Do bigger injectors effect DIC?

Porno Joe

Member
Oct 11, 2010
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South of Pittsburgh
Would my 40% injectors effect the info on my DIC, such as gallons used?

My last tank- 270 miles, I reset my gallons used and watched it. According to how many gallons I used, the truck got 20 mpg. But according to filling up at the pump, I only got 15 mpg. Seems like a big difference to me
 

Hot COCOAL

May the farce be with you
Jun 9, 2012
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you guys have the appropriate tuning for the larger injector? are your tires the same size as your computer thiks that they are?

alot of guys claim they can get slightly better economy if they try, this is the first question i have seen regarding how sticks affect the DIC? but i imagine as long as you have a good/complete tune the DIC should calculate by the ammount the injectors are spraying, not what they used to spray per injection pulse???
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
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Boise, ID, USA
Yes, big injectors will throw off the dash mileage display. On LB7s you could correct it in the tune, but on the newer trucks, it will just be wrong.

However, just having large injectors shouldn't necessarily hurt your mileage. I went from stock to 60% over, and my mileage did not change at all, or maybe went up a hair on average. It is all in the tuning. If you don't have tuning for the larger injectors, it won't run as well as it could (including mileage).
 

paint94979

Beer Nazi
Sep 18, 2006
11,715
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Don't trust your DIC for accurate mpg... Hand calculate. Yes 60% over and bigger injectors in my experience tend to get poorer fuel economy.
 

Porno Joe

Member
Oct 11, 2010
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South of Pittsburgh
Mine are 40 overs.

Tuning is correct and adjusted for tire size.

My gallons used said I only used 12 but my truck 18 to fill up at the pump.
Truck only got 15 mpg outta the last tank. Which was 250 miles of highway. Seems too low to me?
 

Hot COCOAL

May the farce be with you
Jun 9, 2012
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well how many cars and trucks did you pull on during that tank of fuel:D
it may be an issue in your right foot, or left brain, however you want to look at it:)
 

Hot COCOAL

May the farce be with you
Jun 9, 2012
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whos injectors did you use??? and who tuned it, was it a custom dyno tune, or a canned tune?
 

Porno Joe

Member
Oct 11, 2010
513
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South of Pittsburgh
Injectors were brand new exergy tips I swapped on my stock injectors. Caleb tuned the truck in the drivers seat so I know it's right. I do have a spare set of injectors I may send out to have tested and then swap those in

And I made sure to set cruise between 65-70 the whole trip. No hot rodding.
 

blk smoke lb7

<-----Lots of green $
Nov 8, 2010
5,694
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belvidere,ill
Might as well ignore the dic as far as mpg.When i had my edge and after a trip to Michigan it said i was getting 38 mpg but hand calc said 18.Dont know what is says anymore as i dont pay any attention to it anymore.
 

S Phinney

Active member
Aug 15, 2008
4,008
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Quncy, Fl
All the DIC pulls numbers from tables not actual measurements. The closet that I have ever seen is the DIC being 105 mpg better than you actually got.
 

05_LLY

Out-A-Time
Aug 7, 2006
1,756
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Norvelt, PA
Injectors were brand new exergy tips I swapped on my stock injectors. Caleb tuned the truck in the drivers seat so I know it's right. I do have a spare set of injectors I may send out to have tested and then swap those in

And I made sure to set cruise between 65-70 the whole trip. No hot rodding.

I would look at the injectors, they are rather high miles for just adding tips, balance rates dont always tell the whole story like a test bench will!
 

DuramaxPowered

Pushing my luck....
Jan 27, 2008
791
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Monroe, MI
I use tuning from Tony at Ridge Runner. The DIC and hand calculated mileage are ALWAYS with .3 MPG. I hand check it EVERY single time that I fill up.:thumb:
 

sweetdiesel

That's better
Aug 6, 2006
10,390
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Thailand
Yes, big injectors will throw off the dash mileage display. On LB7s you could correct it in the tune, but on the newer trucks, it will just be wrong.

However, just having large injectors shouldn't necessarily hurt your mileage. I went from stock to 60% over, and my mileage did not change at all, or maybe went up a hair on average. It is all in the tuning. If you don't have tuning for the larger injectors, it won't run as well as it could (including mileage).

How do you do that Dave?

you can fix it on 04-05 LLY's in the tune as well. B0781.

That would take a ton of time! And if you had any type of large PW tune it will not work:(
 

Harbin_22

Active member
Dec 4, 2010
3,858
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Southern Indiana
Not that I care at all, but with Rob's tuning my DIC is within .5 or less. With Kory's it is 2+ mpg on the low side. So Kory's tuning it will say 17mpg in the DIC, but hand calculated will be 19.2. Guess it is pulse at cruise speed or something to that nature.
 

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
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Wyoming
That would take a ton of time! And if you had any type of large PW tune it will not work:(

ive never messed around with it because I never cared enough to put time/effort into adjusting it.

I was simply stating that yes, it can be adjusted on 04-05 LLY's. (dave originally said you can only adjust it on LB7's, I was just correcting him in saying that you can adjust it on LB7 AND LLY)
 

sweetdiesel

That's better
Aug 6, 2006
10,390
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Thailand
ive never messed around with it because I never cared enough to put time/effort into adjusting it.

I was simply stating that yes, it can be adjusted on 04-05 LLY's. (dave originally said you can only adjust it on LB7's, I was just correcting him in saying that you can adjust it on LB7 AND LLY)

I understand Ben, However it does not allow enough adjustment for any BIG fuel tuned:( Pretty much anything over 2600PW it wont work.


Citis Calculator is posted on the site under timing calc.:)