Lean Burn Tuning?

[swathdiver]

anyways... I don't believe lean cruise would do much for our trucks with the crazy bad aero. the engine load is to high at 70mph to run truly lean. you might get 15:1 out of it, but to run 16-17:1 on today's e10 87 octane crap fuel, you'd need very very low load, a lot of timing and maybe even egr which don't think anything since the first Gen ls1s in the late 90s had?

Tune it for lean cruise and 91 or 93 then. Bet it would run even better.

 

[donjetman]

Tune it for lean cruise and 91 or 93 then. Bet it would run even better.

or e85, or a mix thereof

 

[swathdiver]

or e85, or a mix thereof

Even better!

 

[B-train]

I remember the 7730 ecm running $8D in the 90-92 camaro and firebirds had a complete lean burn written into the bin. just wasn't activated. story was told gm wrote it, it worked well but epa said nope it could damage the emissions system (cat) so it was clicked off.

once accessed it was a easy bit to flip and turn on. I've seen it in action. it worked flawlessly.. get up above the set rpm, and below the load point. it would go to 16:1 airfuel and like 60deg timing. Calc mpg would jump from 25 to 30. and once every 10 sec or so it would flip back to 14.7 to service the cat and check its math since it only had a narrow band o2 factory. I had a wide band installed so could watch it work. was seamless, couldn't feel a thing as it flipped back and forth.


that was such a good driving code for it's time. I just struggled horriblly tuning hot restarts with it, since it didn't use intake air temp but manifold temp plus time air spent in the intake. I moved on to a different code that was easier to tune, os from the sy/ty guys did a crazy amount of mods to but didn't have lean burn on it. always missed it. years later someone else went thru the bin file on a hex level and realized they had missed an inverse sign in the code making it even more difficult to tune the manifold air temp conversation correctly. always wished I still had the car and setup to retest it after that.

ahh the fun times following along with the smart people defining and hacking the obd1 ecm's. it's a shame nothing is being done with the newer gm stuff. just pay the company and take what you get.

a buddy is into the vw world. those guys are still doing wonderful things with the new cars. fully defined ecm, able to add patches to the code for new fiction and even have their bcm defined and mapped to make changes to how the abs and traction control works around corners. all lost in the democratic world of omg don't mod anything in the bcm or you'll kill us all. lol.


anyways... I don't believe lean cruise would do much for our trucks with the crazy bad aero. the engine load is to high at 70mph to run truly lean. you might get 15:1 out of it, but to run 16-17:1 on today's e10 87 octane crap fuel, you'd need very very low load, a lot of timing and maybe even egr which don't think anything since the first Gen ls1s in the late 90s had?

if you could patch these ecm's to run a wideband, you could probably tune it a bit leaner at like 30mph low load cruise around town.

Excellent writeup. Thank you for sharing that. There is a YouTube of a Chicago guy that tuned his LS1 corvette for lean burn using speed density tuning mode. He did a 100 mile road trip or so and calculated his results by hand - 40mpg I believe was his average.

I do agree that the trucks would be harder nowadays, but they do run so rich to keep the cats hot, that I'm sure there's room for improvement.

Case-in-point: I've been farting around with my beater 2008 Denali and have found that running mostly E-85 (50/50 to 70/30) blend with 87 fuel achieves me and octane of about 93-95. The 6.2L has higher compression, and absolutely LOVES it. More so than 93 non-ethanol fuel.

I occasionally get check engine lights for bank 1 and 2 running too lean. I'm good with this because it actually means it is leaner due to it not being calibrated for flex fuel. With the higher octane level, a light foot, and a scanner I can see the spark 45 -53 degrees BTC. Pretty neat and a programming computer would be fun to work with and tweak things.

Fuel economy with this is around 13.5 - 14.5 mixed driving. Used to be a about 14.5 - 16 on 87. The added power and pep is worth the decrease in mpg. Plus, it's cheaper than premium all around - mathed it out. Plus it smells good

 

[donjetman]

See post#1 here in this thread for the yt video of the Chicago C5 vette.

I occasionally run a 20-30% premium/e85 mix in our non-flex fuel 07 6.2L Denali without issue. I drive conservatively, mostly hwy, and I'm getting 18+ mpg.

I hate the smell of e85. I was gonna run e85 in one of my drag cars but changed my mind when I found out how it stunk my shop up. I went with avgas instead. I like the smell of avgas and/or VP c-15 racing fuel.

 

[B-train]

See post#1 here in this thread for the yt video of the Chicago C5 vette.

I occasionally run a 20-30% premium/e85 mix in our non-flex fuel 07 6.2L Denali without issue. I drive conservatively, mostly hwy, and I'm getting 18+ mpg.

I hate the smell of e85. I was gonna run e85 in one of my drag cars but changed my mind when I found out how it stunk my shop up. I went with avgas instead. I like the smell of avgas and/or VP c-15 racing fuel.

That's cool. I did run a tank of premium no ethanol recently and the mileage wasn't impressive. I'm sure a tank or 2 more would've readjusted the fuel trims better. When I got to 1/4 tank I filled up with e85 (approx 75% blend). It ran awesome, but the check engine light came on.

If I run about a 50% blend with 87, no check engine lights and it runs well. I might try what you mentioned and see if anything improves. It's fun to experiment.

If I still worked at AVL POWETRAIN I could probably get my hands on some good tuning stuff. If I was independently wealthy, I'd hire a dyno cell and see what is really possible to achieve. The EPA really kills true engineering for efficiency. Plus, most of the population isn't mechanically inclined, so they have to tune for that variable. Which stinks

 

[j91z28d1]

what ecm is in that truck? have you looked into hptuners or efi live? you'd have to look it up, but some gm ecm's can pretty easily run ethanol sensor and have the tables already in them, just gotta add the sensor and enable it. yours might be one. if you have e85 local and drive often, it would pay for itself.

even if not, you can adjust for it some to not set codes. at least to the point you run out of injector. if you're going to play around with it without tuning, have something to keep an eye on short term and long term trims. as long as you're part throttle not in PE enrichment mode, your trims should add some fuel. been years but I believe even your narrow band o2's still target stoich for whatever fuel they see. they don't what it is.

I only run e85 thru mine stuff right now as a cleaner.. I've seen it clean up the top of pistons better than any cleaner. I'm with you, especially if you don't have cats. it smells much better. I've gotten so sick of smelling like gas fumes I've put cats back on everything. even my motorcycle. I swapped the exhaust on it years ago and tossed the stock with cat in the attic. few years back I put it back on.. was tired of the noise and the smell.

be careful if you find some av gas, most of it says low lead but its low lead for av gas. it's really high for the car world. if you do have cats, it's said to plug them up pretty quickly.

have guys with the 6.2 that wants 93 tried lowering the timing to run 87? wasn't a big deal when it was 30 cents more, but now it's a dollar more. kinda annoying if you don't drive it hard enough to notice a few extra hp.

even my ls3 c6 it's annoying to need 93 for highway trips, I was going to copy the low octane map into the high octane map and flash it for my next trip run 87 and then flash it back. when I got there. but I ended up trailering instead.
I was looking for a 6.2, kinda happy I found this 6.0 instead that seems perfectly happy daily and towing on 87.

 

[j91z28d1]

See post#1 here in this thread for the yt video of the Chicago C5 vette.

I occasionally run a 20-30% premium/e85 mix in our non-flex fuel 07 6.2L Denali without issue. I drive conservatively, mostly hwy, and I'm getting 18+ mpg.

I hate the smell of e85. I was gonna run e85 in one of my drag cars but changed my mind when I found out how it stunk my shop up. I went with avgas instead. I like the smell of avgas and/or VP c-15 racing fuel.

you're literally the first person I've ever heard say they didn't like the smell of e over gas.

what's c-15 up to these days? I haven't seen a race gas pump in years, since gas prices went nuts. used to be a 100 octane unleaded on the way out to the races. had a buddy check a few months back and it was long gone. turned into a non e pump showing 90 octain now.

man how times have changed

 

[Mechanic prepper]

I remember the 7730 ecm running $8D in the 90-92 camaro and firebirds had a complete lean burn written into the bin. just wasn't activated. story was told gm wrote it, it worked well but epa said nope it could damage the emissions system (cat) so it was clicked off.

once accessed it was a easy bit to flip and turn on. I've seen it in action. it worked flawlessly.. get up above the set rpm, and below the load point. it would go to 16:1 airfuel and like 60deg timing. Calc mpg would jump from 25 to 30. and once every 10 sec or so it would flip back to 14.7 to service the cat and check its math since it only had a narrow band o2 factory. I had a wide band installed so could watch it work. was seamless, couldn't feel a thing as it flipped back and forth.


that was such a good driving code for it's time. I just struggled horriblly tuning hot restarts with it, since it didn't use intake air temp but manifold temp plus time air spent in the intake. I moved on to a different code that was easier to tune, os from the sy/ty guys did a crazy amount of mods to but didn't have lean burn on it. always missed it. years later someone else went thru the bin file on a hex level and realized they had missed an inverse sign in the code making it even more difficult to tune the manifold air temp conversation correctly. always wished I still had the car and setup to retest it after that.

ahh the fun times following along with the smart people defining and hacking the obd1 ecm's. it's a shame nothing is being done with the newer gm stuff. just pay the company and take what you get.

a buddy is into the vw world. those guys are still doing wonderful things with the new cars. fully defined ecm, able to add patches to the code for new fiction and even have their bcm defined and mapped to make changes to how the abs and traction control works around corners. all lost in the democratic world of omg don't mod anything in the bcm or you'll kill us all. lol.


anyways... I don't believe lean cruise would do much for our trucks with the crazy bad aero. the engine load is to high at 70mph to run truly lean. you might get 15:1 out of it, but to run 16-17:1 on today's e10 87 octane crap fuel, you'd need very very low load, a lot of timing and maybe even egr which don't think anything since the first Gen ls1s in the late 90s had?

if you could patch these ecm's to run a wideband, you could probably tune it a bit leaner at like 30mph low load cruise around town.

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.

 

[donjetman]

you're literally the first person I've ever heard say they didn't like the smell of e over gas.

what's c-15 up to these days? I haven't seen a race gas pump in years, since gas prices went nuts. used to be a 100 octane unleaded on the way out to the races. had a buddy check a few months back and it was long gone. turned into a non e pump showing 90 octain now.

man how times have changed

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.



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.