Kennedy Custom Tunes MPG Gains for LLY's?

[Kennedy]

He could well see some benefit, but it's hard to say. Experience tells me to stay away from this one. The quest for improved fuel economy requires driver participation and understaning to be effective. At the very least he'll need to use cruise control to steady his speeds. Slowing down will also definitely help.

[mjammer]

Phil,

My first recommendation, besides obviouslt telling him to take it easier on the throttle, would be to install a set of guages. It becomes obvious when you are pushing the engine harder than necessary when you see that boost ramp up and the EGT's climb. Once he sees that, it might help him change his ways, then go for the custom tune. Also, I would hard wire his to the economy tow mode so he can't play with the performance setting because he would love that power too much to stay out of it

[ccurran]

As far as the DIC, yep, it is annoying but now that I know the trend numbers, at least I can do a quick calculation so I know where I stand.

Did you get a flash update from your dealer? I did in June 07 and since then, my DIC fuel used/mpg has been off by roughly the same amounts as you post... I run 100% stock. I've been back to the dealer numerous times since, but all they do is shrug shoulders and tell me that there is no new update from Chevy.

cheers & beers,
Chris

[mjammer]

No changes recently from the dealer. It hasn't been in since I got the Kennedy Tune put in and I have the OEM ECM module for when I do

[mjammer]

I thought I would post an update. Here is how the numbers are looking to date:

OEM Avg 15.482 MPG
Stock ECM & 265 Revos 14.522 MPG
Kennedy Tune & 265 Revos 16.172 MPG

I have ~4700 miles on the ECM to date and have been very please with the improved mileage and it will get up and go with much more gusto if you want it too, especially if you flip to the high perf tune.

The guages also really help me monitor the suttle changes when I am driving to help me find the acceptable speed vs. MPG throttle setting, especially when I am pulling a trailer. You can quickly see when you are pushing it harder by watching the boost and EGT temp climb.

[mjammer]

Time for another update. Here is how the numbers are looking to date:

OEM Avg 15.482 MPG
Stock ECM & 265 Revos 14.522 MPG
Kennedy Tune & 265 Revos 15.929 MPG

I have ~8800 miles on the ECM to date. I am still very happy with the tune as far as mileage gain and drivability. I periodically pull trailers and it is much smoother and easier with the tune. Of course, every now and then I just have to flip the switch to performance tune for a few miles and

[Kennedy]

Have you been able to duplicate the 22+ mpg on any other trips?

[mjammer]

Have you been able to duplicate the 22+ mpg on any other trips?

Nope, haven't been able to duplicate it but I also haven't been on a trip like that sinc either. I have only done one long, no trailer trip since then and it was in the dead of winter over Christmas to the upper peninsula of Michigan so it wasn't the best of weather. I did get 18 & 18.6 on that trip.

I am still seeing the DIC being off. I was looking at it recently and was wondering, is the tank size stored in the ECM ans it seems like the Fuel Remaining is off from reality as if it thinks it has a 30 gallon tank vs 34 or something.

Mark

[mjammer]

Have you been able to duplicate the 22+ mpg on any other trips?

John,

I just got back from a trip up to Boundary Waters (Ely, MN) and got great mileage. Over 4 fill-ups and 1575 miles I averaged 20.98 mpg. This was with 5 people and gear in the truck and running at to a few MPH over the speed limit most the time.

Mark

[mjammer]

Just another update after several summer vacations with the truck including hauling Jet Ski trailers and Boy Scout Trailers around.

OEM Avg 15.482 MPG
Stock ECM & 265 Revos 14.522 MPG
Kennedy Tune & 265 Revos 16.251 MPG

This is over 14K miles now with the ECM.

Nice job John! Thanks

[mjammer]

Its been awhile since i did an update. The tune is still going strong.

OEM Avg 15.482 MPG
Stock ECM & 265 Revos 14.522 MPG
Kennedy Tune & 265 Revos 16.146 MPG

This is almost 21K miles now with the ECM.

About time for some new tires. Will probably get Michilen LTX M/S II's in 235/85R16's to see if that bumps the mileage a little more.

[gimpyhauler]

'07 Sierra Classic, Duramax. I don't have the full data yet but I have some observations. I haven't put on enough miles yet to truly establish my fuel savings. BUT, it appears I'm getting better mileage, so far. Stick it on level 4 (Holy S_it setting) and put your foot down, it's a scary level of power. I leave it on level 2 normally for better mileage and am very pleased.

[Kennedy]

Fresh change of Delvac 1, and bypass filter at 91k on odometer. Previous change was 68k. Loyal WI to Pierre SD via I90 running at 5-6mph over posted 70 and 75mph speed limits. As usual I had across 20mpg going until I hit the MN line. The speed, the climb up from the River, and the following open terrain and wind hammered me down to where we were down to 17mpg by the time we hit Pierre. I know if I would slow down it would come up dramatically, but with a 10+ hr drive I just want it to end. Besides we'll make it up on the trip home running with the wind right?

Trip home saw Easterly winds. MPG never got a chance to recover much. Sat at 17 pretty much all the way. Once in WI and running under 65mph it started coming back and ended up at 17.4 for the trip.

With 1200 miles on the oil change pull the stick and it still looks like honey. I have a large tune at my disposal with a flip of the switch, but seldom use it these days. A modest 50HP tune gets the call 99% of the time. DIC fuel used and economy is quite accurate with this tune, smoke is non esxistent in most all cases, and it's just nice to drive...