LBZ: Injectors and mileage

[Rogerb171]

Hey I am in the process of getting a LBZ built up...
Stock with a bully dog programmer I was getting 18mpg. Then I put an 8inch lift and 36 inch tires that are 15.50 inches wide on it.. dropped it to 14mpg.

Then I put head studs in and Industrial Injection 15% over injectors in with a level one EFI Live tune in...

I am getting 9 MPG its a pig...

Can the choice of injectors be that big of a deal? I mean brand preferences and quality of injector?

Is it time to finally install the SDP S475 LBZ Twin Turbo Kit and if I do will this increase my mileage? or is there something I am missing here? The tranny will be built but currently I just wanna get the miles per gallon back to normal..

Afe cold air intake, Ported fuel rail fitting, ppe plug, arp head studs, fass fueler titanium 150gpm, mbrp gm8424 turbo down pipe, industrial injection 50hp 15% over injector, EFI Tunes:Level 1, Tire Size:36x15.50, DSP5 Switch

 

[Rogerb171]

it has 5 inch straight pipe exhaust as well..

 

[Bustedknuckles]

The tuning and injectors should have helped the mileage. Whose tunes and have you checked it for boost leaks?

 

[Rogerb171]

Rob Coddens ATP Trucks, I sent him a log file he says everything looks good.. yeah it shoulda at least kept me at 14 mpg... I have not checked for boost leaks I guess where do I check that at obviously its part of the turbo components I suppose just find anything loose?

 

[Bustedknuckles]

Rob Coddens ATP Trucks, I sent him a log file he says everything looks good.. yeah it shoulda at least kept me at 14 mpg... I have not checked for boost leaks I guess where do I check that at obviously its part of the turbo components I suppose just find anything loose?

Make one of these and pressurize your intercooler system to about 20 lbs and see if its leaking anywhere. Stick it in the boot on the hot side intercooler pipe.

 

[Rogerb171]

cool, I will try checking for leaks and report back, Thanks for the advice!

 

[MAXX IT OUT]

Have you tried any other power levels? Generally a higher HP tune will net you better MPG IF you can keep your foot out of it. X2 on checking for boost leaks and you may want to check your injector balance rate....
Also where do you live? Right know with winter and winter fuel, I am only get 9 MPG.

 

[Low366Dmax]

36s are what's killing you. Is this hand calculated or what the lieometer is telling you?


Sent from my iPhone

 

[Rogerb171]

As far as power levels, In Level 1 optimized stock it is burning the same as level 4 Performance and level 5 for extreme performance does not help either.. they all seem to burn the same amount of fuel... Low366Dmax do you mean the speedometer is it set to the tire size or what they actually measure? The speedometer is on after the tune.. but yeah they might measure to be 35 inches high?

 

[Rogerb171]

Also yes it is switching tunes, The voltages from the efi live change on all 5 settings - and the power levels you can tell a difference on each setting

 

[JoshH]

Low366Dmax do you mean the speedometer is it set to the tire size or what they actually measure? The speedometer is on after the tune.. but yeah they might measure to be 35 inches high?

He is asking if you are hand calculating your mileage or if you are going off the number displayed in the DIC.

 

[Chevy1925]

36s are what's killing you.


Sent from my iPhone

Not enough to make the proclaimed 9mpg. I don't even get that in the city w/ 37s and 45overs. 14 is average for me

 

[Low366Dmax]

^ what josh said because there is a huge difference


Sent from my iPhone

 

[Rogerb171]

He is asking if you are hand calculating your mileage or if you are going off the number displayed in the DIC.

OH, my truck doesn't have a mpg reader.. I am just taking for instance I took a roadtrip and calculated that I filled the tank completely full to the brim. Then I drove 218 miles according to my odometer and then what I filled was approximately 22.5 gallons or so... I was driving 65mph to 70 the whole time and just taking it real easy... I am going to do another trip tomorrow and check it again..

I have a 14 mile drive to work where I drive approximately 2 miles for 30mph then I stop and drive 55mph about 5 miles stop, then 55 mph till the end and if I do this only each day with 20 total minutes of idle time warming up.. 2 days and a quarter tank is gone... I say that's about 5-6 gallons a day its real bad theres gotta be something I am missing..

 

[Rogerb171]

With no EFI live, I was getting Monday to Thursday morning 20 gallons so only 7 trips to work at 98 miles and 20 gallons of use.. absolutely ridiculous numbers! The only changes that have been made was I put head studs in, the new 15% over II injectors.. the PPE ported fitting, and the ppe plug on the fuel rail for low fuel pressure codes and a turbo down pipe.... and then EFI Live.. Changes that I would not think would make a big deal.. regarding mileage..

 

[Rogerb171]

yeah drove today 70-75 for 143 miles mostly 75 on cruise, burnt about 11.5 gallons 12.25 mpg...and this was in number 4 for mileage on efi live mode.

 

[Hot COCOAL]

yeah drove today 70-75 for 143 miles mostly 75 on cruise, burnt about 11.5 gallons 12.25 mpg...and this was in number 4 for mileage on efi live mode.

For the speed you were going, and the tune you were running, that's not terrible...you might get better economy in the #3 tow tune....you are lifted but is it leveled out and lifted?? How's your wheel alignment?

Wheel alignment will play a pretty big in role with economy with a tire that wide...

Do you have fresh fluids in all the cases and trans?

Every little thing helps...

Gears are your best bet for 36's, I'd go with a minimum of 4.11's possibly 4.56's

 

[MAXX IT OUT]

Also something you might want to check is your tire pressure, it can make a huge differents.

 

[Rogerb171]

Yes it is levelled out, I keep the wheels aligned just got aligned I will check the tire pressures!

For the speed you were going, and the tune you were running, that's not terrible...you might get better economy in the #3 tow tune....you are lifted but is it leveled out and lifted?? How's your wheel alignment?

Wheel alignment will play a pretty big in role with economy with a tire that wide...

Do you have fresh fluids in all the cases and trans?

Every little thing helps...

Gears are your best bet for 36's, I'd go with a minimum of 4.11's possibly 4.56's