MPG

[HARDTRAILZ]

Just wondered how the other lifted trucks are doing in this department. Also what you have done to try and keep yours decent since almost all our mods are a detriment to mpg.

I just went to Chicago and back and actually got a bit over 16 mpg running 80+ mph. I had 292 miles on the trip ticker and put 18.063 gallons in. I have gutted the airbox, Green Air Filter, PCMforless tune, custom exhaust from cat back and it seems to work.

[Philberto]

My WAG would be that I'm around 16 or so combined on 31.55" tires and with no other mods. PCM4Less tune has been bought, but not used due to the vehicle being a DD and me being to lazy to get the motorcycle out of the garage. Will have to look into that...

[foosh]

Our trucks really like high speeds, where they can just drop into overdrive, and the added weight from our big tires help carry us threw the small hills so we don't downshift to 4th. I Actually got 19 mpg at 80 but that was running with a decent amount of cars on the road (the draft of other cars help quite a bit) and my speedo and everything is still off so it calculates to be like 21 mpgs. Not to bad for a lifted truck on 33's, but the around town is pretty bad, 13 maybe in city driving. 15 in mixed.

[bartonmd]

Our trucks really like high speeds, where they can just drop into overdrive, and the added weight from our big tires help carry us threw the small hills so we don't downshift to 4th. I Actually got 19 mpg at 80 but that was running with a decent amount of cars on the road (the draft of other cars help quite a bit) and my speedo and everything is still off so it calculates to be like 21 mpgs. Not to bad for a lifted truck on 33's, but the around town is pretty bad, 13 maybe in city driving. 15 in mixed.

I'm sorry, but I just have to call a "WTF" on this... Our trucks' gas mileage HATES high speeds (I get 21 at 68mph, 19-20 at 73mph, and 18-18.5 at 80mph), because they are a box... Lifted trucks even more, because there is more surface area from the more exposed suspension components... (round stuff like the rear axle is about the worst shape for aero drag)... I would believe your mileage if it was one trip, there was some pump error (i.e. you're calculating it, not getting it from the DIC), and/or you were on your way home from the mountains (i.e. going down hill)... I get like a 2mpg difference between going from the flat lands up into the mountains, and from the mountains down into the flat lands...

The M/T tires have pretty high rolling resistance (and more air turbulence around the side lugs) compared to AT or HT tires, at the same pressure... This counteracts the momentum from the heavier tires pretty well...

4th is OD

Mike

[Trail X]

Hehe... well said Mike.

I was in the habit of driving at 75 or so, but began getting horrible highway mileage... like 14mpg... 13 with a tire on the roof. So I did a few things to counteract it...

Moving the tire off the roof was a must for me. That easily gained back 2 mpg. Then by reducing my cruising speeds to 70 I gained another 2 mpg. So before the front bumper was added, I was at about 17 mpg highway.

With the new front bumper, it's brought me down to about 16 (that's without the roof rack, which is only installed for trips).

On the trails, I get about 6mpg... hehe.

And I will agree, if you have a lot of traffic at a steady high speed, the draft really can be a big factor. Still... 21?

[MrSmithsTB]

In his defense. Not carrying a tire on the roof and running A/Ts.

[irishboy02]

In his defense. Not carrying a tire on the roof and running A/Ts.

And he has 3.42s

[foosh]

Plus i was drafting the entire time, never downshifted... Its only been that good a few times. I'm just saying every once in a while i do get decent mileage. Normal is 16 at 80, and I absolutely get better mpgs at high speeds I've tested it. Last year i made it over 350miles from tecore to back home used 20 gallons and averaged 85 = 17-18 mpg. (85 was only bc my friend who came with me's mom and sister just got hit and rolled their suburban and his dad was away so we had to get back asap). Sorry not trying to make an mpg war here, just saying that I get decent highway mileage (my city is pretty bad).

[dirtychevymama]

OK the numbers:

Last week, less warming up time I averaged 14.5 MPG.
Today, more warm up time & with pulling the trailer a bit I averaged 12.5 mpg.

Mostly in town or the dreaded Mall cruising mode.

Throttle body cleaned a few weeks ago. New fuel filter, Royal Purple, Transmission filter & fluid this month.

[Zero]

i have been getting shitty millage ever since i got the lift and the big tires. but then i got the pcm for less tune and i thought it would help some. especialy after correcting the spedo. but come to find out, my spedo is still wrong. good thing i spent the extra cash to buy another computer. so back in the stock one goes, and back to pcm for less for a re tune.

alvin said he could fix the speedo issue no problem. so i will keep my final verdict to my self untill i get these issues solved. and can make a fair assesment of my situation.

[Trail X]

Same thing happened to me. After the second tune, they didn't get the speedo fixed. Plus my transmission began shifting extremely hard (no, I mean EXTREMELY hard).

I returned it for a refund and got a scan gauge for the speedo adjustment. Much better use of money if you ask me.

[Zero]

Same thing happened to me. After the second tune, they didn't get the speedo fixed. Plus my transmission began shifting extremely hard (no, I mean EXTREMELY hard).

I returned it for a refund and got a scan gauge for the speedo adjustment. Much better use of money if you ask me.

so to be clear, alvin never got ur speedo to read the correct speed? my tranny has a pretty hard shift but i figured that was because of the shift kit and vette servo i put in.

please correct me if i am wrong but my theory is if i can get the speedo corrected properly, i will get better millage.

do u miss the power improvement from the tune?

[teebes]

Same thing happened to me. After the second tune, they didn't get the speedo fixed. Plus my transmission began shifting extremely hard (no, I mean EXTREMELY hard).

I returned it for a refund and got a scan gauge for the speedo adjustment. Much better use of money if you ask me.

I had similar issues on my second tune. Speedo wasn't fixed and my trans didn't know what gear to select at highway speed. Would down shitf, up shift over and over. Yikes.

[Zero]

Same thing happened to me. After the second tune, they didn't get the speedo fixed. Plus my transmission began shifting extremely hard (no, I mean EXTREMELY hard).

I returned it for a refund and got a scan gauge for the speedo adjustment. Much better use of money if you ask me.

I had similar issues on my second tune. Speedo wasn't fixed and my trans didn't know what gear to select at highway speed. Would down shitf, up shift over and over. Yikes.

wow, i didnt realize you guys had these problems with pcmforless. i think i need to have a nice long chat with Alvin, or worst case i get my money back, keep the extra computer, and buy hptunners to tune it my self with my boss.

[Philberto]

wow, i didnt realize you guys had these problems with pcmforless. i think i need to have a nice long chat with Alvin, or worst case i get my money back, keep the extra computer, and buy hptunners to tune it my self with my boss.

I'm also interested in the outcome of this, as I purchased a tune for their Labor Day sale, and have yet to send my computer in.

[Trail X]

This was in an email to Kelley once I decided to return my pcm:

I've had 3 issues.

First, the 1>2 shift. This seems to be due to an overheating issue in the transmission. As soon as you get off the interstate and require a 1>2 shift, the transmission will pound into 2nd gear, shuddering the vehicle. I know this is not intended and is not good for the transmission. It will continue this poor shifting until the vehicle has been shut off for 10-15 minutes and the transmission cools down. After driving for another 10 minutes, the transmission will begin to slam again.

Second is the issues with the torque converter clutch. The PCM is throwing codes P0894 (Trans component slipping) and P0741 (TC clutch stuck off). These codes have appeared while at highway speeds, and the vehicle is coasting. They both appear to have to do with the TCC. It seems at least one other member has seen this same issue with your tune. The TC seems to lock in and out constantly when at highway speeds.

The third issue is the speedometer. Despite your reprogramming of the unit, the speedometer still reads around 5 mph below GPS speed when at highway speeds.

I was about ready to rebuild my transmission when I decided to try the stock tune again and all my problems went away.

[foosh]

How did the tune affect your mpg's?

[Trail X]

I noticed no change.

[foosh]

Oh man, i might be rethinking getting that tune then, i've heard it helps mpgs... guess its moving down on my mod list.

[Trail X]

Who knows, someone else may have a different experience, but I won't recommend it to anyone. There are other people like Mario who has had no problems with his tune.