Lean Cruise mode

[94Blazer383]

OK, my truck runs good and has plenty of power, but here lately I have been thinking gas mileage. Right now I have no EGR and I know that can cause the mileage to go down some, so I have been thinking about putting it back on.

I haven't messed with the lean cruise mode very much but I was wondering what all is entailed to make it work correctly. With lean cruise turned on, when is it actually activated when you are driving as far as speed, rpm, etc.... What tables are used to tune it?

Also, how could I make my truck run leaner in closed loop? Lets say I want it to run 15.0:1 instead of 14.7:1 how would I do that? I tried to change the "Stoich AFR for Closed Loop" to 15.0 but my wide band still showed 14.7, so I guess its not that easy.

[94Blazer383]

I think I just answered my own questions. I took a look at the $OD hack.

If you enable lean cruise mode then you use table L4BB4 or "Open Loop AFR vs Coolant Temp vs Vacuum" to change the AFR.

[94Blazer383]

I found this from HaulnA$$ over at thirdgen,

"Yes, there is a lean cruise mode. Some calibrations use it, some don't but it is easily enabled. By enabling the "Open Loop AFR Enable" flag (L400D, bit 0) and ensuring that the min temp setting constant at L48C7 is reasonable, the PCM will use the "Open Loop AFR vs Coolant Temp vs Vacuum" table in closed loop. This table is always used in open loop but by enabling the above parameters, these AFR's will be targeted in closed loop. I have verified this by datalogging desired AFR in place of Batt Volts. BLM's will be affected in closed loop when the desired AFR is above or below stoich. When tuning fuel, this should be taken into consideration to ensure VE table accuracy. When I tune open loop fuel, I disable EGR (and block it off to prevent any valve leakage) as well as CCP and Cat converter overheat protection then bypass the Cat (I run with a gutted one). This cuts the fueling modifiers down to AE and PE. I then set the table values in the operating temp range to something like 13:1 across the board and datalog desired AFR vs WBO2 AFR and adjust the VE accordingly. This ensures that the VE tables represent actual VE and not some fudged value. When I move to closed loop, I disable lean cruise and tune the O2 thresholds for BLM's of 128 across the board knowing that my VE tables are accurate. This is especially helpful when the factory O2 sensor has moved from the factory location. Once thresholds are tuned, I move on to proportional gains to get the O2 voltage swings where they need to be. Once all this is set, I enable and tune lean cruise. Oh yeah, I forgot AE. I tune AE in open loop with the WBO2 as well as WOT AFR".

[94Blazer383]

Anyone running lean cruise????

On the way to work this morning it looked like the truck was still running really close to 14.7 on my wide band. My commanded AFR is around 15.5 while cruising.

[getsideways]

Anyone running lean cruise????

On the way to work this morning it looked like the truck was still running really close to 14.7 on my wide band. My commanded AFR is around 15.5 while cruising.


did you check the bit at l400d? that is needed to be checked. do you have commanded afr in the bat volts feild to verify commanded afr? ive ran that way before and it works just like haulin described. he is the man with this stuff. the temp at location l48c7 should be set te a reasonable temp to enable it. in my bin it was enabled under 150deg celcius. so all the time.

[MSlewis]

I dont know what editor you are running but I dont have lean cruise mode parameter in my BJLH OD bin for tunerpro.If not mistaken the open loop AFR vs temp vs vacuum table is only used in open loop,wich uses temperature enable set by you in the constants.One way I have manipulated AFR in both idle & cruise modes is by changing the o2 swithching voltages @ different airflow rates in the tables.If it is idleing well then just try adjusting it in the mid-to-upper ranges.

If you are trying to reach upwards of 15-16 AFR I dont think it is possible when closed loop is enabled but not 100% positive.

[94Blazer383]

did you check the bit at l400d? that is needed to be checked. do you have commanded afr in the bat volts feild to verify commanded afr? ive ran that way before and it works just like haulin described. he is the man with this stuff. the temp at location l48c7 should be set te a reasonable temp to enable it. in my bin it was enabled under 150deg celcius. so all the time.

Yes L400D is set, and yes I am watching the command AFR at the battery volts. I have L48C7 maxed out to 150 deg C, thats like 304 deg F.

The command AFR shows the the correct AFR value that I have set in the "Open Loop AFR Vs. Coolant Temp. Vs. Vacuum table". But, looking at my wide band I am still staying around 14.7 most of the time.

[94Blazer383]

I dont know what editor you are running but I dont have lean cruise mode parameter in my BJLH OD bin for tunerpro.If not mistaken the open loop AFR vs temp vs vacuum table is only used in open loop,wich uses temperature enable set by you in the constants.One way I have manipulated AFR in both idle & cruise modes is by changing the o2 swithching voltages @ different airflow rates in the tables.If it is idleing well then just try adjusting it in the mid-to-upper ranges.

If you are trying to reach upwards of 15-16 AFR I dont think it is possible when closed loop is enabled but not 100% positive.

If you set bit 0 at L400d it will enable lean cruise mode. Lean cruise mode also uses the open loop AFR vs vacuum table.

[94Blazer383]

I found this .bin at the moates site. It has lean cruise enabled and the temp table at L48C7 set to 150* F, 65* C. Change file from .txt to .bin.

So does this mean that when the truck is hotter that 150* F, 65* C, that it will go out of lean cruise or lean cruise will come on?

[MSlewis]

Interesting, I have no clue, but I looked at 400D & still see no lean cruise in there.I see the open loop AFR table & enabling criteria as it applies to EGR, is reduction accomplished with ecm allowing skewered 02 readings because it knows charge is dilluted?
Also, how do you put commanded AFR into datasream out?

[getsideways]

well, id say your ve table is that far off or you need to adjust your o2 tables to maintain the proper afr? haulin needs to chime in here. he knows this the best.

[94Blazer383]

Interesting, I have no clue, but I looked at 400D & still see no lean cruise in there.I see the open loop AFR table & enabling criteria as it applies to EGR, is reduction accomplished with ecm allowing skewered 02 readings because it knows charge is dilluted?
Also, how do you put commanded AFR into datasream out?

If you are using tuner pro, in the Flag/Switch area you need to add lean cruise or its also called open loop AFR enable, to your .xdf file. It is at 400D bit 0.

This is from th $OD hack....

L400D: FCB $A4 ; MODE WD, AFR 3, 1010 0100
; b7 1 = SINGLE PASS EGR TEST
; b6 1 = VATS
; b5 1 = USE L4780 TBL FOR %EGR
; b4 1 = EGR = 0 AT IDLE
;
; b3 1 = OPN LP FUEL DISABLE EGR
; b2 1 = BACK PRESS EGR
; b1 1 = LINEAR EGR/ 0 = EVRV EGR
; b0 1 = USE OPN LP AFR IF TEMP L.T. L48C7 IN CLOSED LP
: (b0 = 1 FOR TIER 1, USE AFR TBL L4BB0 IF COOL LT 65c)


The desired/commanded AFR variable is at (L026D). The ignition volts variable is at (L00A1). What you want to do is change (L00A1) to (L026D) at address (L520C). If you open the bin with a hex editor you will see the original (00 A1) at (L520C), change this to (02 6D) and the ignition volts display should now be commanded/desired AFR. You will know you have it when at normal operating temperature cruise the value is 14.7. If you cant find it, you can send it to me an I will change it for you.

[94Blazer383]

well, id say your ve table is that far off or you need to adjust your o2 tables to maintain the proper afr? haulin needs to chime in here. he knows this the best.


I dont see how my VE tables could be off, I am staying right at or around 14.7. Also with lean cruise on the BLMs do not change, with lean cruise off I stay very close to 128.

[getsideways]

so you have changed the afr in the Open Loop AFR vs Coolant Temp vs Vacuum table to 15.5 in the cruise areas correct? note that these are vacuum readings not kpa so its the inverse of kpa i believe. acyually if blm's arent updating with lean cruise set, something is wrong. they should update if commanded afr is different than 14.7 according to haulin,s post. it sounds like its not going into lean cruise mode and using the table for its afr.

[Arger]

i am running a dynamic efi setup with leancruise enabled so i cant tell you how to turn it on but i know when it does engage i am light on the throttle and up to temp and cruising speed. Are you looking for it to come on when you are climbing the hills or you on an open hwy? I never really see it come on in the city.

[94Blazer383]

so you have changed the afr in the Open Loop AFR vs Coolant Temp vs Vacuum table to 15.5 in the cruise areas correct? note that these are vacuum readings not kpa so its the inverse of kpa i believe. acyually if blm's arent updating with lean cruise set, something is wrong. they should update if commanded afr is different than 14.7 according to haulin,s post. it sounds like its not going into lean cruise mode and using the table for its afr.


I think this is all going back to the temp table at L48C7. My bin had this table maxed out. The factory AIZX bin I posted had this table set to 65* C, also my Edelbrock MPFI bin had lean cruise enabled and the L48C7 was set to 65* C.

I noticed while emulating if I brought the temp setting in this table down below what the actual temp of the truck was that my BLMs would start to update again. I have a chip burned with the temp lowered to the operating range of the truck, I will see what it does on my way home from work today.

[94Blazer383]

i am running a dynamic efi setup with leancruise enabled so i cant tell you how to turn it on but i know when it does engage i am light on the throttle and up to temp and cruising speed. Are you looking for it to come on when you are climbing the hills or you on an open hwy? I never really see it come on in the city.

open highway.

[MSlewis]

Well I looked for L48C7 in my constants & it is not there. L48C6 is my temp enable, could it be that my xdf is incomplete? Also all the bits that are checked in your 400 code is also checked in mine, although I have EGR turned off.

[93ChevyTBI]

dang...Haulin hasn't chimed in yet?? He must be on vacation or something.

Blazer, what kind of gas mileage are you getting anyway?? Last I heard it was 16 mpg.....that's pretty good with a 383 with 20" wheels. I don't see how it could get much better than that. I'm only getting 12-13 with a 355.

[94Blazer383]

16! if I told you that I was lying! I wish....more like 11-12. That may have been true before I recaled my speedo.

It seems like I use more gas when I am on the expressway running 70-75 mph. I blame that on the 4.10s.

[94Blazer383]

Well I looked for L48C7 in my constants & it is not there. L48C6 is my temp enable, could it be that my xdf is incomplete? Also all the bits that are checked in your 400 code is also checked in mine, although I have EGR turned off.

That is correct but there is also a temp table at 48c7.


L48C6 FCB 56 ; 2c COOL, MIN FOR CLSD LP
;----------------------------------
; SEE OPT WD AT L400D
;
; AFR MD BYTE 3, ($A4 1010 0100)
; b0 1 = USE OPN LP AFR IF TEMP LT L48C7 IN CLOSED LP
;----------------------------------
L48C7 FCB 253 ; 150c, IF COOL L.T. THRESH USE TBL L4BB0
; DURING CLS LP IF b0 SET, L400D
; (Only valid if 400D, b0)
;==============================================


You can add these tables to your xdf file. In the constant/scaler area, right click your mouse, click insert new xdf item, select constant, in the address box type 48c7. Do you have a copy of the $0D hack? Its a must have if you are going to be tuning and adding tables to your xdf file.

[MSlewis]

I do not have that info & was under the assumption the xdf had everything available code-wise already listed. Verifies my knowledge of assumptions!I do use Tunerpro,& think my xdf came from Moates library but not certain.

Not adept with code,addresses,and writing.. but at least having all the info is agreeably crutial to trying to tune.

Pulled up the hack & thought I found the HOLY GRAIL!!! So thats where most of the answers are. Still don't know how to add the missing info to my xdf, it ask for more than just the adrress, & I haven't the slightest.

It appears to me that when enabled, & using the open loop AFR table, the reason BLM doesn't update is because it's probably set above 14.7:1, and the NB 02 is pegged lean & not switching. From what I understand both INT & BLM need a swtching 02 in order to update. If you are @ 128 when its enabled then that is where it will stay untill some condition is met to disable L400D criteria.

[93V8S10]

I do not have that info & was under the assumption the xdf had everything available code-wise already listed. Verifies my knowledge of assumptions!I do use Tunerpro,& think my xdf came from Moates library but not certain.

Not adept with code,addresses,and writing.. but at least having all the info is agreeably crutial to trying to tune.

Pulled up the hack & thought I found the HOLY GRAIL!!! So thats where most of the answers are. Still don't know how to add the missing info to my xdf, it ask for more than just the adrress, & I haven't the slightest.

It appears to me that when enabled, & using the open loop AFR table, the reason BLM doesn't update is because it's probably set above 14.7:1, and the NB 02 is pegged lean & not switching. From what I understand both INT & BLM need a swtching 02 in order to update. If you are @ 128 when its enabled then that is where it will stay untill some condition is met to disable L400D criteria.
I just got TunerPro a few weeks ago. Last week I discovered the Help section. Now I can read the hack! Check it out.:rocking:

[93ChevyTBI]

16! if I told you that I was lying! I wish....more like 11-12. That may have been true before I recaled my speedo.

It seems like I use more gas when I am on the expressway running 70-75 mph. I blame that on the 4.10s.

I thought 16 mpg was hard to believe when you told me especially when we compared your fuel map to mine....yours was close to double. Silly me for believing you j/k

To be totally honest with ya, I think more than 14-15 mpg may be out of your reach. It's damn near physically impossible to get much better with a stroker. I don't know the math on it but that's just my opinion.

Don't blame everything on the 4.10's. Keep in mind you can drive the Cavy to work still and have a bad ass truck to pull your boat with no worries. Like everything else, there are trade offs.

Talked to mechanic today....buying all parts for roller swap this week. I can't wait!!! Only thing left to do is MSD ignition and flowmasters (taking Edlebrocks off.....too much like glass packs). Ohhhhhh....and after that.....seeing the info from desktop dyno...... we WILL line them up :rocking: that stroker should be neutralized... torque from stroker = roller swap. Just don't roller swap on me. j/k

[94Blazer383]

I thought 16 mpg was hard to believe when you told me especially when we compared your fuel map to mine....yours was close to double. Silly me for believing you j/k

To be totally honest with ya, I think more than 14-15 mpg may be out of your reach. It's damn near physically impossible to get much better with a stroker. I don't know the math on it but that's just my opinion.

Don't blame everything on the 4.10's. Keep in mind you can drive the Cavy to work still and have a bad ass truck to pull your boat with no worries. Like everything else, there are trade offs.

Talked to mechanic today....buying all parts for roller swap this week. I can't wait!!! Only thing left to do is MSD ignition and flowmasters (taking Edlebrocks off.....too much like glass packs). Ohhhhhh....and after that.....seeing the info from desktop dyno...... we WILL line them up :rocking: that stroker should be neutralized... torque from stroker = roller swap. Just don't roller swap on me. j/k

If I roller swap I have to build another motor. The block in my truck is the old school non roller block.

[94Blazer383]

It appears to me that when enabled, & using the open loop AFR table, the reason BLM doesn't update is because it's probably set above 14.7:1, and the NB 02 is pegged lean & not switching. From what I understand both INT & BLM need a swtching 02 in order to update. If you are @ 128 when its enabled then that is where it will stay untill some condition is met to disable L400D criteria.

Thats makes sense, thanks.

There really isnt much to making your own tables in tuner pro, If I can figure it out anyone can. You have to play with the conversion math to get the table/scaler to show what you want. I like to convert all my temps over to *F.

[MSlewis]

Did you ever get it to enable & actually have it go to what you set it for AFR wise?

[94Blazer383]

Did you ever get it to enable & actually have it go to what you set it for AFR wise?



No, I got frustrated and put it back the way it was.

What I did do was play with the 02 sensor voltages, and change the Stoich AFR to 15.0. The truck is running a little leaner according to my wide band and stays fairly close to 15.0.

[MSlewis]

I have no egr valve & have the code disabled with the egr/MPH constant. Looking @ the code it appears to me that when what you are calling lean cruise is enabled, egr has to be functional for it to work. When I say functional I mean code wise, not the actual valve itself. I believe the pcm uses the o2 sensor to figure out wether or not the valve physically opened, so if your like me & don't have the valve installed you will also have to disable the egr flag to keep the CEL off.

On the right track with 02 voltages as they are applied in all closed loop calculations & can be tailored to specific airflow ranges, IMO.

Let me know how it turns out.

[94Blazer383]

I have no egr valve & have the code disabled with the egr/MPH constant. Looking @ the code it appears to me that when what you are calling lean cruise is enabled, egr has to be functional for it to work. When I say functional I mean code wise, not the actual valve itself. I believe the pcm uses the o2 sensor to figure out wether or not the valve physically opened, so if your like me & don't have the valve installed you will also have to disable the egr flag to keep the CEL off.

On the right track with 02 voltages as they are applied in all closed loop calculations & can be tailored to specific airflow ranges, IMO.

Let me know how it turns out.


I do not have an EGR either, and yes I do have it disabled. Its funny you mention it though because I have mine sitting on the work bench. I have been thinking about putting it back on, for gas mileage. The only thing is I cant find the solenoid that runs it since I took it off so long ago.

I always wondered how the ECM knew if the valve was working or not since there is only a simple, solenoid, and the valve itself. I guess the 02 sensor would be the only feedback the ECM could have.

[93ChevyTBI]

I've been thinking about this for 3 days and debating whether or not to add this to the thread but what the hell.

Even though I don't know squat about tuning, could it be possible to enable lean cruise with the TC lock up?? That would be when you are cruising and need it. Why couldn't you make whatever enables the lockup to enable lean cruise???

just a thought.....

[MSlewis]

The desired/commanded AFR variable is at (L026D). The ignition volts variable is at (L00A1). What you want to do is change (L00A1) to (L026D) at address (L520C). If you open the bin with a hex editor you will see the original (00 A1) at (L520C), change this to (02 6D) and the ignition volts display should now be commanded/desired AFR. You will know you have it when at normal operating temperature cruise the value is 14.7. If you cant find it, you can send it to me an I will change it for you.

Since we're back on this subject lately I thought I would get back to modifying my bins,editors,and ads files for future use. Even thoughh I have a much better understanding of the hack, I can't seem to find these items (L00A1)&(L026D)in either the hex editor or the hack,did however see (L520C)and its FDB 00A1 reference to what appears to be byte 16 for aldl output. What is it that I'm missing???

[Blue71]

Since we're back on this subject lately I thought I would get back to modifying my bins,editors,and ads files for future use. Even thoughh I have a much better understanding of the hack, I can't seem to find these items (L00A1)&(L026D)in either the hex editor or the hack,did however see (L520C)and its FDB 00A1 reference to what appears to be byte 16 for aldl output. What is it that I'm missing???
026D Its in there, do a find.
Add a constant with the hex address of 520C 16bit (16, BATTERY A/D) apply it, double click the constant change to 26D (AFR)
Command fuel will show up in Batt Volts of tunerPro/DataMaster.

[94Blazer383]

Since we're back on this subject lately I thought I would get back to modifying my bins,editors,and ads files for future use. Even thoughh I have a much better understanding of the hack, I can't seem to find these items (L00A1)&(L026D)in either the hex editor or the hack,did however see (L520C)and its FDB 00A1 reference to what appears to be byte 16 for aldl output. What is it that I'm missing???


http://i105.photobucket.com/albums/m232/tapyz250/desiredafr.gif

[MSlewis]

026D Its in there, do a find.
Add a constant with the hex address of 520C 16bit (16, BATTERY A/D) apply it, double click the constant change to 26D (AFR)
Command fuel will show up in Batt Volts of tunerPro/DataMaster.

Ahhh...I see, well sort of. The hack I'm using doesn't have descriptions of whats at those addresses, so where do you find that info, different version of the hack??? Thats one of the issues I've noticed, depends on where the hack came from,who wrote it,is it correct,complete, etc,etc.

I would've thought that was a function, not a constant.What differentiates the two? Anyway, I'd like to put the AFR into where the Des Gov TPS is since we dont use that anyway. So do I change the L5250 address to access 026D instead of 02BC???

[94Blazer383]

Ahhh...I see, well sort of. The hack I'm using doesn't have descriptions of whats at those addresses, so where do you find that info, different version of the hack??? Thats one of the issues I've noticed, depends on where the hack came from,who wrote it,is it correct,complete, etc,etc.

I would've thought that was a function, not a constant.What differentiates the two? Anyway, I'd like to put the AFR into where the Des Gov TPS is since we dont use that anyway. So do I change the L5250 address to access 026D instead of 02BC???

I think this something that Haulin figured out a while ago. I am not sure if you could do it anywhere else or not, I have never tied it.

[MSlewis]

I beleive I have this thing down, and will be testing on the way home tonight.I even took notes this time for reference.I'll post later to confirm wether or not I'm a knucklehead or have a small grasp of what I'm doing.

Later that evening..........yes my inserting the AFR info into byte 50 in the ads file has the commanded showing up in the datastream(thanks haulin), but it doesn't appear I have all the criteria met to enable lean cruise. I can see the EGR being commanded on 100% shortly after TP is pressed, and commanded is 16:1, but it's still running around 14:7 . Also no BLM update wether at idle or cruising. It's stuck at 126, o2 swinging it's ass off and everything. Interesting.
Here's what I've done; 1) 400D bit 0 checked, bit 2 checked, bit 5 checked 2) 48C7 set to max 150 deg 3) spark table @ 4859 zeroed(no valve)

[Blue71]

I don't know if this has any thing to do with it or not,
what is in the table at 4783 bit 8 ?

[94Blazer383]

I beleive I have this thing down, and will be testing on the way home tonight.I even took notes this time for reference.I'll post later to confirm wether or not I'm a knucklehead or have a small grasp of what I'm doing.

Later that evening..........yes my inserting the AFR info into byte 50 in the ads file has the commanded showing up in the datastream(thanks haulin), but it doesn't appear I have all the criteria met to enable lean cruise. I can see the EGR being commanded on 100% shortly after TP is pressed, and commanded is 16:1, but it's still running around 14:7 . Also no BLM update wether at idle or cruising. It's stuck at 126, o2 swinging it's ass off and everything. Interesting.
Here's what I've done; 1) 400D bit 0 checked, bit 2 checked, bit 5 checked 2) 48C7 set to max 150 deg 3) spark table @ 4859 zeroed(no valve)


That sounds exactlly like what mine does.

[MSlewis]

I don't know if this has any thing to do with it or not,
what is in the table at 4783 bit 8 ?

I think you might be misunderstanding the description. 4783 is the fuel reduction percentage table. Each individual cell in the table is 8 bits in length. The table itself is used for controling the reduction as it is applied to EGR operation only. Seperate from Lean Cruise but tied together for initialization of the reduced fueling strategy. I'm starting to wonder about the need to see the rise in MAP giving the go-ahead to use the open loop fuel table.

How exactly do you have yours set up????

[94Blazer383]

I looked up mine, which it doesnt really matter since I am not running an EGR valve anyway, but it set to the factory BJLF setting. I also looked at my Edelbrock bin, they raised the settings up across the board.

http://i105.photobucket.com/albums/m232/tapyz250/egrfac.gif

http://i105.photobucket.com/albums/m232/tapyz250/egredl.gif

[Blue71]

I pulled the bin back off the PCM.
I still have a problem with WB showing a higher AF then whats in the tables,
just haven't had time to work it out.
http://i266.photobucket.com/albums/ii254/93BlueZ71/EGRsettings.jpg

94Blazer383,
looks a little different then mine.
http://i266.photobucket.com/albums/ii254/93BlueZ71/ERGonvsRPMvsVAC.jpg

[MSlewis]

Here's how mine is. If you can see it.