Engine/Transmission (1994 - 1998) mpg?

[Ahopper]

i have a 97 12valve with a #5 plate i belive. the star is turned out a bit. it is also strait piped. i have bigger tires and its 4x4. my ? is im getting 9-10 mpg :{ on highway pulling 8000lbs and 10-11 in town not pulling anything. is there anything i can do to get better gas milage? is this normal? i thought i should be getting more.

 

[KingS]

how big are tire my truck don't like bigger tire I lose alot of milage but other guy don't notice so that is a toss up but the star wheel does effect it at least on my set up if I turn it up like everybody tell me to I loss milage and some torque when I had just the #5 plate and no gsk my truck performed the best and got best milage with the star wheel set 70 to 85 clicks back from full forward and now mine likes it right about 45 click hope that helps alittle. I get 21. 5 highway and 15. 5 17. 5 pulling.



My dad's 97 is stock with full plate slide full foward afc slide full foward and star wheel 74 click to get best mix of performance and milage he ranges between 17. 5 to 19 highway and city driving

 

[Ahopper]

the tires are 295/75/16 the star wheel is turned maby 10 to 15 clickes forwared from stock. i dont know if it makes a diference but the wast gate is also disabled. another ? is if i turn my timing up will i get better mpg?

 

[REFLOYD]

yes if you up the timing you should get better milage but it won't be that much.

 

[Ahopper]

so are my mpg#s normal? or is there any way i could get better?

 

[REFLOYD]

well you can see what my truck is and the mods on it and i get only about 13. 5 in town empty. And on the highway empty it is about 16-17. oh and the star wheel is about half way between stock and all the way in.

 

[Ahopper]

how hard is it to get your timing done and does anyone know wher i could get it done in the phoenix area? and also if i pushed the fuel plate up would that help or not? im sorry for all the ?s i just need something to get better mileage. fuel is just to damn expensive!

 

[REFLOYD]

setting the timing is easy once you have the tools. If you slide the plate forward it will give you more power but less MPG. If you slide it back it will give you less power, remember the plate is what the governor arm follows and that controls the rack travel. IIRC the plate really only effects the engine at WOT.

 

[Matthug]

Something is wrong to be getting that kind of mileage. Timing will help 1-2 MPG. Check for fuel leaks first.

 

[Ahopper]

i checked for leaks i didnt see any thing is ther a particular place that might be more prone to leak??

 

[Ahopper]

another question if turned the star weel back will i get better mpg? also how do you know how many "clickes" turn the star weel what do you use to turn it back? someone said you turn it back from the front how far forward do you turn it? i cant seem to get it any more forwared because the hole to get to the weel isnt big enough. im sorry for all the questions i just am confused

 

[WAnderstrom]

Sorry to hear about your mileage troubles I had the same issues with my 95 auto. I did several things that all combined to improve my milage from 12 mpg empty to 18. 5 empty. I think the biggest help was getting the transmission done with a lower stall torque converter, this alone bumped me from 12 to 16. 5mpg. Advancing my timing and fixing fuel leaks I think gave me the rest. As far as what plate you have, it's position, AFC, star wheel and their position, and what GSK kit you all have are controlled by your right foot. I have all my stuff adjusted for maximum HP and I feel I get great MPG, I'll take my 18. 5 mpg combined city/hwy anyday. Just my humble opinion and personal experience. Oh, almost forgot, my timing I found when doing the KDP had slipped to 9 degrees, it is now at 16. 5.



Good luck!

Will

 

[moparguy]

Ahopper, what Will said plus, speed does indeed kill. Fuel mileage that is. If when you're pulling 8k, your're running 75ishmph with a highprofile trailer, then 9/10mpg sounds about right. If you're running 60mph, something is up.



Of course the around town mileage sounds low. With my truck, running empty, mileage can be as low as 14. 5 to as high as 20mpg (highway 55/60mph). All depending on how hard I drive.

 

[MacMc]

so are my mpg#s normal? or is there any way i could get better?

I'd sure like to know, too. I expected more (at least a little) from my 96 3500 4x4. I got 12. 5 MPG, which was at least 25% better than my 460 '95 Ford.



It took me a few weeks to adjust my driving style. I'm used to driving my big-block like a dragster. After I settled down and started treating this truck like a big rig, my mileage WENT DOWN to 11. 5 MPG. What's up with that?



But, my last few tanks have been Shell, which is that new low-sulphur stuff with the warning label against usage in 2007+ engines. Can that be that bad?



My truck is NOT heavy. It's an extended cab with the stock bed still. I've got a 600# welding machine and a big toolbox. That's it, so far.

 

[McLaughlin]

I used to get about 19 mpg around town when stock then in a period of about three weeks it dropped to 12 mpg. After several mods and stuff, the mileages is now up to 19 hwy and 16 city. Seems like I had an injector start hanging a bit open. When I was having the problem, I was told I always had a white/gray haze comming from the tail pipe. I couldn't see it but anyone following me could.



Check out the boots to your intercooler really close. They have a reputation for cracking and leaking.

 

[Ahopper]

another thing to ad is i think my egt are high. at empty on the highway i can hit 1250. (probe pre turbo). and in town just crusing im at 800-1100. i dont know if thats normal or not. also befor shutting down the truck at idle for 2-3 minutes it wont go below 450 is that normal? can high egt have anything to do with bad mpg?

 

[Matthug]

Thats definitely not normal EGT's. What kind of boost is it running?

Sounds like what someone else mentioned, some injectors are hanging open and dumping in more fuel causing high EGT's and poor fuel mileage. Does it seem to run rough at all? Rough idle?

Either way it's never a bad idea to replace injectors, their pop off pressure's start to be different from one another after about 150K miles with sometimes being earlier.

 

[Ahopper]

my max boost is around 40psi on the stock turbo. i know thw turbo can only handle around 35psi but when i screw the screw in on the boost elbow the egt go up. right now i dont know if the mods i did were even any good i have more power but seem to be having alot of problems. the truck only has 93k on it could the injectors go that early? is getting new injectors the only way to fix them from not "staying open"?

 

[Ahopper]

it does run a rough idle with the ac on. it slightly seems to pulse i guess is what you would call it

 

[Kawi600]

I was getting 10mpg with my 95. Upgraded to a DTT transmission with a tight convertor and it got me up to 13/16. The OEM is pretty junky.

Next step will be a 215 pump and injectors to get rid of any potential problems there.