Fuel Economy Tuning Ideas

[6.0 van]

I have lean cruise in my US controllers. Tuned and enabled lean cruise on several P01s and P59s now. Trade secret. My Express van runs open loop idle, closed loop off-idle and in lean cruise at highway speeds. That one is actually a mexican based GMT800 L31 350 tune though.

holy old post!
can anyone expand on this?

[Billf6531]

Lean cruise is available on Australian ECUs - Holden Commadore, etc. North American ECUs have it disabled. In binary you can remove the jump routine to enable lean cruise.. HPT originally used .bin files which could be edited to enable lean cruise. I no longer have the details of the binary location that required editing, but here's my 2003 C5 binary file with lean cruise enabled. It worked well, however I could achieve similar mileage tweaking the O2 sensor and Mode vs Airflow tables, and running all-MAF, which left the tune in closed loop.

[blindsquirrel]

MAF-only or stock blended or straight speed density is nothing to do with open loop/closed loop.

I found almost 1.5 MPG by just... disabling the MAF altogether. Yes, even after MAF and VE were separately tuned.

[Firebirdmuscle]

I have been working on my truck for a few weeks off and on when i do drive it. I can't seem to get DFCO to enable. I have been trying different entry and exit points to get it to enable. I think I have reached the threshold for my timing tables for my 87 octane. I got into knock going up the couple really steep hills I have on my drive. I also have tried the MPG math's in this thread but it doesn't seem to populate right. I could be making a mistake when configuring them. They seem to spit me numbers from 2-9 which is low. I normally get around 16-18 MPG in the truck.

Can anyone lend a hand on some of this I may be doing wrong and also help with the MPG math. Here is my latest file and logs from yesterday. Thanks for any help and guidance.

Jp Silverado 14.68 5 spark and DFCO and proportional O2.hpt
6-6-22 JP truck drive to work.hpl
6-6-22 JP truck drive home.hpl

[6.0 van]

I have been working on my truck for a few weeks off and on when i do drive it. I can't seem to get DFCO to enable. I have been trying different entry and exit points to get it to enable. I think I have reached the threshold for my timing tables for my 87 octane. I got into knock going up the couple really steep hills I have on my drive. I also have tried the MPG math's in this thread but it doesn't seem to populate right. I could be making a mistake when configuring them. They seem to spit me numbers from 2-9 which is low. I normally get around 16-18 MPG in the truck.

Can anyone lend a hand on some of this I may be doing wrong and also help with the MPG math. Here is my latest file and logs from yesterday. Thanks for any help and guidance.

Jp Silverado 14.68 5 spark and DFCO and proportional O2.hpt
6-6-22 JP truck drive to work.hpl
6-6-22 JP truck drive home.hpl

I've been playing with the same stuff. trying to get into dfco easily. Im having a hard time finding help with dfco if its not for creating "burble tunes".

Disclaimer!! I'm a total noob! take anything I say with a grain of salt.

It looks like some of your settings went the wrong direction.
ex. your entry tps is lower than your logged tps.

this is where im at.. still sneaking up on it a little.

Attachment 121095

watch your log for the spots where pedal position goes to 0%, then look to see if you meet requirements rpm, baro, tps...


question: are you messing with your proportional 02 settings? I'm trying to understand if I need to do that, because mine is stock 6.0.

[6.0 van]

Lean cruise is available on Australian ECUs - Holden Commadore, etc. North American ECUs have it disabled. In binary you can remove the jump routine to enable lean cruise.. HPT originally used .bin files which could be edited to enable lean cruise. I no longer have the details of the binary location that required editing, but here's my 2003 C5 binary file with lean cruise enabled. It worked well, however I could achieve similar mileage tweaking the O2 sensor and Mode vs Airflow tables, and running all-MAF, which left the tune in closed loop.

I'm thinking that the air flow mode method might be best for me, but im still new & trying to self educate on alot of this stuff.

I am not 100% sure about how to target the settings.. it looks like the spot i want to taget (airflow vs. mode) is right in the 15 range. The one cell that is not on the o2 vs airflow table ! Im sure its a simple solution, im just trying to tackle one thing at a time & right now focused on dfco. i'll get to it soon.

1995 van 6.0 dfco 005.hpt

[Firebirdmuscle]

You are correct about the tps. I have since raised those set points where it should be activating it and I’m still not able to get into dfco from what I can tell. My injectors never go below 2.5 ms. I thought I read somewhere they should go to .5 ms. It may have been earlier in this thread.

[6.0 van]

You are correct about the tps. I have since raised those set points where it should be activating it and I?m still not able to get into dfco from what I can tell. My injectors never go below 2.5 ms. I thought I read somewhere they should go to .5 ms. It may have been earlier in this thread.

post your current tune & log.. it took a little screwing around for me to get it going. & yes mine goes tp .1 ms . heres how it looks..

dfco 007.hpl

[Firebirdmuscle]

post your current tune & log.. it took a little screwing around for me to get it going. & yes mine goes tp .1 ms . heres how it looks..

dfco 007.hpl

here was my drive home this morning. the file i am attaching is the one I'm going to try this evening going to work. I adjusted some things to just try to get it to activate. I am adjusting stuff in the direction I think i need to be reading the descriptions of each table but haven't quite found what I'm missing just yet. Fixing to look at your log now. Any idea on the MPG graph not working either?


Will have to download the newest version to be able to look at your file. Ill have to do that tomorrow. Thanks for sharing.

[6.0 van]

here was my drive home this morning. the file i am attaching is the one I'm going to try this evening going to work. I adjusted some things to just try to get it to activate. I am adjusting stuff in the direction I think i need to be reading the descriptions of each table but haven't quite found what I'm missing just yet. Fixing to look at your log now. Any idea on the MPG graph not working either?


Will have to download the newest version to be able to look at your file. Ill have to do that tomorrow. Thanks for sharing.

I dont have the mpg thing working. thats soon..

-your entry rpm is 2k. seems that could come down depending on how easy you want it to activate. 65mph in 4th gear is 1600rpm.
-your enable map might need to come up a bit, & exit with it. I found mine would meet the map requirement & start closing the throttle & push the map back up causing it to immediately exit dfco.

Im not going to suggest anything about dfco spark or airflow because i havent really figured that out yet. Mine still noses over pretty good during dfco & timing goes to 0 deg.
I dont know how to deal with that yet.

just something to try.... remember, im pretty new to this. I appreciate having somebody to help me sort through this.

[6.0 van]

I want to start playing with the airflow mode o2 settings, as described in this thread.

my rich/lean v.s airflow table does not have a 15 column. which seems to be where i spend most of my cruise time. Can i change that ? can i add or edit a column ?

1995 van 6.0 012.hpt

[henny45]

anyone have advice on making a lean tune up to run an hho generator on a 4.8l? at this point all ive done was adjust VE a bit and im going to try an open loop tmrw and pull 10-15% fuel out of it. havent messed with dfco much yet, nor have i added much timing at all. thanks

[Billf6531]

hho?

[HellKnightHicks]

I noticed no MPG gain when leaning out the AFR via the O2 tables mentioned. As well as making DFCO more aggressive.

I did notice in a jeep I was tuning that the DFCO was very agressive from the factory.

[Hondaeater]

I want to start playing with the airflow mode o2 settings, as described in this thread.

my rich/lean v.s airflow table does not have a 15 column. which seems to be where i spend most of my cruise time. Can i change that ? can i add or edit a column ?

1995 van 6.0 012.hpt

You can change where the switch happens in the o2s and get minimum fuel benefit. You need to keep the stoich correct and implement the lean/fuel saving as you have. You should set lean ramp rate to bring in the lean multiplier faster. 0.250. The o2 sensors are getting confused. They are using the stoich target, but the switching is lowered, now you bring in the lean multiplier and they are still trying to hit stoich but switching at the 300 mV. No. Stoich switching same, lean based off that target and if you want a leaner mix then change the multiplier not the o2.
You only want this leaner AFR to enable between 30-35 mph curious? I would broaden MPH let the EQ subtractor be your "range" selector. Set the burst knock back to stock or look at the Corvette file and use those values so it is not so aggressive. Without it you get spark knock and it will start to factor toward the low octane table. Since your hi and lo tables are the same, you have no safety valve. In the area you are leaning out you might want to set that 5-8* lower in the low table AND enable the Burst knock. Burst knock is predictive in that it reduces spark but only in the conditions required. If you only use hi-lo and they are the same, you need to be much more conservative so you do not get knock during those throttle tip in events and conditions that would normally trip the Burst knock. You can log burst knock and see when it is retarding the timing. It will bring the spark back into the hi-lo table when conditions allow but if you have it disabled then the spark table is usually reduced so it doesn't have knock or knock sensors are de-sensitized and that is an overall power change not only when conditions merit the drop in spark for a short moment then get back to main spark.
You are on the right track for sure.
What mods have been done to engine?
I have not upgraded to 5.0. to see yours but I am basing the statements on Firebirdmuscle #289 post.

[Hondaeater]

Billf6531 hho = "Brown gas"... hydrogen generator... uses electrolysis.

[Fast4.7]

You can change where the switch happens in the o2s and get minimum fuel benefit. You need to keep the stoich correct and implement the lean/fuel saving as you have. You should set lean ramp rate to bring in the lean multiplier faster. 0.250. The o2 sensors are getting confused. They are using the stoich target, but the switching is lowered, now you bring in the lean multiplier and they are still trying to hit stoich but switching at the 300 mV. No. Stoich switching same, lean based off that target and if you want a leaner mix then change the multiplier not the o2.
You only want this leaner AFR to enable between 30-35 mph curious? I would broaden MPH let the EQ subtractor be your "range" selector. Set the burst knock back to stock or look at the Corvette file and use those values so it is not so aggressive. Without it you get spark knock and it will start to factor toward the low octane table. Since your hi and lo tables are the same, you have no safety valve. In the area you are leaning out you might want to set that 5-8* lower in the low table AND enable the Burst knock. Burst knock is predictive in that it reduces spark but only in the conditions required. If you only use hi-lo and they are the same, you need to be much more conservative so you do not get knock during those throttle tip in events and conditions that would normally trip the Burst knock. You can log burst knock and see when it is retarding the timing. It will bring the spark back into the hi-lo table when conditions allow but if you have it disabled then the spark table is usually reduced so it doesn't have knock or knock sensors are de-sensitized and that is an overall power change not only when conditions merit the drop in spark for a short moment then get back to main spark.
You are on the right track for sure.
What mods have been done to engine?
I have not upgraded to 5.0. to see yours but I am basing the statements on Firebirdmuscle #289 post.

On the High vs Low octane table. I usually pull about 8 degrees for the low octane table but that is at the highest gm/cyl loading the engine sees. Take my 383 SBC for example. It sees 0.84-0.96 gms/cyl at WOT. Starting at 0.80 gms/cyl to 1.20 I will reduce the low octane table 8 degrees. Then go up to about 0.44 gms/cyl and interpolate between. At light load there is little reason to retard the spark. However at heavy load to prevent detonation as needed the PCMs low octane tables should be lower values than the high octane table. I actually pull 4 degrees in the high octane map at 1.20 gms/cyl and interpolate that between the highest recorded gms/cyl values my engine reads. If the air is extremely dense it provides a safety net to help prevent detonation from the increased cylinder pressure.

Leave the CTS and IAT timing tables alone at high temps. Let the PCM remove the OEM values at high coolant and IAT readings or you are asking for trouble. I also use AFR timing correction as well. It prevents detonation when the engine is working hard in closed loop at a leaner than PE air/fuel ratio.

My last 200 mile highway trip, I did not get over 2,500 rpm or go into PE a single time. I ran most of it with the cruise set between 70 and 78 mph. Pulled several 6-8% grades in overdrive with the torque converter locked. I managed 19.7 mpg in a 6,500 lbs Express van with a 500 hp 383/4L85E and 3.73 gears with LT245/75R16s.

[Fast4.7]

I meant to throw this out there too. Once you get the fueling and timing adjusted to where the engine runs efficiently it will generate much less carbon. My exhaust has gone from jet black like a pre-emissions diesel to so clean it is actually rusting from the condensation of moisture.

20221011_195444.jpg

[bk2life]

This is how I run all my cars since 1998. Open loop is superior in all ways for wideband tuned engines without closed wideband operation.
Narrowband closed loop will drag it back to some unwanted 14.7:1 target which is never a desirable a/f ratio.

thank you for this

[kingtal0n]

thank you for this

Hah. Its just you and me guy, the crazy ones.

I meant to throw this out there too. Once you get the fueling and timing adjusted to where the engine runs efficiently it will generate much less carbon. My exhaust has gone from jet black like a pre-emissions diesel to so clean it is actually rusting from the condensation of moisture.

Alcohol fuels reduce carbon products, hydrocarbon which remain unreacted are rare because of the extremely short C-C-O-H chain. Its hard to form a sticky conglomerate with a single carbon cation.

Running lean on gasoline will reduce carbon products for various reasons. Some because oxygen sensors are averages so when they target around 14.7 some cylinders are 14.5 14.6 and those generate many carbon products which collect on valves, piston, exhaust. It can lead to some cylinder gradually increasing in compression due to carbon buildup over many years, or losing compression due to poor valve sealing for the same buildup reason.
Running lean also reduces the portion of unreacted hydrocarbons in general. Exhaust gas and engine oil can dissolve carbon so over time a reduction in hydrocarbon deposits and more solvated carbons means these fluids may gradually clean up the engine or exhaust. It depends what type of deposits, the harder diamond-like deposits may be difficult to remove with such a mild fluid. The PCV system plays a large role in the removal of unreacted products from the crankcase and is essentially the difference between life and death for an engine over a long term, without powerful PCV suction and a fully sealed crankcase, those hydrocarbon products pollute engine oil and circulate throughout the oil system leaving deposits, which leads to wear and eventual failure.

The info is spread out, I fully support PCV

no evacuation to remove the contaminant laden vapors from the crankcase and this allows them time to settle and mix with the engine oil accelerating wear and eventual failure

https://www.theturboforums.com/info/...rs-101.378656/