OK,<br>I finally went through my first tankfull. My milage went from 10 mpg to almost 16 mpg!! <br><br>I'm not sure which fix did the trick...but i would guess the timing to 15.5* didn't hurt.<br><br>Thanks for all the help from this forum.<br><br>TJ

 

TJ - <br>Where do you do most of your driving (highway/city). My mileage after changes stayed about same for short city trips - 14 mpg but was 19 mpg for a long highway trip.<br><br>Paul

 

The milage I just reported was based on a Freeway trip at speeds or either 58 or 65 based on my speedometer. I'm not sure as to my real speed, or MPG really...but the almost 16 mpg was based on my trip odometer and filling the tank before and after. I haven't carried the camper yet to see that milage. <br>Are you saying that you get 19 mpg? <br>Am I figuring my milage correctly or should it be different? My tires are bigger than stock too. (LT235 85 R16)<br><br>Let me know.<br><br>TJ

 

I went from from 16-17mpg (15 if I played HARD) to a solid 18.5mpg when I had my timing done.

 

TJ -

If you're not running stock tires then your trip odometer/mileage will be off and will affect your mpg calculations (not to mention run you into trouble with the troopers if it's way off speed). Check your odometer against the mileage markers on the highways and see. A little math (too complicated for this simple brain) and you may be higher or lower for your mpg. Good luck.

Paul

 

You Know....now that you mention it....I found that in a mile I'm off 1/10th. That is, my odom reads .9 where it should read 1.0<br>Then I'm off 10%. So, if my mileage is 15.8 Then adding 10% would mean 15.8 + 1.58 = 17.4 mpg.<br><br>That also means that when my speedometer says I'm going 70, I'm really going 63. Dang, thats scarey! <br><br>Is the math that simple?<br><br>TJ

 

Another good way to check the odomoter and the speedometer is with a GPS.<br>I did a 500 mile trip, and found the speedometer to be right on, but the odometer<br>was off 5%, on the low side. I get anywhere from 17.5 to 18.5 with my setup.

 

TJ-<br><br>Math can be fun when it's in your favor. Better than your speedo showing 63 and you actually going 70.<br><br>You're more like 11% off (gets better all the time doesn't it). But that's splitting hairs. Somewhere I remember reading that with 4.10's at 2000 rpm it's 61 mph (stock drive train/tires). Somewhere you should be able to find the calculations for changing the speedometer gears to be more accurate. <br><br>On the down side, your truck really has more than 161K (sorry).

 

Bubba,<br><br>uumm, I think I screwed up...The numbers are not in my favor on the freeway. I should have said that I would be doing more like 77 if my speedo says 70. I got it backwards. :-[<br><br>By the way, I really needed to be told about my truck's mile being worse... thanks alot.....<br><br>Who Cares!! <br>It's still a CTD and I'm luvi'n it!! ;D<br><br>TJ

 

I put 235 85 R16's on ahd they put my odometer/speedometer right on. They changed the mpg down from the smaller stock tires.

 

im new here ansd i was wondering were i could get the tools to check my timing i have a 1st gen with the bosh pump

 

If you have .250&quot; dia lines, you can get an adapter and use a timing light. Snap-On is one source, but I found this one more reasonable.