K&N CAI decrease in MPG? & How to get more MPG overall

[edjosh3rd]

Hello. I'll just be honest where I am going with this. I was on the quest to get a different vehicle because of overall poor MPG. (Now I know that these things are not aerodynamic by any means), but with gas prices the way they are. I wanted something that offered better. I was unable to get a loan for another vehicle that I wanted that offered better fuel economy. I have just under 8 grand left to pay on the Trailblazer. So what I am going to do is pay the rest of it off, and then go from there and trade it in. But since the price of gas isn't going to get much better I want to save as much MPG as possible. I have around 126,690 miles on it right now so its not due for any other major maintence for awhile yet. So here is what I am going to do for hopefully better MPG:
1. I am going to remove my K&N CAI and put the stock back in because I am certainly positive that I have been getting worse MPG because of the K&N CAI and I live in a colder part of the world, so colder air means more fuel needs to be dumped in right?. Any suggestions for a disposable air filter that gets great MPG as well?
2. I am going to take the whole roof rack off.
3. Dump in some Techron
4. Check my tire pressure (question for you guys, what is the optimal pressure for the best mileage? I know the door says 30 front, 35 rear. I have the "Goodyear SilentArmor Tires". The sidewall on those tires says a Max pressure of 50. So what would be the most fuel efficent psi for these tires both front and rear?) I have had several friends tell me that my driver side front tire looks a bit flat at times, and I check it when it is cold and it is around 30PSI. So maybe I should have put a higher pressure in these anyway.
5. ? anything else you guys can suggest to me for more MPG, I've grown to the point where I don't care about the extra horsepower anymore, I just want better MPG. And that was my first mistake when buying the TB to expect good MPG oh well, live and learn. BTW guys, I got the PCM tuned for the K&N CAI, when I install the stock air intake will that be OK? Because I really don't want to send the PCM in again just because of the OEM stock intake change over. Thanks guys!

 

[jham]

First of all welcome to the nation. What kind of Mpg's are you getting?

 

[edjosh3rd]

First of all welcome to the nation. What kind of Mpg's are you getting?

In the winter I average anywhere around 14-16. In the summer I can average anywhere from 16-17. There is a gas station around me that still carries 100% 87Octane gas, and I only fill up there. I had a "Coustic amp with subwoofer" but I took it out because I noticed a big drop in MPG's (my guess because of the extra electrical load is using alot more fuel), with the amp I averaged around 14MPG now its back up to around 16

 

[edjosh3rd]

Does 35PSI all the way around sound good to you all? If I don't get any more reply's I will try that and get back to you all and see what my results are for my MPG's

 

[Wooluf1952]

Welcome

In case you haven't heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/

I would go to at least 40 lbs in the tires, possibly 45. My General Grabbers are rated for 44 lbs max and I run them at 38.

I haven't heard of anyone getting better mileage from a CAI.

The only change was because they drove harder to hear the CAI sound.

 

[CaptainXL]

1. I am going to remove my K&N CAI and put the stock back in because I am certainly positive that I have been getting worse MPG because of the K&N CAI and I live in a colder part of the world, so colder air means more fuel needs to be dumped in right?.

Yes, colder air means the engine needs more fuel but a K&N CAI would not be the cause of worse MPG.

4. Check my tire pressure (question for you guys, what is the optimal pressure for the best mileage? I know the door says 30 front, 35 rear. I have the "Goodyear SilentArmor Tires". The sidewall on those tires says a Max pressure of 50. So what would be the most fuel efficent psi for these tires both front and rear?) I have had several friends tell me that my driver side front tire looks a bit flat at times, and I check it when it is cold and it is around 30PSI. So maybe I should have put a higher pressure in these anyway.

The sidewall max pressure is cold. The max pressure ratings are federally mandated. For type P passenger tires there are 3 grades, 35psi, 44psi, and 51psi. If you want the most MPG then you would choose 50 PSI. However there are increasing risks as the pressure goes up. Higher damage/puncture rate, increased center tread wear, poor steering, reduced stopping distance...etc.

 

[03envoy]

Yes, colder air means the engine needs more fuel but a K&N CAI would not be the cause of worse MPG.

But, Just A tip on Better MPG possibly Efans...... But, I wouldnt worry about sending your Pcm back. You could gut the air box, or just leave it alone. You may just run a little rich.. Without the K&N that is.

 

[MDBT]

With the tiny margins of fuel economy we're talking about here having proper tire pressures and a lighter foot will go a long way.

Passenger vehicles are rarely designed to run at their maximum tire pressure, stay way clear of 44-45 psi. 35 is a good start, perhaps a chalk test on the tire might help you find the proper pressure if you cannot find it documented from the tire or vehicle manufacturer.

 

[03envoy]

With the tiny margins of fuel economy we're talking about here having proper tire pressures and a lighter foot will go a long way.

Passenger vehicles are rarely designed to run at their maximum tire pressure, stay way clear of 44-45 psi. 35 is a good start, perhaps a chalk test on the tire might help you find the proper pressure if you cannot find it documented from the tire or vehicle manufacturer.

But, The little things can help. Well The OP is saying he can notice the MPG Decreasex with the K&N..... So it must be noticable to some extent. Depending if he is calculating it or not.

Also, Your tires have a Somewhat Aggresive pattern compared to a non-AT tire. Unless they are needed, You may want to switch to something else. Just my

 

[Mooseman]

But, Just A tip on Better MPG possibly Efans......

I can testify to the efans gaining at least 2 MPG with that alone. But, my old EV fan could have been dying and sucking more gas than it normally would. And then I made a home brew CAI hooked up to the stock airbox and I also noticed that my gas consumption dropped. No numbers but I think it's just a right foot reaction more than anything . I will be going back to the resonator.

 

[bmartinezx3]

I had a "Coustic amp with subwoofer" but I took it out because I noticed a big drop in MPG's (my guess because of the extra electrical load is using alot more fuel), with the amp I averaged around 14MPG now its back up to around 16

does anyone out there know if this is true? will subs/extra audio system make a mpg difference? i have a somewhat small system(2 12's) and i get HORRIBLE gas mileage. i bet alot has to do with me driving bad, but if my system is costing me precious gas then i have to rethink having them.

 

[edjosh3rd]

does anyone out there know if this is true? will subs/extra audio system make a mpg difference? i have a somewhat small system(2 12's) and i get HORRIBLE gas mileage. i bet alot has to do with me driving bad, but if my system is costing me precious gas then i have to rethink having them.

So my conclusion is: I have pumped all 4 tires to 42PSI and took the roof rack off and put the original air intake system back in, removed my amp and subs, and put my stock radio back in, Now I am averaging around 23-24MPG :wootwoot: :wootwoot: So between all of these things that I have done it has greatly improved my gas mileage by adding an additional 7+MPG. So needless to say that I am much happier now. Thanks to everyone for your suggestions

 

[Mooseman]

That is very interesting. Definitely will give these a try (minus the subs, don't have any )