THinking about undoing some mods on The Beast. Thoughts? - Gas Savers

**Jay2TheRescue** · 06-10-2009, 09:53 PM

I've been thinking about undoing some mods I've done on The Beast. I don't seem to be getting anywhere close to last summer's mileage, even though I am more skilled and I have a Scangauge to help me. Last year I was pulling about 15-16 MPG in city traffic. Right now I'm pulling 12-13 and I'm not even using the a/c much. I'm thinking about starting with the extended airdam. I'm thinking maybe the increased frontal area is (maybe) hurting me more than just letting the air go under the truck. Since the truck is a Z71 it has the premium off road package with skid plates from the factory. Maybe the skid plates act as a partial belly pan?

-Jay

theclencher · 06-10-2009, 09:57 PM

OK If you were getting 15-16 with mods, and now you get 12-13, and you haven't changed any of the mods since you recorded 15-16, there is something else going on. Environment, state of tune, whatever. I predict pulling mods off, if you proved they worked last year, will not return you to 15-16. That just doesn't make sense. Of course, if the mods were never proven to work in the first place, you have nothing to lose.

**Jay2TheRescue** · 06-10-2009, 10:00 PM

I was getting that before all the mods were installed... As far as "state of tune" is concerned, I had a full dealer service less than 10,000 miles ago. Flush & fill everything, new ignition parts, etc. Plus last fall when I had my torque converter replaced I had the tranny refilled with synthetic ATF. I should be able to do better than last year's mileage.

GasUser · 06-10-2009, 10:10 PM

What if you just changed the plugs and then run it for a week and see what happens?

What if it is the gas......like all of a sudden they are putting in more ethanol or something?

Try running a bottle of Techron Fuel system cleaner through it. And check the throttle body to be sure it is clean. Check the air filter and pcv.

Do you have a scan gauge and if so you are running closed loop right?

That's all I can think of at the moment as I am having a brain cramp. I am sure you did all this.

theclencher · 06-10-2009, 11:30 PM

"I was getting that before all the mods were installed... "

AHA, the truth comes out! Pull em off then; can't hurt.

Also just cuz it's fresh from the dealer doesn't guarantee they did it right, or caught every problem. Did the fe drop right after mods install? Well, if the mods were never evaluated we just won't know much of anything til you pull em off, or do a-b-a.

**Jay2TheRescue** · 06-11-2009, 05:11 AM

The FE started falling as fall came. I chalked it up to winter blend gasoline and cold temps. I fully expected it to rebound in the spring, but aside from a decent tank here & there I'm not getting the results I expected so far this year. I figure I'd start with my most questionable mod, the extended airdam. I was never totally convinced it ever worked, and the more I think about it, because I have the factory installed skid plates under the truck that the underside may not be as messy as I thought, and the increased frontal area may be hurting me.

BEEF · 06-11-2009, 05:27 AM

could it also be the gas you are buying?

it seems to me that there is a lot more E-10 out there now than there was last year. E-10 kills my mileage.

**Jay2TheRescue** · 06-11-2009, 05:50 AM

I live in an area that was E-10 mandated. Last year I was buying as much fuel as I could from an Exxon (Catlett, Va) on my way to visit my parents because for some reason I got unexplainably good mileage on fuel from that station. I have not been getting the same boost in mileage this year when buying fuel there. Maybe they are E10 now? My guess was that they were selling real gasoline as they didn't even have vapor recovery installed on their pumps. Certainly if E10 was mandated in that area, so would vapor recovery, right?

**theholycow** · 06-11-2009, 07:22 AM

What about the transmission? What if something about the transmission or installation is to blame?

I'd still start with taking off the mods, though.

**Jay2TheRescue** · 06-11-2009, 07:43 AM

The only thing that was done to the transmission was replace the TC, then flush & fill with synthetic. They didn't open the tranny.

**theholycow** · 06-11-2009, 07:45 AM

Maybe the new TC is different or not hooked up right? I'm sure you'd notice if it was very different and not locking or something, but maybe...

**Jay2TheRescue** · 06-11-2009, 08:40 AM

Well, being a PWM controlled TC, you're not supposed to be able to feel when its locked or not. However, being OBDII the TC is monitored, and if its supposed to be locked, and the computer detects that its not, the CEL should be lit.

Jetta90GL · 06-11-2009, 05:51 PM

Most of our stations are E10. I used to have one citgo station that sold 100% gas, which gave me an extra 2 mpg. In Wisconsin we don't have vapor recovery on any of our pumps, except in the areas in and around Milwaukee.