motorman

anything you add to the truck like running boards, bug shields and sun visors that changes the designed air flow around the truck will kill the MPG. these trucks are put in a wind tunnel to get the best air flow(coefficient of drag) around the truck to get the best MPG. just raising the truck causing more air flow under the truck screwing up the CofD

BigBlackTruck2014

So, tonneau cover, good or bad for mpg?

motorman

I don't know for sure but there has been a TV show that showed that running with the tailgate down hurt the MPG. my 2013 Silverado has a add on lip on top of the tailgate to help air flow out the back of the truck. I remember my older Silverado with a slider back window had to be closed when hauling dirt as the air turbulence would cause the dirt to blow in the window if left open driving down the road

tech2

tonneau cover will increase mpg. That is why all hybrid pickups come from factory with a tonneau



driving with the tailgate up sets up a bubble of air in the box that forces air up and over the box...reducing drag. with the tailgate down the bubble doesn't set up and the air comes over the roof, down into the box and pushes down on the bumper creating drag. computer modelling has confirmed this.

Peragon

You may find the following links helpful.

Another thread discussing this subject


If you have any questions, give me a call. Rodger x71.

free88

Sounds to me like the cause of your MPG issue was being caused by the brake system. It is possible that one or more of the wheels was braking when it should not have been braking. This will cause the cruise control problem, very bad MPG, lock up on tap, etc. Im betting you also had one or more tires positions that wore unusually fast. This problem is a lot more common than you would think and it can happen to every make/model. It is very difficult to troubleshoot and usually ends up requiring the replacement of most of your brake system components to fix it. Very expensive and, of course, the dealer will try everything to get out of this. Not just Chevy, all of them. Ive personally known this to happen to two people. Took months to get fixed.

'03 Heavy Chevy

They probably thought the rings looked nice, neat, and pretty with the gaps lined up perfectly!


My Chevy 2500HD Crew cab 4x4 (automatic transmission) has never gotten anything better than 13 mpg hwy and about 8 - 9 mpg in the city....and thats with nothing being towed. Hauling my tractor dropped the hwy mpg down to about 10 (running about 65 mph). I joke with friends about how I get the best gas mileage out of my truck....I get up to cruising speed, roll up the windows, put it in neutral, turn the ignition off, and coast down hill!

Now that I'm not hauling anything with my truck, I've been thinking about purchasing a tuner to change the transmission shifting points, etc. From reading this thread, it looks like it will be money well spent and saved.....easily within one year.

Anyone have recommendations on a good tuner thats not over the top in pricing? My truck is stock everything so I'm not looking to put it on the race track

Thanks!

free88

Im an engineer, so I tend to value empirical evidence as opposed to gut feelings and the like.


The first thing you need to realize is that GM has already programmed and installed the key components for your truck to run at the optimal settings. It is already set to run at the best MPG across the largest range of speeds and tow/hauling conditions, while giving the most HP and torque across the largest range of RPMs, while giving you the maximum reliability, while giving you the least noise, while giving you the least vibration, while giving you...basically the best possible combination of every aspect of your trucks mechanical operation.


Having said that, any change in that profile (to include swapping parts such as intakes and exhaust, reprogramming, etc.) will alter that optimal setting. You may gain in one or more areas, but will lose in one or more others. For example, gain in MPG within a certain speed range, but lose HP and torque across the entire band. Or, get (perceived) better transmission shifting, but reduce the reliability of the transmission over time. In short, nothing is free.


Generally, however, people don't listen to reason and start with CAI and exhaust changes first, and this is where I recommend you begin. A CAI has been shown by most sources to very slightly increase MPG, HP and torque, while increasing noise only slightly. They are $150-$300 depending on brand, application, etc. Simple bolt-on that should take an hour to swap with simple tools.


The exhaust, well, that's still up for debate in my book. From all the evidence I have seen on various popular exhaust upgrades for our truck, I am not convinced that you will get an increase in MPG, HP or torque. However, you will get at the least a throatier exhaust sound and will get the nice chrome tips sticking out the side or back of your truck. I would only change the exhaust if it was time to change it anyway.

tech2

are you an automotive engineer?


cai are a complete waste. Most products out there are do not even isolate the intake air source from engine heat. On newer trucks the air flow calculations are so precise from factory that aftermarket cai are setting false dtc. The less restrictive filter cones don't meet filtering standards and end up gunking up the maf. its a $300 piece of jewellery.


10 year old 3/4 ton 4x4, 4sd trans and a 4.10 rear end...its a tank. Its kinda like buying a muscle car and then complaining about the gas mileage. You bought the wrong vehicle if that's your main concern...but when you need to pull something it can do it. maybe a new one with direct injection, afm, highway gears and 6sp trans....

'03 Heavy Chevy

I understand what your are saying. At this point, MPG is definitely most beneficial to me. I used to modify my vehicles more than stock options, but I stopped doing a lot of mods years ago. I'll put a new exhaust on whenever the stock one wears out.

Thanks for your input!


LOL to your muscle car comment. Back when I bought the truck I needed it for hauling heavy loads such as a tractor and cattle. It served its purpose, but now that I no longer haul heavy loads, I'm hoping to make one or two mods (i.e. tuning the computer) to have the transmission shift for less power but with better MPG. But, I've never messed with the truck computer, so just looking for any advice from those that have done it before and either liked it or disliked it.

I don't want to trade in my truck. Its the only truck I've owned since my son was born. Hoping to keep it and give it to him when he starts driving.

Thanks for your input!