I just had the TC replaced in my 06 mega and it SEEMS that I may not have OD, at 75 mph indicated I'm showing about 23-2400 rpm which seems hi to me, my 01 was at about 2100 IIRC. I tried a gear ratio calculator and with my 4.10, OD auto, 285/70/17s it spit out just over 2000rpm at 70. Why i didnt run it at 75 IDK, just dumb. I'll go cruise at 70 indicated, and maybe take the GPS to confirm tomorrow. I just cant get past the lousy fuel mileage of this truck, 14-15 mpg calculated? Empty? Just doesnt seem right somehow

What kind of RPMs are yall seeing at steady state cruise?

Thanks

 

That looks about right for the RPMS at that speed. It is around 2300 for me at 75 mph. I have never ran 2000 rpm at 70mph. I am using the stock tire size.

 

It's correct. Been a long time for me, but I recall around 2000-2100 at 70 with stock tires and 3:73.

A simple test is when your TC locks up at around 50mph, turn O/D off and see if your RPM's jump up.

As far as mileage, it's about right for a MC 4X4 with 4:10's.

Stock I averaged 17+mpg combined HWY/CTY, but I was on the high end of averages.

 

Thanks, i guess ill just have to adjust to the new mileage, I seem to be in the general ballpark with everyone else, maybe on the low end but in the ball park. First tank from Colorado Springs to Wheatland Wy was about 14.5 or 14.7 but we also had 50mph crosswinds for much of it. From there to Rapid City SD I havent filled up yet but likely about the same. Id LOVE 17 ave about now.... Glad fuel is under $3 gal in some places

 

Have u taken into account, the tire size, u'r tachometer, 4.10 gears your actual reading may be different, my 04.5 came with stock 245-75-17 --3.75 gear, at 2025 rpm = 70 mph, and i upped to 265-70-7 and all readings are the, same avg. 17 -20 depending on conditions, tow between 13-15 or better depending on tow amount, size. Calculate your true readings.

 

i did, I did a 10 mil odometer check over two different stretches of interstate and was off by 0.3 and 0.4 so 3-4% under what it should be, assuming the highway mile markers are accurate. When I added in the 4% on the last part tank (~285m) between 65 and 70 and then maybe 30 mile in town and came up with 14.7 mpg. Lie o Meter said 17 even. I guess it just is what it is

thanks

 

If you want to quick way to check your speedometer, get the speedometer app for your phone. It is quick and painless.

 

thanks Spooler, I was going to grab the GPS out of the Jeep but forgot it, my phone is an antique that is just a phone, maybe when I finally move into the 2000s and get a smart phone I will

thanks