a gm subsidiary and the Australians use lean burn...I am using HP tuners and changed my platform from gmt to a "V" platform. That is what Australians are...so when you change to the v and write entire the next boot up the pcm does a checksum check and sees Australian use.. there was very little out there on using and those who did complained of cruise control loss....I did loose cruise control until I changed my options menu...

Anyways long story short yes you can accelerate through gears in lean burn...it's quite the learning process to say the least. Although the resolution is very good there is just very little info on set up of ramp in and ramp out rates. One wrong move and it will detonate itself to death so be careful...the detonation generally occures right in the 14.5 to 15.5 afr....peak burn temp is in 14 to 15:1 area...once you get past that and get into 16s and 17s the detonation goes away...so I have found it to be necessary to ramp in fast ... I am in begining part of figuring this all out. It's a pain in ass because you can't tune in real time....have to go into lean tab and manually tune...
I'll try to screen shot some files and am working on a video as well... Hoping others get the bug and co-op different tuning principles to help everyone out and shorten learning curve.


Also I have ECT delays and also don't let it go lean burn under 25mph...I tow alot so I need the weight moving first. But as soon as I hit 30 and temp gets over 160 you can watch the wideband go right from mid 14 afr to 16, 17 18 and maxed out at 19 on wideband depending on throttle position and map sensor... Anything over 60 percent throttle it goes right back to normal and power enrichment happens.

My data logs are wild to look at. Especially timing table logs and STFT logs....when it's in lean burn STFT stays 0.0. And 02 on truck just go dead and hang around 0.1.

I wish I had more time just to go drive and really figure out the eq ratio tables but I just change one part every time I go anywhere and log it. Also being that gas is 4.50 gallon it's hard to justify just driving for no other reason than to tune....
Thank you for all of this, Rob. REALLY grateful to have you as a contributor to this forum.

This, specifically has the potential to change the economics of running our gas guzzlers significantly. But it seems we're in our infancy of understanding it well enough as DIYers to make it happen reliably without messing something expensive up. There would likely be a big market out there for a reliable lean burn "kit" for these trucks.

Back in the mid 90s there was a group of pilots and engineers out of Oklahoma who figured out that running aircraft piston engines lean not only worked well, it had huge benefits to engine cleanliness and longevity. Conventional wisdom to that point had been that you needed to run them rich because the extra fuel would help cool the valves, etc etc. But those guys proved that that was totally false.

They figured it out by using some new (at the time) technology to directly measure internal cylinder pressures throughout the combustion event in a Continental aircraft engine (8.6:1 compression ratio, so detonation wasn't as much of a risk as it is on our engines) on a test stand.

Background information needed: In aircraft piston engines, pilots use exhaust gas temperature (EGT) to determine the optimal mixture setting because it must be periodically adjusted as the aircraft climbs and the air gets thinner. As the pilot adjusts the mixture they look for the EGT to peak (around 1500ºF) and then adjust the mixture accordingly. Well, conventional wisdom had pilots running the mixture at around 50ºF rich of peak (ROP). Turns out that that's very close to where the peak internal cylinder pressures occurred in the test stand engine. Laws of thermodynamics say that more pressure = more heat. So, not only were pilots burning more fuel than necessary, they were actually putting more heat into the cylinders, valves, etc leading to higher failure rates because these engines are air-cooled. Failure in an aircraft engine can have some undesirable consequences. So, instead running them around 100ºF lean of peak EGT kept them running much cooler, on much less fuel, with only a very small penalty in power output.

It gets better. What they also learned is that the engineers back at Pratt & Whitney in the 1920s and 30s knew this already and large piston-engined aircraft like the DC-6 and Lockheed Constellation used lean-of-peak (LOP) operation to make transoceanic flights possible. But that knowledge had been mostly lost by the 1990's.

Anyway, all of this is to say that running a piston engine lean for better fuel economy has a long and glorious history. I don't know why car companies don't do it more today but my guess is it has something to do with the inherent conflicts between fuel economy and emissions regulations in the US and EU. The Aussies apparently took a more pragmatic approach.
 

j91z28d1

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It's code in all of our pcms...well at least the p01 and p59....Holden is a gm subsidiary and the Australians use lean burn...I am using HP tuners and changed my platform from gmt to a "V" platform. That is what Australians are...so when you change to the v and write entire the next boot up the pcm does a checksum check and sees Australian use.. there was very little out there on using and those who did complained of cruise control loss....I did loose cruise control until I changed my options menu...

Anyways long story short yes you can accelerate through gears in lean burn...it's quite the learning process to say the least. Although the resolution is very good there is just very little info on set up of ramp in and ramp out rates. One wrong move and it will detonate itself to death so be careful...the detonation generally occures right in the 14.5 to 15.5 afr....peak burn temp is in 14 to 15:1 area...once you get past that and get into 16s and 17s the detonation goes away...so I have found it to be necessary to ramp in fast ... I am in begining part of figuring this all out. It's a pain in ass because you can't tune in real time....have to go into lean tab and manually tune...
I'll try to screen shot some files and am working on a video as well... Hoping others get the bug and co-op different tuning principles to help everyone out and shorten learning curve.


Also I have ECT delays and also don't let it go lean burn under 25mph...I tow alot so I need the weight moving first. But as soon as I hit 30 and temp gets over 160 you can watch the wideband go right from mid 14 afr to 16, 17 18 and maxed out at 19 on wideband depending on throttle position and map sensor... Anything over 60 percent throttle it goes right back to normal and power enrichment happens.

My data logs are wild to look at. Especially timing table logs and STFT logs....when it's in lean burn STFT stays 0.0. And 02 on truck just go dead and hang around 0.1.

I wish I had more time just to go drive and really figure out the eq ratio tables but I just change one part every time I go anywhere and log it. Also being that gas is 4.50 gallon it's hard to justify just driving for no other reason than to tune....


that's cool, do you know if the c6 e38 has the option? I haven't heard if it.

I have 67a unlocked too, but it's already in a hybrid, so I doubt it and wouldn't want to do a full write on that thing lol.


Australia always seems ahead of us on the os mod side. I seem to remember a pcm hacking board back in the day that was always busy with aus stuff. they took a old OBD1 gm ecm and make it run map 3bar with all kinds of custom patches.. thing sounded like it was a stand alone by the time they were done.


I'd definitely watch a video you made about it. link it up when you're done.
 

j91z28d1

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it's been 20 plus years back when I first started reading about diy tuning. seem to remember there was a old guy with the screen name grumpy. he was around when they first started digging thru gm ecm code using email chains, didn't even have messages boards yet. I think the mid to late 80s. but he was a Buick GN guy but visited the other boards. if I'm remembering right, the question about lean cruise came up and they were asking him questions and at what point do you stop, he said watch throttle opening % and oil temps.

didn't mean anything to me at the time, but looking back I think he was meaning at some point when leaning and adding timing your throttle will have to be really open and when you see oil Temps climb back off on how aggressive you are. I don't believe anyone was thinking about using it like above when driving around. just in the short periods on the interstate

no clue if that helps anyone doing this, but they archived all his posts when he passed trying to save some of his lost knowledge. I wanna say he was a retired gm engineer of some sort.
 

Mechanic prepper

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Thank you for all of this, Rob. REALLY grateful to have you as a contributor to this forum.

This, specifically has the potential to change the economics of running our gas guzzlers significantly. But it seems we're in our infancy of understanding it well enough as DIYers to make it happen reliably without messing something expensive up. There would likely be a big market out there for a reliable lean burn "kit" for these trucks.

Back in the mid 90s there was a group of pilots and engineers out of Oklahoma who figured out that running aircraft piston engines lean not only worked well, it had huge benefits to engine cleanliness and longevity. Conventional wisdom to that point had been that you needed to run them rich because the extra fuel would help cool the valves, etc etc. But those guys proved that that was totally false.

They figured it out by using some new (at the time) technology to directly measure internal cylinder pressures throughout the combustion event in a Continental aircraft engine (8.6:1 compression ratio, so detonation wasn't as much of a risk as it is on our engines) on a test stand.

Background information needed: In aircraft piston engines, pilots use exhaust gas temperature (EGT) to determine the optimal mixture setting because it must be periodically adjusted as the aircraft climbs and the air gets thinner. As the pilot adjusts the mixture they look for the EGT to peak (around 1500ºF) and then adjust the mixture accordingly. Well, conventional wisdom had pilots running the mixture at around 50ºF rich of peak (ROP). Turns out that that's very close to where the peak internal cylinder pressures occurred in the test stand engine. Laws of thermodynamics say that more pressure = more heat. So, not only were pilots burning more fuel than necessary, they were actually putting more heat into the cylinders, valves, etc leading to higher failure rates because these engines are air-cooled. Failure in an aircraft engine can have some undesirable consequences. So, instead running them around 100ºF lean of peak EGT kept them running much cooler, on much less fuel, with only a very small penalty in power output.

It gets better. What they also learned is that the engineers back at Pratt & Whitney in the 1920s and 30s knew this already and large piston-engined aircraft like the DC-6 and Lockheed Constellation used lean-of-peak (LOP) operation to make transoceanic flights possible. But that knowledge had been mostly lost by the 1990's.

Anyway, all of this is to say that running a piston engine lean for better fuel economy has a long and glorious history. I don't know why car companies don't do it more today but my guess is it has something to do with the inherent conflicts between fuel economy and emissions regulations in the US and EU. The Aussies apparently took a more pragmatic approach.
Your right on track. Common misconception is running lean equals heat and melted pistons...that's only true at max effort high loads....example. Wide open throttle pulls in a 400hp engine with an afr of 14:1 will result in engine damage.... It's too lean...but technically 14:1 is richer than stoich... It's just too lean for the conditions and power output demands ... So second argument especially in the USA is lean creates higher nox.... Again inherently false and they hyperfocused on that same too lean for conditions aspect... I have emissions testing equipment and lean burn on an LS swapped 64 Fairlane without cats has lower emissions than the engine did as per factory and EPA mandated equipment.

My dad owns a 235 Cherokee and if the plane is cruised as instructed the 540 burns 13 gallons per hour... In LOP it burns 7.5 gallons per hour with lower egt , lower cylinder head pressure and oil stays cleaner. That's what made me start playing with this in the first place...especially working on more throttle blade opening and tuning fuel to limit power....by running throttle open more the engine gains efficiency because pumping losses are much lower so the power needed derived from fuel becomes less because the engine isn't loosing power through trying to draw 540 cucic feet of air through an intake 80 percent closed ... It's very simple to understand and very easy to do on an airplane because of 3 lever carb adjusting ....so I'm basically applying that same concept to a 5.3 LS. I'm making good progress on the siverado because it's drive by cable....my suburban is drive by wire so it adds more tuning into the equation and it's power delivery was very irratic at first. It's not expensive to do but one has to be aware of wideband, egt probes and overall have basic knowledge of what detonation sounds like and looks like on the laptop .. it's a bit of work figuring out what works and what doesn't via atmospheric density and intake air temp but eventually you figure out a parameter set and can program safety's.. it's only been a month and maybe 500 miles on the Silverado but it's sorted out good enough I would let someone borrow it and drive across state without worrying about them watching instruments. That's the goal...get safety figured out and other variables figured out and be able to flash someone's car and not worry about 2atching instruments... Although always a good idea... I have egt in every vehicle I own including my Honda Ridgeline ... It's a good indicator of health... And any turbo rigs get boost guages.. just how I'm wired..lol
 

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