Took the family on a 4Wheeling trip to Arizona a little while back. I stopped keeping track of my mileage a long time ago, but decided to keep track of it on this trip. I finally got around to calculating my gas mileage and I had some very interesting results:

Avg. mi/gal from San Francisco to Phoenix: ~13

Avg. mi/gal from Phoenix to San Francisco: ~17

There were only 2 differences in how the truck was setup between the two trips. 1) On the way down I had no rear bumper or hitch and on the way back I had a Sonoran Steel rear bumper. 2) On the way down I had the deck plate open and on the way back I had the deckplate closed (forgot to take it out after 3 days of wheeling).

Anyone have an explanation other than the obvious conclusion that the deck plate mod might actually hurt your gas mileage?

 

perhaos the drive there was more uphill, and the drive back was downhill? I know from Vegas to LA is uphill, and LA to vegas is down. Its ever so slight, but enough that I saw it on the gas reciepts. It also could have been that you were just excited to wheel!!

 

that makes sence to me

 

Brad, I know that I always get better mileage coming back from Phx. myself. I'm not sure of the elevation of Phx, but Bullhead is only about 500' above sea level. I have driven to both Phx. and Flag with my deckplate out and have always gotten better mileage coming back. I doubt the bumper made a difference, and I don't think it was the deckplate, although I might be wrong. I just know from my own experience that I always use more gas on the way to Phx or Flagstaff than on the way back....

 

Maybe it's the same when you fly from east coast to west, and then back. The one flight is always much quicker due to the wind.

 

i would agree that it could have been slightly uphill on the way there, or you were driving faster. i changed my driving style and gained 4 mpg highway from 14mpg up to 18 mpg

 

....you mean the jetstream was helping him on one of the legs?

The difference in milage could have been a number of things (steeper hills going one way, wind, outside temp, driving style, elevation, etc) so it might be tough to say definiatively since it wasn't exactly a controlled experiment.

 

wind is a huge factor in gas mileage on long trips- head in or at your back the entire way will be evident on your pocketbook...

 

I had thought about the wind. The thing is traveling through central CA you usually have the wind at your back when you're heading south. This would make the numbers even harder to explain.

I can eliminate driving style and weather as a factor as I was driving the entire time. Temps could have had an effect as we were traveling through the desert in the afternoon on the way there and in the morning on the way back. I doubt it would make a 4 mi/gal difference though.

Elevation change could definately be a factor that could make a difference and seems the most likely. But still, 4 mi/gal difference is huge and these numbers are fairly steady over the entirety of the one way trips.

 

Well.......I didn't want to say this, but my mileage suffers with my deckplate out, too.... Cuz I'm always flooring it to hear it go "vrooomm"!!!!
Seriously, Brad, next time I do Phx or Flag, I'll try to duplicate your experience. I'll drive there without the plate in, and then drive back with the plate in. I'll post my findings. (It will be in a couple of mos., though. My son doesn't have his next surgery untill the end of July.)

 

Yeah, I was that way when I first did the deckplate mod. It's been a few years now and that novelty has worn off so I don't think I was stomping the gas anymore than normal. Actually, I've been driving with it in for a few months straight now and sometimes I still stomp the gas, but now nothing happens. I think I'm going to take it out again. The 4Runner is feeling like a mule on the freeway, especially when passing.

You might have posted the story on here somewhere, but I'm sorry to hear that your son is having a surgery. I hope it's nothing serious.

 

Oh, no. Nothing seriously (relatively). He was born with a bilateral cleft lip and palate. His lip was fixed last May, and his soft palate was repaired in January, and he'll be going in for his hard palate. Prayerfully, it will be the last one for a while. He's a trooper, and he's doing great. (Although watching him eat bananas can be interesting.... ) Anyway, thanks for your thoughts, Brad. Here's a fairly recent pic of him on one of my mountainboards:

 

Interenesting question. I know that my MPG improves with my deckplate out.

 

Many people have noticed improved gas mileage immediately after doing the deckplate mod. However, the ECUs in our vehicles take time to learn and I wonder if the improvement decreases as the ECU adapts.

 

That's a possibility... If the computer "learns" the new amount of air, it might slowly adjust...hmmm. I wonder if you put the DP in for a while and then removed it if you would see a jump in mileage. It might be worth testing. Then again, I'm not a auto computer whiz, so......

 

When I did my deckplate my gas mileage was the same... I take it on/off every once in a while to see what works best... I get the same 170-180 miles and the pos gas light comes on...

 

I can say with it out sucks ass, with it in keeps some extra cash in the gas expense account. I hate that stupid noise anyway it doesnt seem to do a whole hell of alot just make noise and the more you push the more it makes .


Aaron

 

The deckplate mod simply reduces the resistance in the air intake by removing a couple of sharp turns in the air path. This does reduce the amount of horsepower scavenged from the engine, but it is an insignificant amount. It does not take much horsepower to move the total amount of air under normal cruising conditions and this mod just slightly improves on that.

I venture to say that the MPG gains from the deckplate mod are not measurable.

 

Ummm, the 3.4L as installed on the 4Runner & Tacoma is notoriously starved for air because of the elbow. The deckplate doesn't so much remove the path of resistance as it allows more air into the intake. It's been dyno proven to add 5-8hp.

 

Mid;

The mod could help the restricted air flow at the high end but more HP at full throttle doesn't get you better MPG.

At "normal cruising speeds" the mod won't make much difference.