lean tuning for mileage?? anyone try it or know anything about it?
01-26-2008, 01:41 PM
#1
lean tuning for mileage?? anyone try it or know anything about it? looking for ideas, links, experiences.
i have wanted to mess with some lean tuning for awhile now. on the engines i have tuned on it seems like you dont see or hear a miss till you get somewhere above 15.5-1. sometimes as high as 17-1.
from what i understand the bigest reason most oem tunes are set at 14.7 is because that gives the best emisions. going leaner increases nitrogen or something like that. not sure of the negative effects of that.
soo, i am thinking about using a lc1 on my daily driver, bmw 528i. i plan on using the programable output to goto the factory ecm. i should be able to tweek the chart on the lc1 to get the factory ecm to target any a/f ratio i choose. it will think it is shooting for 14.7 but it will really be leaner. i may not be able to get the control i want with just the lc1, might need to slap an emspro/squirt on there.
will the egt's go up as i lean it out. do i need to worry about them knowing that i will only be leting it go lean at lite throttle?
how will the cats handle the leaner a/f ratio. cats seem to be fragile and i am wondering if i should remove them, not worried about them one way or the other so i will probably try it and see if they melt down for some reason.
has anyone actualy heard of an improvement in mileage by lean tuning?
i have wanted to mess with some lean tuning for awhile now. on the engines i have tuned on it seems like you dont see or hear a miss till you get somewhere above 15.5-1. sometimes as high as 17-1.
from what i understand the bigest reason most oem tunes are set at 14.7 is because that gives the best emisions. going leaner increases nitrogen or something like that. not sure of the negative effects of that.
soo, i am thinking about using a lc1 on my daily driver, bmw 528i. i plan on using the programable output to goto the factory ecm. i should be able to tweek the chart on the lc1 to get the factory ecm to target any a/f ratio i choose. it will think it is shooting for 14.7 but it will really be leaner. i may not be able to get the control i want with just the lc1, might need to slap an emspro/squirt on there.
will the egt's go up as i lean it out. do i need to worry about them knowing that i will only be leting it go lean at lite throttle?
how will the cats handle the leaner a/f ratio. cats seem to be fragile and i am wondering if i should remove them, not worried about them one way or the other so i will probably try it and see if they melt down for some reason.
has anyone actualy heard of an improvement in mileage by lean tuning?
01-26-2008, 03:41 PM
#2
You will definatly gain only because of a simple rule. If you are commanding less than 14.7 to be used then the car is just going to be putting in less fuel. "As long as ve is tuned"
The only way to do this is to put 1 Nop jump in the vehicle os and then fix the checksum, or You can just cheat and use efilive custom os3. The Commanded air fuel table in thier custom os would do the same exact thing but alot more simple to set up. Also would be alot more accurate.
The only way to do this is to put 1 Nop jump in the vehicle os and then fix the checksum, or You can just cheat and use efilive custom os3. The Commanded air fuel table in thier custom os would do the same exact thing but alot more simple to set up. Also would be alot more accurate.
01-26-2008, 03:42 PM
#3
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Haven't tried leaning it out, cause without using a COS and keeping it out of closed loop in the cruise areas, the O2s are just gonna bring it back to 14.7. However, I have spent some time on my truck and found some mpg in the cruise range using timing... how much it will take depends on the gas used. I run mid grade and picked up 2 to 3 mpg over what it was stock with timing. Have done the same on some other trucks. To see the gains though, you have to keep your foot out of it on the highway (i.e. keep steady cruise speeds). That's the hard part for me... I get impatient and wanna floor it and pass everything in front of me lol 
01-26-2008, 07:50 PM
#5
it wont be open loop. the lc1 wideband has a programable output. the factory setting has the output match a narrow band sensor but you can change that chart to scew it one way or the other.
it will think it is targeting 14.7 or .49volts(whatever it is) but it will really be whatever i want it to be. at wot open loop it should goto factory tuning.
it will think it is targeting 14.7 or .49volts(whatever it is) but it will really be whatever i want it to be. at wot open loop it should goto factory tuning.
01-26-2008, 08:33 PM
#6
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If you push your O2 thresholds down you will bend the
true closed loop AFR. I don't know if you can get to as
high as you'd like or how consistent it will be. If the WB
stays reliable then it could do what you want. But the
filtering lag etc. may destabilize the loop too, may need
to mess with some of the delays etc. that compensate
for sensor lags. And what will you do with the bank that
doesn't have the WB->NBsim in it?
Look at where the "bottoming voltage" of your narrowbands
is, over a broad range of driving, and set your O2 switchpoints
to maybe 100mV above the highest "bottom" voltage. Read
that, +150mV, +200mV... at idle and at highway cruise, see
how much "bend" you get and if there's a point you like. If
you want to spend the time logging and correlating to the
Airflow Mode bins you should be able to dial in a lean(er)
closed loop.
true closed loop AFR. I don't know if you can get to as
high as you'd like or how consistent it will be. If the WB
stays reliable then it could do what you want. But the
filtering lag etc. may destabilize the loop too, may need
to mess with some of the delays etc. that compensate
for sensor lags. And what will you do with the bank that
doesn't have the WB->NBsim in it?
Look at where the "bottoming voltage" of your narrowbands
is, over a broad range of driving, and set your O2 switchpoints
to maybe 100mV above the highest "bottom" voltage. Read
that, +150mV, +200mV... at idle and at highway cruise, see
how much "bend" you get and if there's a point you like. If
you want to spend the time logging and correlating to the
Airflow Mode bins you should be able to dial in a lean(er)
closed loop.
Last edited by jimmyblue; 01-27-2008 at 01:19 AM.
01-27-2008, 12:01 AM
#7
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Having the AFR adjust automatically to something leaner is not what the engine wants. To do it correctly it takes a lot of work in the VE. When you add any amount of load the engine isn't going to like a lean AFR and it will require more throttle which defeats the purpose you are going for. You have to work the VE between areas of load transitions in your normal driving range.
It will take a while to get a feel for what the engine will take.
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01-27-2008, 05:28 AM
#8
I've been running lean cruise for over 3 years. Depending on which cam I've had in there, up to 4mpg difference was had. Still running cats also.
I'm back to a mild EdC 220/224 cam and I can run it leaner than the last cam. Still playing with it but I'm back up to 15.9-16.1. With the GT2-3 cam, I could run 16.7 and got over 30mpg on the tank. Which is pretty darn good for a heavy pig like the GTO.
The '04 GTO is the only car that can enable lean cruise though over here.
I'm back to a mild EdC 220/224 cam and I can run it leaner than the last cam. Still playing with it but I'm back up to 15.9-16.1. With the GT2-3 cam, I could run 16.7 and got over 30mpg on the tank. Which is pretty darn good for a heavy pig like the GTO.
The '04 GTO is the only car that can enable lean cruise though over here.
08-22-2010, 03:24 PM
#10
If you push your O2 thresholds down you will bend the
true closed loop AFR. I don't know if you can get to as
high as you'd like or how consistent it will be. If the WB
stays reliable then it could do what you want. But the
filtering lag etc. may destabilize the loop too, may need
to mess with some of the delays etc. that compensate
for sensor lags. And what will you do with the bank that
doesn't have the WB->NBsim in it?
Look at where the "bottoming voltage" of your narrowbands
is, over a broad range of driving, and set your O2 switchpoints
to maybe 100mV above the highest "bottom" voltage. Read
that, +150mV, +200mV... at idle and at highway cruise, see
how much "bend" you get and if there's a point you like. If
you want to spend the time logging and correlating to the
Airflow Mode bins you should be able to dial in a lean(er)
closed loop.
true closed loop AFR. I don't know if you can get to as
high as you'd like or how consistent it will be. If the WB
stays reliable then it could do what you want. But the
filtering lag etc. may destabilize the loop too, may need
to mess with some of the delays etc. that compensate
for sensor lags. And what will you do with the bank that
doesn't have the WB->NBsim in it?
Look at where the "bottoming voltage" of your narrowbands
is, over a broad range of driving, and set your O2 switchpoints
to maybe 100mV above the highest "bottom" voltage. Read
that, +150mV, +200mV... at idle and at highway cruise, see
how much "bend" you get and if there's a point you like. If
you want to spend the time logging and correlating to the
Airflow Mode bins you should be able to dial in a lean(er)
closed loop.
I am fine tuning my tune now and am trying to get my STFT's
in line with the wide band and maybe lean the tune out a bit
as the exhaust smells rich to me, have you refined this or
can you add anything to what you wrote above? My o2's
switch from ~100 to ~900...I thought that is what they are
supposed to do when working correctly?
Also what are the "Airflow Modes"? ie. what do the 0-16 refer to?
08-22-2010, 05:45 PM
#11
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What you smell / interpret as "rich" is probably a hydrocarbon
smell. Slightly rich produces mostly CO which is odorless. HC
comes up as you move away from stoich in either direction.
A hydrocarbon smell that also stings, is definitely lean (HC
+ NOx).
I haven't played much with this in a while. Last time I was
messing with the blower truck, we started at the factory
500mV and were seeing 13.5:1 or so for idle AFR. Moving
to the F-body setting of 350mV brought it to about 15:1
and that's where we left it.
Airflow Mode is a set of "bins" that lump ranges of actual
airflow into an index. There is an airflow mode vs airflow
table that sets that up. As far as I know there is no other
use for airflow mode than indexing the O2 switchpoint table
(could be wrong, though). So similarly to rejiggering the FTCs
for more resolution where you need it, you could alter how
the airflow mode bins are set up, favoring resolution from
idle to cruise (where heat will tend to alter the O2 sensors'
behavior vs real AFR).
You'd have to grab a bunch of data and make sense of it
to do a real fine job, but you could go at it more simply,
try 300mV and see what you get out the pipe, 250mV, ....
You would probably end up having to refit the spark table
after you pick a happy (repeatable, at least) AFR point.
smell. Slightly rich produces mostly CO which is odorless. HC
comes up as you move away from stoich in either direction.
A hydrocarbon smell that also stings, is definitely lean (HC
+ NOx).
I haven't played much with this in a while. Last time I was
messing with the blower truck, we started at the factory
500mV and were seeing 13.5:1 or so for idle AFR. Moving
to the F-body setting of 350mV brought it to about 15:1
and that's where we left it.
Airflow Mode is a set of "bins" that lump ranges of actual
airflow into an index. There is an airflow mode vs airflow
table that sets that up. As far as I know there is no other
use for airflow mode than indexing the O2 switchpoint table
(could be wrong, though). So similarly to rejiggering the FTCs
for more resolution where you need it, you could alter how
the airflow mode bins are set up, favoring resolution from
idle to cruise (where heat will tend to alter the O2 sensors'
behavior vs real AFR).
You'd have to grab a bunch of data and make sense of it
to do a real fine job, but you could go at it more simply,
try 300mV and see what you get out the pipe, 250mV, ....
You would probably end up having to refit the spark table
after you pick a happy (repeatable, at least) AFR point.
08-22-2010, 09:25 PM
#12
What you smell / interpret as "rich" is probably a hydrocarbon
smell. Slightly rich produces mostly CO which is odorless. HC
comes up as you move away from stoich in either direction.
A hydrocarbon smell that also stings, is definitely lean (HC
+ NOx).
I haven't played much with this in a while. Last time I was
messing with the blower truck, we started at the factory
500mV and were seeing 13.5:1 or so for idle AFR. Moving
to the F-body setting of 350mV brought it to about 15:1
and that's where we left it.
Airflow Mode is a set of "bins" that lump ranges of actual
airflow into an index. There is an airflow mode vs airflow
table that sets that up. As far as I know there is no other
use for airflow mode than indexing the O2 switchpoint table
(could be wrong, though). So similarly to rejiggering the FTCs
for more resolution where you need it, you could alter how
the airflow mode bins are set up, favoring resolution from
idle to cruise (where heat will tend to alter the O2 sensors'
behavior vs real AFR).
You'd have to grab a bunch of data and make sense of it
to do a real fine job, but you could go at it more simply,
try 300mV and see what you get out the pipe, 250mV, ....
You would probably end up having to refit the spark table
after you pick a happy (repeatable, at least) AFR point.
smell. Slightly rich produces mostly CO which is odorless. HC
comes up as you move away from stoich in either direction.
A hydrocarbon smell that also stings, is definitely lean (HC
+ NOx).
I haven't played much with this in a while. Last time I was
messing with the blower truck, we started at the factory
500mV and were seeing 13.5:1 or so for idle AFR. Moving
to the F-body setting of 350mV brought it to about 15:1
and that's where we left it.
Airflow Mode is a set of "bins" that lump ranges of actual
airflow into an index. There is an airflow mode vs airflow
table that sets that up. As far as I know there is no other
use for airflow mode than indexing the O2 switchpoint table
(could be wrong, though). So similarly to rejiggering the FTCs
for more resolution where you need it, you could alter how
the airflow mode bins are set up, favoring resolution from
idle to cruise (where heat will tend to alter the O2 sensors'
behavior vs real AFR).
You'd have to grab a bunch of data and make sense of it
to do a real fine job, but you could go at it more simply,
try 300mV and see what you get out the pipe, 250mV, ....
You would probably end up having to refit the spark table
after you pick a happy (repeatable, at least) AFR point.
(correct or not) that makes sense to me...but...
So here goes...I understand part of what you wrote...
Do you know what the 0, 2, 4,...etc "airflow mode" cells/range refer to?
Are they groups of airflow from lowest to highest? ie. does the higher
the mode/cell number = more airflow? Are the last 2 allocated for WOT?
Which table in HPT is the "airflow vs airflow table? does this need adjustment or is stock correct or close enough?
Shouldn't I set this table up after setting up the VE and MAF with a WB
And then make the trims (percent of error) approximately align with the WB
by adjusting the o2 values?
Thanks
08-23-2010, 06:20 AM
#13
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I've been running lean cruise for over 3 years. Depending on which cam I've had in there, up to 4mpg difference was had. Still running cats also.
I'm back to a mild EdC 220/224 cam and I can run it leaner than the last cam. Still playing with it but I'm back up to 15.9-16.1. With the GT2-3 cam, I could run 16.7 and got over 30mpg on the tank. Which is pretty darn good for a heavy pig like the GTO.
The '04 GTO is the only car that can enable lean cruise though over here.
I'm back to a mild EdC 220/224 cam and I can run it leaner than the last cam. Still playing with it but I'm back up to 15.9-16.1. With the GT2-3 cam, I could run 16.7 and got over 30mpg on the tank. Which is pretty darn good for a heavy pig like the GTO.
The '04 GTO is the only car that can enable lean cruise though over here.
08-23-2010, 08:08 AM
#14
I run all mine lean. Tuning them, I lean them out as much as I can that doesnt start to increase coolant temps. My Nova ran real lean, high 16ish:1 but my TA Im guessing doesnt have as efficient of a cooling system (a lot less air flow under hood) and needed more fuel to keep temps down, it runs warmer so I dropped it down to 15:1 and then it was better. I would say for what they are they get really good gas mileage.... better than factory.
08-24-2010, 05:35 AM
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I run all mine lean. Tuning them, I lean them out as much as I can that doesnt start to increase coolant temps. My Nova ran real lean, high 16ish:1 but my TA Im guessing doesnt have as efficient of a cooling system (a lot less air flow under hood) and needed more fuel to keep temps down, it runs warmer so I dropped it down to 15:1 and then it was better. I would say for what they are they get really good gas mileage.... better than factory.
Right, good luck with that.
09-23-2010, 10:18 PM
#16
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Wow... I was just thinking about this today. I've read about so many 04 GTO owners with lean cruise enabled getting 30+mpg highway (even A4's) that I was wondering how much an LS1 Fbody is capable of. Has anyone tried a lean cruised stock internal Fbody? The Fbodys are lighter than the Goats an I'm sure reasonably close in aero so should be capable of better MPG yes?
So EFILive can implement a lean cruise mode for any LS1 car?
So EFILive can implement a lean cruise mode for any LS1 car?
09-24-2010, 02:57 AM
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Wow... I was just thinking about this today. I've read about so many 04 GTO owners with lean cruise enabled getting 30+mpg highway (even A4's) that I was wondering how much an LS1 Fbody is capable of. Has anyone tried a lean cruised stock internal Fbody? The Fbodys are lighter than the Goats an I'm sure reasonably close in aero so should be capable of better MPG yes?
So EFILive can implement a lean cruise mode for any LS1 car?
So EFILive can implement a lean cruise mode for any LS1 car?
05-05-2011, 09:09 AM
#18
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I hate to bring up a old post, but with efi live is all u have to do is enable the lean cruise mode? I have hp tuners which I know cant do it, but hated to buy efi live and not be able to figure out how to do it.
05-05-2011, 09:53 AM
#19
To get lean cruise mode, you have to have a compatible patch for your OS.
Then, you have to read the entire tune to EFI live, apply the patch, configure the lean cruise parameters, then write entire back in.
Here is a list of patches that I have, there may be more available. Just some slight tinkering on my Yukon gave me an average 2MPG increase.
Then, you have to read the entire tune to EFI live, apply the patch, configure the lean cruise parameters, then write entire back in.
Here is a list of patches that I have, there may be more available. Just some slight tinkering on my Yukon gave me an average 2MPG increase.
05-05-2011, 12:26 PM
#20
I'm also curious about the lean cruise with efilive. I already have efilive and have tuned with it some to get more familiar, but how do i go about getting the lean cruise part enabled? is there a tutorial or instructions on how to get it setup? i would really like to try this on my pickups 5.3l first to see if i can get any gain from it.