Mileage Increase on Trucks

[MSURacing]

What have you guys been seeing for a fuel mileage increase on the full size trucks and SUV's? I have an 01 Yukon XL, 3" lift, 325/60R18's, 3.73's and I am seeing right around 16 now. I haven't done a comparision to the stock cal in a long time, but I thought it was around 14 to start.

Also, i put it on the dyno here at work and got 252 hp and 279lb ft. Not to bad for an intake and cat back.

[cmitchell17]

With my 2000 5.3 ext cab Since Ive lowerd O2 switch points and added some timing based off the optimal timing table I can get about 21-23mpg crusing at 45-60 and about 17-20 avarage city/hyw.

So far Ive probably got on avarage about 2-3mpg more especially on cruises.

[n6oli]

I have a 1999 5.3 ext. cab, and I lowered my O2 switch points to:

CL Mode Bank-1 Bank-2
0 460.015667 460.015667
8 460.015667 460.015667
16 460.015667 460.015667
24 460.015667 460.015667
32 460.015667 460.015667
40 465.000356 465.000356
48 469.985046 469.985046
56 475.003646 475.003646
64 479.988336 479.988336

What did you set yours at cmitchell17?

[dc_justin]

I have a 1999 5.3 ext. cab, and I lowered my O2 switch points to:

CL Mode Bank-1 Bank-2
0 460.015667 460.015667
8 460.015667 460.015667
16 460.015667 460.015667
24 460.015667 460.015667
32 460.015667 460.015667
40 465.000356 465.000356
48 469.985046 469.985046
56 475.003646 475.003646
64 479.988336 479.988336

What did you set yours at cmitchell17?

Drop the CL Mode 0,8,16 to something quite a bit lower... 250-300mv and you should see a slight improvement. Your table is still richer than 14.7:1 across the board (450mv).

[n6oli]

Could you copy with labels from your tune, and then paste in a message what you have yours set at?
Sorry, I didn't see who sent the message. I thought you were cmitchell17?

[n6oli]

Why does GM have the O2 switch points set so high in their tunes?
This is the factory switch points.

LABELS bank
CL Mode Bank-1 Bank-2
0 480.022245 480.022245
8 480.022245 480.022245
16 480.022245 480.022245
24 480.022245 480.022245
32 480.022245 480.022245
40 480.022245 480.022245
48 489.991625 489.991625
56 509.998203 509.998203
64 520.001492 520.001492

[cmitchell17]

Hey mine are:

372.495363 372.495363
372.495363 372.495363
372.495363 372.495363
373.343100 373.343100
375.208120 375.208120
380.565813 380.565813
450.012377 450.012377
450.012377 450.012377
450.012377 450.012377

Let me read up on Dc Justins post to see what he said to do.

[cmitchell17]

CL Mode Bank-1 Bank-2
0 372.495363 372.495363
8 372.495363 372.495363
16 372.495363 372.495363
24 373.343100 373.343100
32 375.208120 375.208120
40 380.565813 380.565813
48 450.012377 450.012377
56 450.012377 450.012377
64 450.012377 450.012377

[cmitchell17]

I can't figure out how the closed loop modes range? Do the low ones like 0,8 just the light loads and then the 16-24 seem like they control about the same load levels?

How should the switch points ramp up to 14.7? Should it be 250-300mv for just like 0,8,16 then quickly go up to 14.7 from there. Becuase you want it close to 14.7 going up a hill in a low gear right?

[cmitchell17]

This is what I have now


LABELS bank
CL Mode Bank-1 Bank-2
0 261.245820 261.245820
8 270.802185 270.802185
16 288.003642 288.003642
24 337.696740 337.696740
32 406.502567 406.502567
40 450.461846 450.461846
48 450.012377 450.012377
56 450.012377 450.012377
64 450.012377 450.012377

[dc_justin]

I can't figure out how the closed loop modes range? Do the low ones like 0,8 just the light loads and then the 16-24 seem like they control about the same load levels?

How should the switch points ramp up to 14.7? Should it be 250-300mv for just like 0,8,16 then quickly go up to 14.7 from there. Becuase you want it close to 14.7 going up a hill in a low gear right?

That's something that you'll need to figure out. The closed loop mode airflow is defined in the PCM. What you'll need to do is figure out what your airflow is at cruise, look up the corresponding closed loop mode and go from there.

[n6oli]

I've been looking at some tunes on holdencrazy.com, and they started putting the O2 switch points at 450mv across the board starting in 2003 for the LM7 engine.
That seems like the best route to go.
The way I came up with my O2 switch points is to go out and log some data, and then highlight the HOSS11 V and HO2S21 V in the cruise and idle sections to get an average. (This is after the AutoVE/MAF tune to make sure my commanded AFR equals my LC-1 wideband AFR)
Don't know if this is the best way, but seems like the logical way.
I'll be doing some more research on this to find the correct way.
I love this stuff. It gets very addicting!!

[dc_justin]

The 450mv switch point is where the O2 sensor is most precise and represent stoich. If you want to achieve slightly less fuel consumption, then you can lower the switch points in low load regions.

[Lextech]

Would lowering the O2 switch point be something that should be done if running a Custom Operating System. Specifically, You can command your A/F ratio in B3647, so would you want to drop the Switch Points.

[dc_justin]

Would lowering the O2 switch point be something that should be done if running a Custom Operating System. Specifically, You can command your A/F ratio in B3647, so would you want to drop the Switch Points.
The only benefit to doing so in a custom OS would be to retain closed loop operation in those particular cells. Otherwise, you'll have no need to adjust the switch points.

[deadsquirrel]

hey guys i am trying to tune a friends 2007 5.3 and i read about you closed loop stuff and cannot figure out how to relate it to the 07's....and suggestions on simple things to do in the new operating systems to gain some power and milage???

[TAQuickness]

Welcome to the forum deadsquirrel!

[deadsquirrel]

Welcome to the forum deadsquirrel!
thanks just tryin to learn the ins and outs of the gasser world of tuning:muahaha:

[horsehaulin]

With my 2000 5.3 ext cab Since Ive lowerd O2 switch points and added some timing based off the optimal timing table I can get about 21-23mpg crusing at 45-60 and about 17-20 avarage city/hyw.

So far Ive probably got on avarage about 2-3mpg more especially on cruises.

When you say you added timing, what do you mean, could you help me out a little. I am tuning my step dads truck for better economy.

Tony

[cmitchell17]

So far I havent noticed anything from adding timing in part throttle non pe.

You can experiment with it but I don't think it will help.

I think the factory timing would be the best timing, except the timing in PE high throttle beucase the stock tune is always consiveritive in the high load regions.

[dc_justin]

So far I havent noticed anything from adding timing in part throttle non pe.

You can experiment with it but I don't think it will help.

I think the factory timing would be the best timing, except the timing in PE high throttle beucase the stock tune is always consiveritive in the high load regions.

You might not feel it seat of the pants, but a load bearing dyno definitely shows a worthwhile power gain at part throttle.

Justin

[horsehaulin]

Ok I feel like a moron! Could one of you help me out a little, what part of the timing table should I adjust? And how far should I adjust those sections? I understand the diesel side of the house, but gas is much differant to me.

Tony

[cmitchell17]

I would just add timing in the fuel mixture correction table. So it only adds timing in PE. I think that timing at part throttle cruise is fine the way it is stock, but the stock tune dosent have enough timing at high throttle/ pe mode.

[horsehaulin]

What is PE mode?

[ScarabEpic22]

PE= Power Enrichment mode, think of it as WOT mode where fueling is completely Open Loop via PE tables (and if negative? LTFTs fuel is added) and the NBO2s are disregarded.

[horsehaulin]

So what adjustments should I make to the PE table?

Tony

[cmitchell17]

You can start with probably about 2-3 degrees. Don't add more than that in the 3600-4800 rpm regions where peak torque is. So add a little more in the 2400-3400rpm regions becuase their is less airflow in thoes regions.

The stock tunes (especiall for trucks) always seem to drop timing as the rpms increase. For the stock cam (trucks) it looses a lot above 5400rpms so I think a lot more timing can be added above 5400 becuase airmass drops so much above that.

From what I have learned if air going into the engine is low you will need more spark advance but if you have more airmass going in their will be more compression and less timing needed becuase of the faster burn rate.

So basically a timing table should look about like an inverse of the ve table.

I hope this helps you.

[Wolfie]

I have a 2007 Chevy Express 2500 Extended Van /w 6.0L that I haul in.
I have the commanded AFR set at 15.5, added 4 degrees timing across
the board in the high octane table, made the dfco just a bit more
aggressive (couldn't do much because EFILive can not adjust the
cut off point on this vehicle), tightened the tranny, and did an auto-ve.
I went from around 13.5-14 to 17-17.5 so far. Oh yeah, the cats
somehow leaked out of the exhaust. I'm still looking for more though.

[horsehaulin]

You can start with probably about 2-3 degrees. Don't add more than that in the 3600-4800 rpm regions where peak torque is. So add a little more in the 2400-3400rpm regions becuase their is less airflow in thoes regions.

The stock tunes (especiall for trucks) always seem to drop timing as the rpms increase. For the stock cam (trucks) it looses a lot above 5400rpms so I think a lot more timing can be added above 5400 becuase airmass drops so much above that.

From what I have learned if air going into the engine is low you will need more spark advance but if you have more airmass going in their will be more compression and less timing needed becuase of the faster burn rate.

So basically a timing table should look about like an inverse of the ve table.

I hope this helps you.

What table should I do this in?

Tony

[cmitchell17]

B5908 is the fuel spark correction table. It will add/subtract timing based on what air fuel ratio the engine is running at. Meaning it will add timing when in PE mode becuase in PE mode the fuel mixture is richer.

[horsehaulin]

Thanks for all the help.

Tony

[cmitchell17]

How did it work with the timing?