Engine/Transmission (1998.5 - 2002) MPG problem

[aptacek]

I have a '01 QC 3/4 ton 4x4 long bed pickup. I typically get about 15 mpg.

My buddy has the same truck, gets around 18 mpg. He drives more aggressively then I do. The truck has 94000 miles on it. I recently replaced the injection pump, added a BDL lift pump (the truck has been modified with

in tank pump). I have the edge box w/ attitude on the truck. I have changed tires, (the tires before were a mud lug type tire). I checked the temp on all 4 rotors for the brakes with an IR temp gun, they were with in 5 degrees of each other. I have inspected the grease and fluid levels, on the transmission, transfer case and both axels, all were clean and to the proper level.

The truck runs @ 1500 RPMs at 55 mph on flat road. It has an automatic transmission probably has not been rebuilt. I have also checked the odometer

against the 5 miles test on the Interstate, several times, it is less the

1% off. I have used the same fuel station and same pump several times, and let trip once, top off 1 time. Soooooooooo If someone has any other

suggestions to look at, I am open to any ideas'

Thanks in advance



Andy

 

[BDahm]

any codes present? Filters ok? try using fuel from another source and/or stanadyne additive

 

[tmacod]

Same tire size and/or size calibration if possible with chip or programmer between the two trucks?

 

[grimesja]

I have a similiar truck, if you find the answer for the MPG let me know. I have gotten an average of 14-15. About the only thing I haven't done is change the turbo. I have used experimented this way:

exhaust - 3 " stright pipe, 4" MBRP with muffler, replaced MBRP with Aeroturbine muffler, now going to 5" stacks, no change in mpgs but good power increase.

injectors- RV-275, now going to Edge Mach 3 noxxles, no change in mpg, good power.

intake - changed to cool hose and tag, no change in mpg, changed to S&B cool air intake, and intake air horn again no incrase in mpg, but good power gain.

tires - went back to 285-70R-17 from 12. 5 X 35-17, no change in mpg.

replaced intercooler boots, no changes.

transmission - OEM went out at 236,000 replaced with Jasper, no changes in MPG, significant torque change

fuel - diesel, bio-diesel, and WVO, I used different fuel additives including Standyne and Amsoil no changes in MPG, truck actually runes better on bio or WVO then diesel

Edge Juice with Attitude- Edge techs say MPGs shpould be better on level three, I have not seen changes.

No codes on system with either a OBD II or from the key.



If you find the answer let m know, I'd love to get 18-20

 

[grimesja]

BTW, I have also replaced the apps, fuel pump, VP-44, and the intake air tempature sensor. No Joy

 

[DIESELWRKS]

my 2 cents

19-20 on freeway at 65 miles per hour on a gps im at 1750ish rpm. must be the stick. Ive seen some built auto's get higher but usually 2wd. I know that getting a edm cut injector would be the best for mpg IMO. does your transmission hunt up and down alot between 3-4. when is the last time it had the bands adjusted. air filter clean. your air intake temp sensor clean it. also can do the apps reset some have said this has helped with mpg but also more responsive throttle. put some higher cetane adder in a tank try this. not all trucks are even. even with all the extra add on's I cannot say anything on the edge products but my smarty and fuel saver and timing adjusting helps me alot. this last weekend I drove a total of 735 miles on manly freeway and coast line and about 20 miles of sand dunes. I used around 37 gallons for this trip. just under 20mpg.



2002 HO 6-SPD LB 4X4 QC HTT 62/14 SB-FE TST PM3/*REVO-BETA*SMARTY MACH 4'S, RINGED AND STUDS, AFE/2 " FTE 6" STACK D/PRICOL GAUGES, FASS 150, VULCAN 1/2 DRAW-STRAW, 3/8 FUEL LINE, DSS-TRAC-BAR STEER-BOX, AIR BAGS,17'' KMC BLACK HOSS, 315/70/17 MICKTHOM MTZ'S 6" RCD LONG ARM LIFT. :-laf... THANKS RIP Source Automotive Performance Diesel - Offline

 

[PatrickHansen]

When I run empty, I get 22-24 mpg @55-60 mph. No box or programmer. Michelin LTX M+S @ 65psi.

 

[dram99]

mpg could be better

driving 65 mph unmodified except for magaflow 4" exhaust, at, michelen 265X75X16, empty. . 4x4, 208000 miles,... 20-21 mpg

 

[Curious Dave]

I am on my second trans and 2nd engine. I have never seen better than 16. I have seen fluctuations with my mods, and with the crappy fuel being put out today. But I am still able to manage 14. 5 on average. That is loaded with @ 1300lbs most of the time. So I figure that if I had the old fuel, took out the weight and put 16's back on I would probably be up @ 18 or so. Not enough time to try and prove it though.

 

[MikeWinter]

Gear ratio? It comes down to 3:55 or 3:73 w/ auto trans. When I purchased my 01 several years back, I noted the axle ratio before getting behind the wheel for a test drive on several trucks. It's located on the sticker on bottom side of hood or in the glove box. I'd be curious to see what the break down is with auto 4x4 3:55 ratio owners. Compared to the same setup with 3:73 axles.

 

[georgej]

The 2nd gen diesels either had 3. 55 or 4. 10 rear axle ratios, but I believe that driving habits are more important than the ratios. I regularly get 14-15 mpg town and country road 50/50. Straight highway at 55-60 gets me 19-21. If I ramp the speed to 65-70 the mileage drops to 17-18. Every year I tow my 12300lb 5er to the east coast to visit our grandkids and will rack up about 10000 miles and the consistant fuel mileage is 11-12 mpg (averaged 11. 4).

A few thing like running 60-70 psi in the tires or using rib type highway tread helps as do things like timing the signal lights in urban traffic and not following too close to the vehicle in front. I also never let the engine idle any longer than bringing the oil pressure up when cold in the morning and clicking the seatbelt on. I usually drive about 45mph for the first 2-3 miles.

Hope this helps a little to coax a few extra miles from your hard earned bucks.

 

[rjrkihap]

Georgej, I think you hit it on the head. I'm getting the exact mileages you're getting. I've tried everything (Tire Pressure, Weight in the Bed, Canopy, Speed, Timing Only Box) and the only thing to greatly effect my mileage is reducing speed, avoiding stop and go, and keeping the weight down. I have never seen mileage above 20MPG even driving down I-5 at 55MPH. I wish there was a magic device so I could see the mileage others are getting, but no such luck.

Ron

 

[Steev]

22 tank average on the highway either at 60 - 66mph, no higher. Smarty lvl 1, bank CAI, no muffler. lost some mileage with the 285 cooper tires. I'm real easy on it, try to let the cruise do most the work on the level grounds.

When the Wifey drives it, I get 18mpg with the turbo singing away

Cold Air, Smarty and Driving technique netted me the most improvement in mileage. However, driving it like this cruds up the injectors, you gotta either run some stuff through the tank or hook a heavy trailer up for a tank to blow it out. I use a scangauge (tuned to GPS) to calculate my tank averages. You have to tell it how many gallons you filled up on each time you fill up so I believe its numbers, it's never more than . 2 to . 5 gallons off when it predicts how much I filled up with.

best I ever got was stock, freeway, 55mph cruise control, flat ground - 24 mpg tank average. Filled up right before I got on the freeway and filled up again right after. Hand calculated - I don't have an overhead lying gauge.