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Unread 05-06-2009, 09:42 PM   #1
BRayf78
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ZJ 318 Throttle Body vs. MPG

I have a 95ZJ with a 318 V8. I currently get 15mpg and I was wondering if changing the throttle body or adding a throttle body spacer would increase my MPGs?
Thanks

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Unread 05-06-2009, 09:48 PM   #2
bcollier1823
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Some people say yes, some say no. I bought a holley 52mm throttle body for my 5.9l and saw zero mpg increase, of course that's not what I bought it for so no biggy.

People claim things like the 'tornado', etc. work... but I haven't heard results from reliable results that would yield it worth while to purchase.

But maybe somebody else has had better results than me.

As far as your mpg you might try a basic tune up, intake, and if you live in a cool place removing the a/c compressor. All three of these have produced solid mpg increases for me.
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Unread 05-06-2009, 09:51 PM   #3
WhiteOut
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Is the Jeep stock? Before adding stuff, do a tune up. I get around 15-16MPG highway, which is good.
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Unread 05-06-2009, 09:52 PM   #4
tirus89
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Adding a throttle body spacer does nothing unless your jeep is carbureted, and its not. Save your 60$ and put gas in your tank. Changing the throttle body wont do anything, but a good cleaning of it will add some punch to the jeep and some MPG.
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Unread 05-06-2009, 09:54 PM   #5
BlingBlingZJ
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you should be happy to be getting 15 mpg's shhh I get an average of 11 on mine
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Unread 05-06-2009, 11:03 PM   #6
Toliver09
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or you could replace the 5.2 with a 4.0 and get 21mpg highway (4" lift and 31's, 3.73 gears)
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Unread 05-07-2009, 08:06 AM   #7
BRayf78
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Yes it is a stock 5.2.
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Unread 05-07-2009, 08:33 AM   #8
WhiteOut
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Tune up then, you might be able to get 1 or 2 more MPG out of it. A sure was is to place an ad on Cgraislist, sell the Jeep and buy a Prius
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Unread 05-07-2009, 10:11 AM   #9
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Quote:
Originally Posted by Toliver09 View Post
or you could replace the 5.2 with a 4.0 and get 21mpg highway (4" lift and 31's, 3.73 gears)
or you could get a 4.0 with 31's, BB, and 3.55 gears and get 25mpg highway like me
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Unread 05-07-2009, 10:55 AM   #10
SpeedyCat3
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Quote:
Originally Posted by Toliver09 View Post
or you could replace the 5.2 with a 4.0 and get 21mpg highway (4" lift and 31's, 3.73 gears)
Quote:
Originally Posted by ZJcrawler45 View Post
or you could get a 4.0 with 31's, BB, and 3.55 gears and get 25mpg highway like me
Good thing you guys are always driving down hill.
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Unread 05-07-2009, 01:04 PM   #11
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like mentioned above...tb spacers aren't much for stock...and the bored tb won't do much for improvement as well. A combination of add ons will see and increase but not by themselves. I myself will get crappy city mileage but on hwy will see 20 plus wind aided and abot 14-16 against. So be happy with the 15-16 and get the "real" tune up.
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Unread 05-07-2009, 02:28 PM   #12
Toliver09
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get a slightly more mild cam. along with exhaust and intake upgrades a slightly larger cam will yield higher highway mpg's
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Unread 05-07-2009, 02:56 PM   #13
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Almost all your driving is done with the engine computer in closed loop mode. With computer controlled engines using crank position sensor input to control the ignition timing, cam position sensor for injector synchronization, O2 sensors to monitor the A/F ratio, and etc., there is almost nothing you can do with exhaust mods, air intake mods and the like to increase mpgs when driving in closed loop mode. Some mods can increase hp somewhat when the computer goes to open loop mode, but that only happens with the throttle wide open when the engine get to higher than usual rpms.

Forget about larger throttle bodies and TB spacers as far as mph is concerned.
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Unread 05-07-2009, 03:20 PM   #14
nashmd454
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Quote:
Originally Posted by rm2001wj View Post
Almost all your driving is done with the engine computer in closed loop mode. With computer controlled engines using crank position sensor input to control the ignition timing, cam position sensor for injector synchronization, O2 sensors to monitor the A/F ratio, and etc., there is almost nothing you can do with exhaust mods, air intake mods and the like to increase mpgs when driving in closed loop mode. Some mods can increase hp somewhat when the computer goes to open loop mode, but that only happens with the throttle wide open when the engine get to higher than usual rpms.

Forget about larger throttle bodies and TB spacers as far as mph is concerned.
very well said and explained...I have learned the hard way....
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Unread 05-07-2009, 03:21 PM   #15
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good quote Toliver...but not all 2% are illinois.
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