Okay IÆm not a big car person. But I was getting some pretty poor Gas Mileage (about 14.7 mpg city and about 18.1 mpg on the Highway.) And I started thinking about what could cause this, the 1st thing that came to mind was the engine getting to much air. (Aka cone filters have been known to cause this) But there was 1 prob. I don't have a cone filter I've got a K&N Drop in (which by the really didn't show any noticeable diff in mpg OR HP. and yes I did reset the CPU <img src="/forums/images/graemlins/wink.gif" alt="" /> ). So that couldn't be it. Then I started to think if too much air = less mpg what about too little air. Shouldn't that cause the same thing?

So I popped the hood and started to look at the stock air box. And thought about trying to drill some extra holes in it to allow more air in it. But that would be hard to cover up and jackass service manger by me would probably tell me my warranty was void or any problems I'd had where linked back to the mod'ed air box <img src="/forums/images/graemlins/rolleyes.gif" alt="" />. So any thing I wanted to do had be reversible. So I started tried by just
Removing the plastic part of the air intake thatÆs inside the driverÆs side fender (which mind you faces up to the top of the fender and just about cuts off EZ to get at fresh air to feed into the air box). I removed it and reset the CPU and drove it for 3 weeks. I noticed a 1.2-2 mpg (city and highway) gain.

Now this brought me up to the right mpg my RS should be getting. YAY. But I thought what if I opened it up a little more. Like a lot! So I shelled out some cash and tried a cone filter from K&N. Removed my stock box, made a simple heat shield outta some sheet aluminum and repeated the same thing. Reset the CPU and drove for 3 weeks. There was a drop in mpg over my original MPG by about 0.7. (I was bummed and returned the air filter; Thanx goes out to the nice people at auto zone for allowing me to return it!!!

I again repeated my 1st experiment with the stock box with out the inner fender part of the intake. Same results about 1.2-2 mpg gain over my original mpg. YAY!

So I thought I'd try to do some thing halfway in the middle.
I left in the stock air box but removed the front tube part of it. (If you take out the air box you'll see its try 3 pieces. The Lid, The Box, and an attached elbow L shaped tub riveted to the Box.) I removed (CUT) off the riveted and put back in the box. But I Noted that the air box would be easily accessed by stone, water, etc. form the Engine compartment. So I constructed a every simple Heat shield that extended the side of the air box all the way out to Headlight. And Repeat the test, Reset the CPU and drive for 3 weeks. And to my great delight I got a very noticeable increase in MPG. City mpg now equals 18.8-19.7 mpg And my Highway now is 23.7-24.4 mpg.


So to recap it all:
Old MPG about 14.7 mpg City
New MPG about 19.2 mpg City

Old MPG about 18.1 mpg Highway
New MPG about 23.5 mpg Highway

These mpg are the median of the mpg data gathered over the 3 week tests. The Ranges of each test can be found above. These test where run like this :
1 week City driving
1 week Highway driving
1 week City driving

(This is my driving patteren for work)

HowTo :
1. unseal lib of air box.
2. remove air filter.
3. Remove Stock air box.
4. remove attached elbow on front of air box. (cut off both revitets)
5. create simple heat shield ( to hold it in place use the front most bolt of the air box, make sure that it extends the pasanger side of the air box all the way out to the head light. this is keep the road crap outta the airbox)
6. put back in the air box.
7. put back in the air filter.
8. reseal the lid.
9. reset CPU.


Pictures soon to come

What model/year Isuzu do you have?

I did a somewhat similar modification to my intake. I dremeled out the front of my airbox, then removed the sheathing around the headlight to allow cold air to enter the airbox directly. This in combination with my dynomax muffler gives a better throttle response and more power. This has really worked out better than the calmini cone filter for me. However, I did not notice any increase in MPG. In fact, it might have dropped a bit, but that's probably due to 'more spirited' driving egged on by the new vroom-vroom sound my truck makes.

I plugged up the air inlet hole that you are using as your primary inlet on the side of the airbox since it is facing the engine and is sure to be exposed to hotter air (even with a heatshield).

Wish I could get 18MPG city, with gas prices around 2.30 in my area.

I drive a 01 Rodeo Sport (was a softtop, nows a hardtop).
V6 Manual, with no mods other then a new stero and this one.
(aka everythings stock)

Ps. filled out today (6/1/2004) with 13.221 Gallons and had driven 245.8 miles which come out to 18.591 mpg (City)

I get 18/22 on my stock 2000 Amigo.

I would like to see those... you have me intrigued <img src="/forums/images/graemlins/smile.gif" alt="" />

Cheers <img src="/forums/images/graemlins/cheers.gif" alt="" />,
Santi

You can also get a better exhaust system for more mpg...+4 spark plugs did my trooper good 2!

I must have the luck of the Irish because my 96 Rodeo 3.2 V6 with a manual trans gets 23 mpg on mixed highway and city driving. But, i don't have any mods on it yet <img src="/forums/images/graemlins/smile.gif" alt="" />

I would like to see some pictures as well. I want to see what you have done. I can't seem to picture what exactly you have done.

I have a K&N cone filter, new Cat converter, Glass pack, New plugs and wires, new O2 sensor, new map sensor.. on my 93 3.2L.
My MPG is about 13-14! <img src="/forums/images/graemlins/barf.gif" alt="" /> In other words my Trooper gets Crap for gas milage.

Platinum +4's give good power but are not a good answer for newer isuzu's that monitor the resistance across the spark plug. Bosch has not got the right resistance on these and your PCM will not like it.

The flashing yellow light gets annoying too.