Gas Mileage Issues

bdillon94 · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

jrrod2004 · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

A few things come to mind (Others will add to the list):

Throttle body clean?

Air Filter new or reasonably clean?

Fuel pressure ok?

Any sticking brakes/calipers?

Type of tires and load range?

Tune up completed?

Quality of fuel being used?

Rear end ratio?

txab · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

A few things come to mind (Others will add to the list):

Throttle body clean?

Air Filter new or reasonably clean?

Fuel pressure ok?

Any sticking brakes/calipers?

Type of tires and load range?

Tune up completed?

Quality of fuel being used?

Rear end ratio?

+1

Is this a new vehicle to you or have you been driving it and the mileage has dropped off? As Mike points out, if the ratios of the vehicles you are camparing to are different than yours, the mpg will be different. Has the speedo/odometer been recalibrated for your tire size? Have you changed gear ratio to compensate for your tire size?

Tsmith · August 26, 2009

"I am only getting between 6-8 mpg"

Kinda reminds me of my big honking jacked up '78 GMC. 10 ~ 11 mpg was tops on the HWY.

Crazy Canuck · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

A few things come to mind (Others will add to the list):

Throttle body clean?

Air Filter new or reasonably clean?

Fuel pressure ok?

Any sticking brakes/calipers?

Type of tires and load range?

Tune up completed?

Quality of fuel being used?

Rear end ratio?

+1

Is this a new vehicle to you or have you been driving it and the mileage has dropped off? As Mike points out, if the ratios of the vehicles you are camparing to are different than yours, the mpg will be different. Has the speedo/odometer been recalibrated for your tire size? Have you changed gear ratio to compensate for your tire size?

If the mileage has just dropped off, you could have a problem with your oxygen sensors as well. Usually when they start to go, the ECU will run the mixture quite rich and it will hurt your economy while it does it.

jrrod2004 · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

Another question: You mention injectors, do you have a diesel or gas engine....?

cliobogger · August 26, 2009

it has a 6.0 gas. all 1500hds only came with that engine. i have the same set up only im running 35s with 30k on it. and its an 06. 10-14mpg

Stevens03 · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

A few things come to mind (Others will add to the list):

Throttle body clean?

Air Filter new or reasonably clean?

Fuel pressure ok?

Any sticking brakes/calipers?

Type of tires and load range?

Tune up completed?

Quality of fuel being used?

Rear end ratio?

Along with that, clean your MAF sensor too. It does make a difference. Also might want to consider a full synthetic fluid swap. I know with my 03 I saw a full 1-2 mpg difference with just swapping the ATF to Royal purple max ATF fluid. Very pleased. Also what exhaust do you have, if you have flowmaster, then ditch it. I had it, and swapped to magnaflow and saw an increase as well. Flowmaster caused my truck to loose low end torque which is what you use when pulling out from a stop...

Just a couple more ideas for you.

cliobogger · August 26, 2009

im about to ditch my 2 rustmasters. idk if id have to compleetly redesign the exhaust though. are magnaflows just as skinny as flowmasters? if not ive got problems. haha.

66nova · August 26, 2009

im about to ditch my 2 rustmasters. idk if id have to completely redesign the exhaust though. are magnaflows just as skinny as flowmasters? if not ive got problems. haha.

Depends on which ones you buy, but in general yes. I bought the 16in Magnaflows for my car, and they basically welded right into place. I think you will love the sound. I personally like it better than the flowmaster and I love flowmaster sound.

For the OP, I think these guys have you right on track. Good fuel system cleaning, TB and injectors. Clean the MAF and see what you get. Those things are easy and should be done regularly anyway.

Zembonez · August 26, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

10 MPG would be understandable. Your mileage indicates something is wrong for sure if you aren't driving with your foot on the floor all the time. Are you getting any SES light or setting any codes?

grayghost7 · August 26, 2009

Wow....10-14 sounds bad to me now. My '70 C10 LWB 355/350/3.08 got 12 on the hwy.

spikesputnik · August 27, 2009

Ok, here's the deal. I have an 03 1500HD that has 177K miles, 6" lift and 33"tires. My problem is that I am only getting between 6-8 mpg. Is this normal? What if anything can I do to increase my fuel economy. I have talked to others with the similar vehicle/age/mileage/mods and they are getting 10-14 at the very least. I was first thinking restrictions, then maybe fuel injectors (fuel system). I'm not sure where to start. I live in Germany so I don't have acces to a good shop that can test my injectors. Any thoughts?

You drive that thing in Germany, where the measure petrol by the litre? And for what 1.5-2 e per? And where your truck is bigger than the auto shops anyways?