Hey guys-

New to diesels so go easy on me.

I have a 98.5 (24v) full sized beauty. leveled due to air bags in the back. 35" tires. Now to the engine work, I'm not 100% sure what all is done, turbo/blowoff is louder than other stockers I've driven, the guy before me said it's got a 50hp chip in it(no brand no paperwork, so i dunno), K/N filter, 4" straight pipe MBRP exhaust. I don't have any boost gauges or anything, but I'd like to get those too. I get aroudn 14 mpg average, up to maybe 16-17 on the highway but I don't really ever drive on that. My neighbor has an 01 w/ a 6 spd in it and gets around 20mpg.

What do I need to do to get the mpg up a little?

it's silly to comute in a truck getting 14 mpg around town. I know the tires bring it down, but they shouldn't affect it THAT much. I'm wondering if I have some bigger injectors or something. Speaking of injectors, I've heard that simply cleaning injectors can imrove gas mileage significantly, is there any validity to that?

Maybe I need to get an adjustable chip and adjust it to fuel economy? It would be nice to have the option to boost power a little, I'm shopping for a tractor right now that'll be in the 6-8000lb range, I won't tow it often though.

Thanks guys,

Tyler

 

Aftermarket injectors usually help mileage, and could be a viable option for you. Next step is to find out what chip is in the truck, and is it a fueling or timing chip?

35's will destroy mileage, heavy right foot will kill mileage, and so will speeds over 60-65. Make sure your brakes aren't dragging, all the fluids are fresh, transmission isn't slipping, etc...

Also, a bad MAP or IAT sensor could/would cause poor mileage. IAT can be cleaned with contact cleaner, and the easiest way to check the MAP is with a scanner or power chip that displays boost.

 

If you have 4:10 gears 16-17 sounds about right. If the 01 has 3:55's 20 sounds about right.

 

I drive it like a grandma so leadfoot isn't killing me, if i drive it like I want to it's down probably to 12-13mpg. the tires probably only bring it down maybe 1mpg don't you think? When i get new ones I'm going to put 33's on I think. i like the bigger tires for getting to hunting/fishing spots so I don't want to go too small. Maybe I should just get another set of stock tires for commuting in and keep the 35's for off road.

Never hit freeway speeds, usually 35-50mph. I'll check brakes this week, they don't make any noise and work great so I hadn't even thought of that. tranny is fine.

What is the IAT sensor, where do I find it?

do I need to take it to a shop to have them scan the MAP?

How much would it cost/can you switch from 4:10 to 3:55s?

 

if you have to buy a new set of gears and have someone install them, more than they are worth in fuel savings

now if you can find some one that wants 4.10's on trade for their 3.55's and can do the work yourself, then you would profit

 

Alright, I'll look aroudn for a swap. I definitely can do the work myself, unfortunately (just for this) it's a 4x4 so I gotta do both axles...

been reading up more and it looks like youre supposed to "reflash" your ECU if you put on bigger tires. will that only correct your speedo, or will that have an effect on engine efficiency or anything?

Is it worth having your injectors cleaned/ how do they clean them? Could you just take em out and soak them in brake clean or whatever?

Since youre answering questions, anybody got a dollar value for putting in some boost/ tranny temp/ fuel pressure gauges? And, is it hard to put that stuff in? i'm not an acomplished DIESEL mechanic, but I've rebuilt my motorcycle/been working on gassers since I can even remember.

thanks for all the advice

 

Oh, where to start young grasshopper...

This should cover the IAT/MAP. All a scanner will do is show you if your MAP is registering boost or not.
http://dodgeram.org/tech/dsl/sensors/IAT/clean.htm

285's from stock 245's sucked my mileage down 2mpg. I gotta imagine 35's would be worse.

You didn't answer about the chip, but whatever it is should be sold. The profits from that could/should be put towards something like a Edge Juice/Attitude or a Quadzilla Adrenaline and optionally a Pulse. This will cover all your gauges and you'll have a chip to add some power too! My sig pretty much covers what I'd recommend.

Cost to switch gears would be pretty astronomical in comparison to the fuel savings.

You could get your injectors cleaned, pop tested, and possibly rebuilt. Your other option is to pick up a small set such as RV275's. They add a little bit of power, and a little bit of mileage. Pensacola diesel has a set of injectors for just a bit over 200 bucks if memory serves and they would be pretty comparable to RV275's.

Flashing the ECU only compensates the speedometer. Which brings up a good point. How are you calculating your fuel mileage? By hand? Are you correcting for the difference in tire size?


Good luck,
Shawn

 

you should do a serch on here for mpgs there have been alot of threads about it and some really good ideas. probibly ansure about 90% of your questions and theres always someone an here happy to ansure the last 10%

 

Hey-

Thanks, I did forget to answer your chip question. I have no idea , sorry.

I was taking into accoutn the tire size when calculating the mileage, i've got it written down in the truck but it's a multiplier I found on the website somewhere. Basically: miles/gal*multiplier for 35" tires = around 14mpg

I've been reading up a lot about this stuff the last few days since it's a bit slow at work but there is so much **** information it's gonna be a while before I feel confident in making any decisions... I'm also very OCD about knowing EVERYTHIGn before i buy something, especially when its hundreds of dollars.

I'll research your chip/gauge suggestions as well as injector choices.

I'll also look into getting a set of craigslist wheels/tires that are smaller than 35's but I think if could get it chipped better maybe w/ some injectors it would be good enough.

How much mpg gain are we talking about with the things you suggested (new chip, maybe injectors?) I'm thinking it's going to be at least 700 bucks for the 2 of those things so I've got to get a decent gain.

 

for some extra power and the milage id go with a XZT+, looking for cheapest option, do like me and pick up some used gages, then the RV275s u should get atlesat 3 maybe 4 mpg with that. my sig sees 23 if i drive slow on the freeway and thats stock injectors but i have the hub kit so...

 

Some guys say that they get 23-26 MPG. If you set your truck up just like theirs, it would help your's some (2mpg's or so). don't expect mericales. Some trucks just get better than others, and no one can really tell you why. Are you sure you have 4:10's? if so your not going to beat 18-19 max with a 4X4 (down hill both ways). Smaller tires would be the best place to start. AND on a 24v truck an incab fuel presure gauge is worth it weight in alunamin (least face it gold is $900+ per oz. and the gauge weights several ounces).

 

After unhooking the IAT sensor plug is there anything else ? Mine looks like it has some type of protective cover. Is this possible. I couldn't get the 13/16 deep well to fit over it.

Mike