MPG sensor in '85
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Joined: Sep 2009
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MPG sensor in '85
Not a problem as much as an observation. I reset my fuel rate sensor a few months ago. It was reading 18.9 mpg at the time. I've left it on and been watching it very very slowly climb back up from 0.0.
This is my daily driver so I've put plenty of miles on it and it finally hit 15.0 mpg today. Does everyone's do that? Seems ridiculous.
This is my daily driver so I've put plenty of miles on it and it finally hit 15.0 mpg today. Does everyone's do that? Seems ridiculous.
Melting Slicks
Joined: Dec 2009
Posts: 2,232
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I guess it depends on how you drive it. After you reset it, it'll read like the instant mpg reading for awhile, then slow down, usually in under 50 miles.
Has your driving habits changed? What's the coolant temp reading? If its running under 185*, it'll really effects mpg.
Has your driving habits changed? What's the coolant temp reading? If its running under 185*, it'll really effects mpg.
Melting Slicks
Joined: Nov 2007
Posts: 2,830
Likes: 147
From: Gainesville FL
I guess it depends on how you drive it. After you reset it, it'll read like the instant mpg reading for awhile, then slow down, usually in under 50 miles.
Has your driving habits changed? What's the coolant temp reading? If its running under 185*, it'll really effects mpg.
Has your driving habits changed? What's the coolant temp reading? If its running under 185*, it'll really effects mpg.
Melting Slicks
Joined: Dec 2009
Posts: 2,232
Likes: 284
Hotter is better for mpg, you don't want to cook your engine. A good 195* is the best for mpg/performance. I'm doing alittle experiment over at SV, I installed a 205* stat & got over 3.5-4 mpg more then my average over the years, which was around 24mpg. I'm trying a couple other things to get to 30mpg, I don't know if i'll make it though, the 84 is the least fuel effiecent of the c4s. I wouldn't recomend running a 205 stat where its hot, I'm in Wi. so its not super hot like it is in the south.
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Nah, temp has been steady 170s to 210 in this car for years. I just think my sensor is funny to start at 0 and work it's way up literally 1/10 of a mile at a time for months
. Guess I should just be happy all my 25 year old dash lights still work, regardless of what they say I can always flip the switch and ignore it.
. Guess I should just be happy all my 25 year old dash lights still work, regardless of what they say I can always flip the switch and ignore it.
Burning Brakes
Joined: Apr 2004
Posts: 762
Likes: 2
From: Huntington ma
And, in the '85, at least, there is a value in the constants table (in the ECM BIN file) called "Display Fuel Flow Rate". If you like to amaze your friends, you can edit that scalar value and make the MPG readouts show about anything you want.
Look, we're getting 300 MPG!
Harder to make it actually be Accurate. The scalar value says it's in GPH, the value that works for mine, that causes the displayed MPG values to match the Real MPG, is about 4.31. That's with 24# injectors in there, and "stock" fuel pressures.
Look, we're getting 300 MPG!
Harder to make it actually be Accurate. The scalar value says it's in GPH, the value that works for mine, that causes the displayed MPG values to match the Real MPG, is about 4.31. That's with 24# injectors in there, and "stock" fuel pressures.
Race Director
Joined: Apr 2003
Posts: 17,699
Likes: 1,667
From: moraga ca
When you reset your mpg indicator, if the car is at an idle, it'll start at 0. As you drive, it'll calculate your mpg from the reset moment on. If you were idling for a while after the reset, the computer will have some catching up to do to calculate your overall mpg. Try resetting the indicator when you are on a cruise. It'll start out at over 20 mpg and work it's way down when you hit stop and go traffic. You might feel better about your mileage.
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