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Bad MPG

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Old Mar 11, 2006 | 10:31 PM
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Bad MPG

My 90 150 302 2wd is consuming fuel. I've not owned the truck but a few months and haven't driven it alot. The tranny is also about shot. Will a rebuild on the tranny help MPG?
 
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Old Mar 11, 2006 | 11:15 PM
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is it carbed or EFI? Auto or 5 speed? When's the last time it got a full tune up? Could be cats, or O2 sensors also. I would look into cheaper options before jumping into the expensive stuff.
 
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Old Mar 12, 2006 | 10:15 AM
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Being a 90, it would be EFI. A full tuneup, making sure your sensors are all working and not having a slipping tranny will all help your mileage, but at the end of the day, you're still driving what amounts to a large brick. Also, I don't know exactly why it is, but something about the EFI systems on these trucks just makes them use more fuel than they should. I can get better mileage with a well-tuned carb than most of these trucks do with EFI. Anyway, from my experience and what I've read on here, basically any EFI V8 Ford truck will get about 13 mpg, give or take 1 or 2.
 
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Old Mar 12, 2006 | 12:09 PM
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What do you consider bad gas mileage? If you have only owned it for a few months, maybe it is in perfect tune, but your expectations of what a 4500 lb. truck can acheive.
 
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Old Mar 14, 2006 | 09:56 AM
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Thanks all
The truck has a new Jasper crate motor. It is EFI and Automatic tranny. I've installed new sensors [egr, map, tps, & IAC etc.]. It has headers and dual exhaust but the O2 sensor has not been installed. I'm going to drill a hole in the header and weld on the bung.
 
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Old Mar 14, 2006 | 09:59 AM
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Ben
Have you ever converted an EFI to carb?
 
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Old Mar 14, 2006 | 11:07 AM
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Originally Posted by vnmous
Thanks all
The truck has a new Jasper crate motor. It is EFI and Automatic tranny. I've installed new sensors [egr, map, tps, & IAC etc.]. It has headers and dual exhaust but the O2 sensor has not been installed. I'm going to drill a hole in the header and weld on the bung.
This is your problem-no O2 sensor---the poor EFI cant get feed back and cant fine tune itself.The EFI is in open loop and is running rich. Put the O2 sensor back and you should at least have the same MPG as before. The O2 sensor is VERY important to performance and to MPG.

Dont you have a "check engine" light on in the instrument panel??

Place the O2 bung at the same distance from the heads as on the stock vehicle and preferably--on an crossover pipe --so that both banks gets measured.
 

Last edited by phoneman91; Mar 14, 2006 at 11:17 AM.
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Old Mar 14, 2006 | 11:10 AM
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does that dual exhaust have a cross over pipe at all. if not have one put in and thats were you should install the o2 sensor.
 
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Old Mar 15, 2006 | 03:23 PM
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I would put an o2 sensor in it should be throwing codes also the headers dont help ur mpg any especially if you like to hear um!
 
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Old Mar 15, 2006 | 07:24 PM
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the slipping tranny doesnt help any but is not the main problem, new engine will suck more gas until fully broken in, hook scanner up-check inputs & outputs (engine coolant temperature E.C.T.) if pcm thinks engine is cold it will feed more fuel the o2 sensor is also an input that wouldnt hurt to have either (you need it) the temp sending unit for the guage on your dash is different than the ECT sensor DONT BUY AFTERMARKET
 
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Old Mar 15, 2006 | 08:25 PM
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My 1990 Lariat XLT with a 5.8 engine gets about 15 MPG not loaded and on the freeway. Around town with a load it's about 10. It is tuned to perfection.
 
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