2014 GMC Sierra 1500 5.3L MPG Tune

[Zexy Magician]

2014 Sierra 1500 5.3L 3.42 gears 4x4 w/50k miles
MPG booster tune applied, no transmission tune. No other changes.

I cannot believe I am saying this, but I genuinely like the mpg booster tune for this truck.

The problem I had with the other tunes was that the truck always had to rev up to 2k rpm just to get moving. The mpg tune shifts much lower at around 1.5k rpms when driving around town and it's almost effortless how quick and smooth the truck gets up to speed.

I also noticed that the transmission hunts for gears much less with this tune. It is much more confident with gear selection and holds it longer. I need to do a bit more driving, but I think the issues I had with the transmission hunting for gears and randomly shifting hard has been eliminated with this tune. Even the other canned tunes had sloppy transmission shifts and never fixed the stock problems for me.

Obviously, this tune is less fun compared to the others and will need much more effort to get moving if hauling. For those that commute with this truck, this tune is great. No idea if it improves mpg's yet, but I don't really care at this point as the driveability is so much better.

One question I do have: Does the mpg tune change AFM to be more aggressive/hold longer?

[mikel]

Yes, AFM will engage more often with the MPG tune.

[Zexy Magician]

Yes, AFM will engage more often with the MPG tune.

Thanks! Now how does WOT on the MPG tune compare to stock? Is it designed to shift sooner or use less fuel throughout the power band?

Also, how does tow mode work with this tune? Could you haul light loads so long as tow mode is engaged?

[06MonteSS]

you said that you did not install a transmission tune.. . so, then there are no changes made to the tranny shifting.. the tranny is stock..

and if you DID install a tranny tune, the tranny tune only changes how quick it shifts, and shift pressure/firmness, that's it... it does NOT change any shift points at all with the preset tranny tunes.

You'd just use the tow/haul button on the dash like you normally would. That just tells the transmission to use different shifting settings, that's all it does. The engine tune does not and can not change at all, the engine tune stays the same no matter what mode you're in.

[Zexy Magician]

you said that you did not install a transmission tune.. . so, then there are no changes made to the tranny shifting.. the tranny is stock..

and if you DID install a tranny tune, the tranny tune only changes how quick it shifts, and shift pressure/firmness, that's it... it does NOT change any shift points at all with the preset tranny tunes.

You'd just use the tow/haul button on the dash like you normally would. That just tells the transmission to use different shifting settings, that's all it does. The engine tune does not and can not change at all, the engine tune stays the same no matter what mode you're in.

Did not install a tranny tune, only selected the MPG tune. No other changes made.

There is definitely something different with the way the transmission shifts with stock vs canned on my truck.

On the canned tranny tunes, normal driving with light acceleration would shift up at around 2000 rpms through just about every gear and it feels like it does not need to rev that high.

Now with the stock tranny tune, with the same light acceleration, I rarely see revs higher than 1500 rpms. The stock tranny tune shifts quite early in comparison to the canned tranny tunes. Not sure why this is, but it is definitely there. I may need to capture some recordings.

I prefer the stock transmission shift points, but would like to have the firm shift feel and shift speed of the canned.

[Zexy Magician]

Updated my response above.

Shift points are definitely different between stock vs canned transmission tunes on my truck. Stock shifts low, but keeps the truck moving. Canned shifts pretty high (around 2k RPM consistently). Has this been addressed before?

[Zexy Magician]

Video comparison. Both videos recorded on the same, flat road light on the gas. Both using the 87 canned tune.

Stock Transmission tune
https://youtu.be/-eq7ys0bXJs


Firm transmission tune
https://youtu.be/ltRqMI-mOfo

[mikel]

sometimes the added throttle boost can cause shift points to hold a little longer, are you adjusting that when loading the tune?

[Zexy Magician]

sometimes the added throttle boost can cause shift points to hold a little longer, are you adjusting that when loading the tune?

I had no additional throttle boost or any other changes applied with the results described above. Although, I tried out throttle boost this morning and found some strange results...

Still using the stock transmission tune, I added 15% throttle boost and found it makes the truck shift earlier. Keep in mind, this is with the mpg tune applied, no canned TCM tunes applied. Not sure why this happens, but it does!

I am curious as to how 15% throttle boost will affect the firm shift TCM tune. If adding throttle boost somehow forces the transmission to shift closer to stock, I'd be all for it.

I have read many posts here of others hating the stock 2014 shift points and I have no idea why. Stock simply shifts better for me and the engine accelerates effortlessly. As for stock shift quality, that's another story. The firm shift tune does have better shift quality, just worse shift points under light acceleration.


To recap my experience with the stock vs firm transmission tunes:

Stock shift points are where I expect them to be. Revs are low (but not too low) and the truck accelerates without issue. Can hardly hear the engine as it accelerates. Shifts are slower than the firm tune, but not by much.

Firm tune shift points are higher. What I find annoying is that I have to give the truck MORE gas at around 45 mph just for it to shift up and to keep accelerating. Doesn't feel as effortless while driving around town. Although, shift quality is improved (faster, firmer, giggity).

Next step: Going to try the firm shift tune with 15% throttle boost applied. I am maintaining the MPG booster tune throughout all of this as my truck seems to be the "golden child" with having no AFM issues to report.

[Zexy Magician]

Next step: Going to try the firm shift tune with 15% throttle boost applied. I am maintaining the MPG booster tune throughout all of this as my truck seems to be the "golden child" with having no AFM issues to report.

Yup, not a fan of firm shift + throttle boost. Going to stick with the stock transmission tune for now, might play around with shift pressures on that.

MPG booster will stay. If I stick to 100% highway, I get mileage upwards of 24mpg's locked in at 65mph. 5.3L 4x4, by the way. It doesn't seem to help that much when city driving is involved.

[DrDan]

I have a 2015 Silverado, same set up as yours. Not a fan of the firm shift either. I wanted to disable AFM, one of the main reasons I bought my i2, and to get the transmission to shift better. I bought a V8 and I want a V8.

Although they say the firm shift does not raise shift points, I'll have to agree with you that it does.
I used the firm shift tune, and also tried the hard shift tune, didn't see much difference between the two.
Under light load in town around 30 mph the firm shift (3-4 shift) wouldn't come on until about the 33-34 range.
Stock shift would already be there, but was mushy up through the gears.

Under modify stock tune.
I use the stock engine tune with the AFM disabled, and on the transmission, raise the pressures up to 10%, see if that doesn't help.
I also turned torque management off.
Now it's in 4th gear at 30mph running about 1,000 rpm, nice and easy.
It will run up through the gears nice and smooth, and also you can feel the difference in shift quality.
It also does pretty good when you need to get on it pulling out onto a busy highway.
Get about 17mpg in town and around 23mpg on the highway.

Just thought I would throw my 2 cents in.

[Zexy Magician]

I have a 2015 Silverado, same set up as yours. Not a fan of the firm shift either. I wanted to disable AFM, one of the main reasons I bought my i2, and to get the transmission to shift better. I bought a V8 and I want a V8.

Although they say the firm shift does not raise shift points, I'll have to agree with you that it does.
I used the firm shift tune, and also tried the hard shift tune, didn't see much difference between the two.
Under light load in town around 30 mph the firm shift (3-4 shift) wouldn't come on until about the 33-34 range.
Stock shift would already be there, but was mushy up through the gears.

Under modify stock tune.
I use the stock engine tune with the AFM disabled, and on the transmission, raise the pressures up to 10%, see if that doesn't help.
I also turned torque management off.
Now it's in 4th gear at 30mph running about 1,000 rpm, nice and easy.
It will run up through the gears nice and smooth, and also you can feel the difference in shift quality.
It also does pretty good when you need to get on it pulling out onto a busy highway.
Get about 17mpg in town and around 23mpg on the highway.

Just thought I would throw my 2 cents in.

Yup, exactly as described on the 3-4 shift at about 33 mph. Also, the 4-5 at 43mph. The diablo tcm tune should definitely shift up earlier as the rpms hang north of 2k rpms until that speed is achieved.

Makes me wonder if the shift tune is for the 3.08 axle? I have the 3.42, curious as to what you have.

I currently have stock shift with the shift pressures set up as follows:

1-2: 2%
2-3: 2%
3-4: 10%
4-5: 10%
5-6: 10%

I may bump up the 1-2 and 2-3 to 3%. I dialed them back down from 4% as they were still, occasionally, shifting harsh with a noticeable jump. Very random, but still annoying.

Curious if you use throttle boost at all. Thanks for the reply!

[DrDan]

My sticker says it has the 3.08, don't use any throttle boost, I do have the torque management turned off.
It's not perfect, I still play around with it when I'm bored, but I think for me it's better than stock & the firm shift tune?
I've made a living as a mechanic since 1979. Used to work in a gm dealership. Moved on to heavy equipment in 1988.
I'm pretty far out of touch with how they do things now, all computer controlled, lots of variables.
Back in the old days we used to adjust shift points by road speed at minimum throttle with a vacuum modulator and a governor
Governor pressure made the transmission upshift, modulator pressure was on the other side to make it downshift, or hold it in a lower gear according to engine vacuum. Man how time flies. Now you can just sit in the drivers seat to adjust, don't even have to get dirty any more.
Computers are taking over in the big truck too.

[DrDan]

Well yesterday after my last post, I was kinda bored, so I got my i2 out, updated it ( I was surprised to see so many since my last update) and took it out and plugged it into my truck, and just for shits and giggles installed the mpg tune with 15% throttle boost, AFM on. Left the transmission alone, with my stock modified shift pressures of 10%, and took it for a drive. Did a little town and country and some highway. Hated it. Transmission was weird acting, didn't seem to have as much zip, and shifting was not as smooth, actually all over the place. Ran about 20 miles and took it back to the garage. Turned the throttle boost back to 0, and drove it again for a little bit maybe 10 miles or so, it was better, but it didn't seem it was better than what I had to begin with, so back to the garage I went. Took the mpg tune out and installed the regular 87 octane tune, AFM off, and 0 throttle boost, left the transmission alone, took it back out for a drive and it seemed much better. Yesterday was a cold rainy crappy day, probably not a good day for tuning. Anyway, today (sunny and about 52 degrees) I put about 60 miles on, combination of town and highway, and I have to say I think it was really a lot better than what I started with, seems to have more power. Transmission shifting is back to where it was and I like that. I'm going to leave it this way and drive it to see how it does on gas. I read somewhere in here that you need to put some miles a new tune to let it learn how you drive or something along that line. Maybe I didn't give Saturdays test enough miles?
So I think that throttle boost may have something to do with how well the transmission does?
It might help those who don't care about fuel economy and just want to get on it all the time?
Just my opinion...I could be wrong.
FYI my truck is a single cab, long bed. That may be the reason I do a little better on fuel mileage? Lighter weight?
I do have MBRP catback dual exhaust that sound real good with the AFM turned off, I don't think it does anything for performance.
My 2 seat sports car just happens to be a truck

[Zexy Magician]

It's kind of interesting how these tunes seem to behave differently on these trucks. From combing the forums, everyone has had a unique experience.

What most people can agree on, though, is that the canned transmission tunes for these trucks is not very good. The firm and hard tunes rev and shifts like a 4 cylinder, have inconsistent gear shift pressures, and have slow/erratic shifting...

As for the engines tunes, I've gone between the MPG and 87 recently. No significant differences noticed on my end except that, apparently, the MPG tune holds AFM longer (which I do not notice).

I'm going to max out throttle boost and drive around for a bit. If it has a detrimental affect on the stock transmission shift points, I will leave at 0%

Next, I may play around with AFM a bit more. When I first turned it off, I didn't notice any significant difference. I feel like if AFM is not noticed on stock, then disabling it will not do much. Once the truck is out of warranty, though, I will be disabling it.