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Old 09-13-2008, 11:52 PM   #1 (permalink)
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'93 Geo Metro EOC question

I have a question about my '93 metro's throttle body fuel injection system. My main concern is that I heard that instantly restarting an engine (stop light) with a carburetor will use more fuel than letting it idle for a few seconds and that direct fuel injected engines are the only ones that benefit from shutting off for a few seconds (disregarding starter wear). I'm 99% positive that I have a throttle body injection (aka TBI or CFI for fords) and I'm wondering since that was a transition from carburetors to fuel injection if it behaved more like a carburetor with regards to the restarting.

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Old 09-18-2008, 09:37 PM   #2 (permalink)
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You have a TBI. A carb will only waste fuel if you "pump" the fuel with the engine off. TBI has a metered fuel system and it does not use more fuel to restart compared to idling. I do not use EOC myself, but have recently (this week) been trying it. I cannot say if I am seeing an increase in MPG yet since it's so soon.
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Old 09-18-2008, 10:19 PM   #3 (permalink)
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That's funny you say that Johnny, Cause the next two or three fuel checks I do I'm trying it without EOC....LOL
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Old 09-18-2008, 11:30 PM   #4 (permalink)
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Johnny, RacerX you crazy guys. My switch got ya thinking, huh?!

Newton I EOC as much as I can in my 91 I drive probably 90% in town. So I try to coast to every light, to my parking spots, Slight hills. Tbi will use slightly more fuel when starting but not much when warmed up. Much like a carb but computer pumps it for you. I gained 3-4mpg when doing this technique, probably more.
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Old 09-19-2008, 01:19 AM   #5 (permalink)
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Quote:
Originally Posted by bbjsw10 View Post
Johnny, RacerX you crazy guys. My switch got ya thinking, huh?!

Newton I EOC as much as I can in my 91 I drive probably 90% in town. So I try to coast to every light, to my parking spots, Slight hills. Tbi will use slightly more fuel when starting but not much when warmed up. Much like a carb but computer pumps it for you. I gained 3-4mpg when doing this technique, probably more.
bbjsw10, I have a momentary start/stop, EOC switch to the left of my steering wheel. At the MEET Johnny said he doesn't EOC so I thought I'd try it. I'm curious to see if my drop in mpg is the same as your gain.
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Old 09-19-2008, 02:30 AM   #6 (permalink)
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thank you all for the help. i've posted the last few top offs (not as accurate as full tank but for my purposes accurate enough. i also use the same pump as much as possible when i top off) i got up to 55mpg from 47-49 by eoc. tonight i drove about 170miles trying some pulse and glide and when i topped off i got 51mpg i'm pretty sure it was because i was forced to use a different pump and i could hear that it did fill up further into the neck than the pump i usually use. oh well, i'm sure some friend will need me to be their DD again sometime soon lol thank you all again for your help, i'm really glad i found this forum. peoples jaws drop when i tell them i get around 50mpg lol like its some amazingly impossible thing to do
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Old 09-19-2008, 07:31 AM   #7 (permalink)
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Quote:
Originally Posted by RacerX View Post
bbjsw10, I have a momentary start/stop, EOC switch to the left of my steering wheel. At the MEET Johnny said he doesn't EOC so I thought I'd try it. I'm curious to see if my drop in mpg is the same as your gain.
Yeah, forgot about your switch I like where you put it. I bump mine on accident sometimes when reaching for radio. Make sure to post your results up.
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Old 09-19-2008, 07:54 AM   #8 (permalink)
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Unlike most I found worse results with EOC. It may have been too many hills on my commute, or heck, maybe I was doing it wrong. I have decided that for the short term I will not be using it.

I have hemmed myself into a corner by selling off my Buick. We now only have my Metro and my wife's Buick. In short I cannot afford to take gambles with the health of the Metro, and I worry about the effects of bump starts on little Metro axles and CV joints, and excessive starter wear.

That being said there are a couple of stretches that I cut the motor off and coast. One is .5 miles downhill into a stop sign, and one is coming into my little town where there is a .4 miles slight downhill with dropping speed limits.
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Old 09-19-2008, 09:48 AM   #9 (permalink)
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Quote:
Originally Posted by bbjsw10 View Post
Yeah, forgot about your switch I like where you put it. I bump mine on accident sometimes when reaching for radio. Make sure to post your results up.


I HATE when that happens BTW, congrats on your mpg that you got on the way home and I'll let you know on this thread my results
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Old 09-19-2008, 03:11 PM   #10 (permalink)
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Well, You can take this with a grain of salt because I didn't do it over a period of time but I did my daily fuel check and I went down to 60.5 mpg with my altenater turned off so......I don't think I'm going to continue this test. My results turned out to be 5 to 6 mpg lower than what I would normally get for this same trip. To be honest I didn't think it would make that much of a difference. And with your results bbjsw10 it looks like we're in the same ball park....So that's enough testing for me to be convinced... NEXT STOP.....Throttle cable or Cruise control of some sort....

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