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Old 03-19-2009, 03:21 PM   #15 (permalink)
EcoModding Lurker
Join Date: Mar 2009
Location: Vancouver, WA
Posts: 48

Active Learning - '93 Chevy Suburban Silverado
90 day: 10.67 mpg (US)
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Originally Posted by EcoJeeper View Post
.... I drive one.

I drive a 1994 Jeep Wrangler. It is the 4 cylinder 5 speed manual model with a soft top. I would like to get a hard top for it eventually both for looks and for a potential lessening of drag (I would just assume with the various little air gaps between the soft top and half doors that it would be worse for gas mileage than would a hard top with full doors). Anyway, it's got around 138,000 miles on it and still runs pretty good.

Now I have a bit more hope for improving it (when I first bought the Jeep I was only getting around 13 mpg).
Well I dont feel so out of place then with my '93 suburban. while Im not trying to be an hypermiler thats not to say some of their techniques wont come in handy.
Looks to me like you need to start where I'm starting and find out why your mileage is so bad to begin with. This rig will be used to advertise our Preschool business and to pick up after school kids. Still I like to be as green as financially possible.
First thing was to figure out why 10 mpg. It also had a bad hesitation just off idle on acceleration and general mediocre performance. You'd think sucking that much gas that it would perform like a race car.
First mod was to get a laptop interfaced with the ECM so I could see what the engine is doing with what sensor data.
Second mod was to get a mileage computer on it so I can see the instant mpg.

I found out quick, thanks to the laptop, that my hesitation always came when the egr was coming on.. BUT the EGR circuit is working fine. Apparently this Year GM engines don't modulate the egr. It is either on or off. I haven't been able to find anything that says different. So now Im suspicious the CAT is plugged.
Anyway without a few pages of details im up to about 13mpg. but I will get better if I have to go electric on the front axle.. 12 miles round trip to the school I should be able to do that with a few batteries. Expensive motors and controllers though.
Id say check your O2 sensor, check your EGR valve, and check your cat for airflow resistance. my mothers jeep gets 20-22 on the freeway so I am pretty sure you should be getting better then that.
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