07 Silverado Gas Mileage Help

sfd305 · April 20, 2008

I have a 2007 Silverado Crew 4x4 with the 5.3L and AFM. I am wanting the best options to get better fuel mileage from my truck. I have looked at a CAI, Flowmaster Series 50 and TBS. Am I am on the right track or is there something else I can do to it. I use the truck as a daily driver and also pull a boat and camper with it if that helps any. Thanks.

black00chev · April 20, 2008

you can try spending a bunch of money on exhaust, CAI, tune and stuff like that but it most likely wont help the mpg that much... if anything just dont push it over 2k when accelerating and keep it under 70mph

Zembonez · April 20, 2008

You don't mention what you are getting now. 14 - 17 is about all you can really expect. We have a few miracle worker members that claim to get 20 but I am not sure what they are smoking. It sure as hell isn't their tires!

Norman · April 20, 2008

I can get 22-23 mpg on the highway at cruising speeds around 65-70 mph, but certainly not in the city in usual driving manner. I averaged exactly 15.5 mpg overall in the course of exactly 1 year. I have a 2007 NBS Sierra Regular cab with a 4.8L and 3.23 gears. If you're getting 16 mpg as an overall average with an extended cab and higher gears, I'd like to know how.

black00chev · April 20, 2008

i usually get between 15-17mpg with the exact truck seen in my sig and in my garage.

omegafiler · April 20, 2008

Yeah, what they said. But if you're bored, you could search the forum for tons of posts about MPG.

Texsrt4 · April 20, 2008

i am getting an average of more than 24mpg on my DoD vehicle. the secret is actually in the tuning. you will need to find someone with hptuners and adjust the DoD engagement and timing maps.

sfd305 · April 21, 2008

Well I am getting 16.7 on the DIC with combo city/hwy driving so I guess there is not much hope. I have a crew with 3.73 gears so I guess I can't complain too much. I sold my 98 Extended cab with a 350 and 230K miles on it and was still getting about that too figured with the improvements and such there would be a way to squeeze a little more out of the new one. Oh well thanks for the advice.

sfd305 · April 21, 2008

Will any of those improvements help when towing in the mountains?

Texsrt4 · April 22, 2008

Well I am getting 16.7 on the DIC with combo city/hwy driving so I guess there is not much hope. I have a crew with 3.73 gears so I guess I can't complain too much. I sold my 98 Extended cab with a 350 and 230K miles on it and was still getting about that too figured with the improvements and such there would be a way to squeeze a little more out of the new one. Oh well thanks for the advice.

i too have the crew cab 3.73 combo. trust me, its all in the software. however, there arnt any handheld programmers that will update what you want. you will need a custom tune. check out hptuners.com. on their forum, we have started to pool information about tuning DoD setups. when it comes to teh mountains, keep you foot out of it. accelerate slowly and if you need to slow down get off the gas and let the vehicle coast. when you are off the gas the vehicle goes into DFCO or decel fuel cut off. this means the car is using no fuel as it is slowing down. it can make a huge difference...but get a tune. trust me

Gonnagetem · April 23, 2008

I have an 07 CC 5.3 with 3.73's

A touch under 6k miles. Gibson single with ss headers 18.1 mpg actual, computer tells me its 18.2

None of that is highway dirving, but I don't think that it would vary much. Probally go down a little at high speeds.

stlavsa · April 23, 2008

texsrt4 is rightt about the software. Dont botter putting exhaust and intakes on in effore for mileage. You will most likely lose mileage becaue they make sounds that you like and you end up giving it more throttle to hear the sounds!. All your gonna do there is blow a ton of dough on stuff that wont even really make more power unless you get it tuned anyway, SOOOO tuning is the way to go.

As far as I can tell the problem with buying a "tuner" or tune or chip or whatever is that these tunes are made to increase power, and they also claim better MPG at times but I would like to know how.

HP is made through fuel, It takes a certain amount of fuel to make 300 hp, whether its in a 4 cyl or 8 cylinder, if you useing the same fuel its gonna take about the same amount. Iefficiency comes into play here but we are speaking generally)

SOOO anything thats claiming to add HP is going to generally do so by ADDing fuel. Usually these tunes bump up the timing maps, and then if there is more HP to be made by adding timing, they have to add more fuel to the fuel maps in order to compensate for the leaner condition created by the increased timing.

Your truck is FUEL INJECTED

The fuel going to your truck is controlled by a basemap of fuel and timing, and in closed loop it runs off of those tables, and is slightly corrected through input from various sensor like MAP, O2, etc.

For the most part, the amount of fuel supplied through the injectors is decided by the amount in whatever "cell" your truck happens to be in on the fuel map. So if you have an aftermarket intake, it is still going to be supplying the amount of fuel denoted by the cell that its taking its reading from. The cells or portions of the map it is reading from is decided by your ecu based off load, which is calculated by speed, mani pressure, stoich readings, throttle % etc.

For this reason, driving light footed will save you the most gas, because the ECU will be running on the lower cells of the fuel map, less load=less fuel.

IF you have any hope of modifying the truck for more MPG, your only real option is through ECU tuning.

I havent looked into it with this truck yet, but I definately think it can be done. This would be done by lowering the amount of fuel delivered in the fuel maps, This will however create a lean condition which is unsafe, and pulling total timing from the timing map will be needed to help correct this.

THeres a couple problems with this though, #1 less timing = less power, but I dont feel these trucks are under poowered so losing a few hp for a couple MPG may be worth it. (thats your judgement call, i say it is worth it) There is a limit on the amount of fuel and timing you can pull, because there will be detonation, and pulling too much timing can result in very high EGTS or exhaust gas temperatures (aka melt your shit).

Another way to increase MPG is to get the motor running in 4cylinder mode more with the active fuel management. Its safe to assume that the ecu puts the 5.3 into 4cyl mode with readings based off of Load aswell. Therefore, you could tweek the fuel management to kick on at a little bit of a higher load reading and get more use out of it. (You dont want to set it too high though, because you could over work the engine in 4cyl mode, these trucks are HEAVY!)

sfd305 · April 23, 2008

Thanks for the tips, I have read a lot of the threads giving pros and cons of HH vs custom tunes. My biggest thing is I may be running around town today and then back up to the boat tomorrow to go to the lake and then Friday may hook up to my camper to go somewhere for the weekend. I live in the foothills of SC (read lots of hills) the AFM kicks in going down hills and coming to a stop but other than that it really does not stay on much so there may be an option to increase the load limit that it kicks on.

I have had the advise of keeping my foot out of it which 90% of the time I take off from a stop and don't let it get about 2000 RPM when I'm not pulling so I don't think I could drive much more conservative without running the chance of getting run over! My biggest problem is I usually have to get on the interstate anywhere I go and my exit has a good hill I have to pull when merging into traffic so not a chance of taking it easy here a lot of the time.

What is the best most user friendly HH tuner on the market. I know I am going to open a can of worms because everybody has the best one but still would like to hear some opinions on what is the easiest to use and ease of changing the programming depending on what I am needing out of my truck on any given day.

C & A s Dad · April 23, 2008

You asked what is the "best most user friendly HH unit"

I have done a ton of research on this because I am sort of in the same boat you are. My Yuk XL is my Wife's daily driver and I do not want any issues to pop up from a tune. In my research I have found the following:

The Hypertech Max Energy is the most conservative in the terms of producing power and tq but it is also very user friendly and from all indications, the safest. Their unit has two tunes with both of them safe for towing. Their dyno charts show the power and tq comes in the low to mid RPM range. They have an excellent website and their dyno sheets are very complete. Their customer service is also terrific and they spent about 10 to 15 mins with me on the tel and sent me some additional info.

The Superchips Flash Paq seems to be next in line. My research seems to indicate it will produce mor power and tq but seems to come with some reports of issues. Not many. Their premium tune is not recommended for towing and for this reason they have a separate tune that is for towing. It is much more conservative in the power and tq ratings. Their dyno sheets indicate the power and tq comes in very high in the rpm range. I contacted them as well and was treated like I was interrupting their day.

Diablo offers the most power and versatility but seems to come with the most reported issues. Again, the power comes in very high in the rpms.

Bullydog Triple dog gas seems like a nice unit but their dyno sheet does not show anything below 3400 rpms. I also cannot find anyone willing to admit they have one.

I also have a contact who sells three of the units listed above. He had nothing negative to say about any of them. He did say that the only one that customers have every reported any MPG increases with was the Hypertech.

For my towing needs, I am going to try the Hypertech. Most people with the unit are happy but they also tell you not to look for any tremendous gains in power or mpg. Another GM truck forum has an on going poll on HH units and Hypertech as over 50% of the votes.

Please know my comments and research certainly are not "scientific". I just tend to overresearch something before I buy it. Tuning is like most everything, there is not a one unit fits all and for this reason there are many to choose from.

Sorry for the length of this but hopefully it will be helpful.

pennzoil29 · April 23, 2008

You don't mention what you are getting now. 14 - 17 is about all you can really expect. We have a few miracle worker members that claim to get 20 but I am not sure what they are smoking. It sure as hell isn't their tires!