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True, but the figures I read out were the low and high averages while cruising. I suppose it'd equate to a highway average. :)

Once I go through the "proper" estimation procedures by filling up at the pump I'll update my MPG readings. But for now, the scangauge makes me happy.
 

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How much will old catalysts (over 100K miles) affect gas mileage?
 

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How much will old catalysts (over 100K miles) affect gas mileage?
That's hard to determine. If the vehicle ran well (for instance - I have a Dodge Caravan with 230,000 miles that I put a new bigger exhaust on it today and the cat was fine, so we reused it), it could last several hundred thousand miles. If the car burned oil badly, it may not last 100,000 :zdunno:

Since I have a 1995 'Bird and it burned oil pretty badly when I first got it, I replaced my cats. Since I put the Motor Honey to it for a few months, it kind of stopped burning oil (that stuff worked better than I EVER expected). I still have to add oil, but very infrequently now for several months. Before the Motor Honey treatment(s) (as in SEVERAL bottles), I used to have to add a quart every couple weeks.
 

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mpg

Engine: 4.6l
City MPG: 17
Highway MPG: 26
Fuel Used:
Average highway speed: 72-75
Average Climate: 30's winter,90s summer
Mechanical Mods: quiet a few
Milage on the engine: 120k recently motor went down
Comments: replacing engine soon
 

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Speaking of MPG, I gotta take some new readings since I've eliminated my EGR circuits (Daniela kept complaining the car was 'surging' and I knew that was the EGR system screwing up, so I disconnected it).
Expect worse gas mileage with the EGR gone. These cars get better mileage with a working EGR system - especially if you get a code for "excessive EGR flow".

Al
 

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I have only put 2 tanks of gas in her but here it goes....

Engine:4.6 2v
City/Highway combine MPG:18.6
Fuel Used:87
Average highway speed:65
Average Climate:50 degrees-ish
Mechanical Mods:none
Mileage on the engine:115,600
Comments:needs tune-up
 

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That's hard to determine. If the vehicle ran well (for instance - I have a Dodge Caravan with 230,000 miles that I put a new bigger exhaust on it today and the cat was fine, so we reused it), it could last several hundred thousand miles. If the car burned oil badly, it may not last 100,000 :zdunno:

Since I have a 1995 'Bird and it burned oil pretty badly when I first got it, I replaced my cats. Since I put the Motor Honey to it for a few months, it kind of stopped burning oil (that stuff worked better than I EVER expected). I still have to add oil, but very infrequently now for several months. Before the Motor Honey treatment(s) (as in SEVERAL bottles), I used to have to add a quart every couple weeks.
What he said. 94/5's that huff blue smoke tend to wipe them out around 100k. I usually run a bit of ATF in mine a few miles prior to an oil change to help swell the seals and clean out deposits, seems to preserve at least a quart of oil between changes.
 

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What he said. 94/5's that huff blue smoke tend to wipe them out around 100k. I usually run a bit of ATF in mine a few miles prior to an oil change to help swell the seals and clean out deposits, seems to preserve at least a quart of oil between changes.
Wow, I aught to start doing this then because I am going through a quart of oil every 700-800 miles. My gas mileage has taken a hit since last year, I'm lucky if I get 24 on the highway. That's when I'm actually trying. Plugs (Autolite AR764) have about 15,000 miles on them. Wires are about 7 years old though. I regularly do the Seafoam treatment every 10,000 miles and I run 89 grade E10 gasoline. No CEL's, no driveability issues. New tires, transmission fluid of course. Air filter is cleaned every 10,000 miles. PCV valve isn't stuck. All the vacuum tubes have been replaced in the engine bay.
 

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1995 Cougar
Engine: 4.6 SOHC
City MPG: 11
Highway MPG: 24-25
Fuel Used: 93 octane
Average highway speed: 80-90
Average Climate: 70s
Mechanical Mods: a few.
Milage on the engine: 166k
Comments: OD likes to kick on and off so I usually just turn it off when I'm not on the highway. And the 3500 tq converter makes a pain in the arse to launch in city.
 

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Engine: 4.6 PI
City MPG: 15
Highway MPG:18
Fuel Used: 93 octane
Average highway speed: 105mph
Average Climate: Michigan so different every day
Milage on the engine: around 50k, not even 100 miles on heads and cams
Comments:Brand new heads cam intake true dual CAI
 

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Car: 95LX
Engine: 4.6 SOHC
Mileage:100k+ (odometer broke at 97600) :)
City: 19-20
Highway: 25+
Comments: Stock drivetrain, needs valve seals - just did a long trip with over 800 lbs. of ppl, pet, and luggage - 22 down with some traffic and high winds. 28 back with no traffic and cruise set at 75 for just about the entire trip :D
Mods: Spectre CAI (constructed by me), Magnaflow DIDO 2.25 duals, with hollowed out cats.
 

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True, but the figures I read out were the low and high averages while cruising. I suppose it'd equate to a highway average. :)

Once I go through the "proper" estimation procedures by filling up at the pump I'll update my MPG readings. But for now, the scangauge makes me happy.
I agree.

On my '95 Tbird, '07 FX4, and the '01 Mercury GM ..... after using the SGII since Feb 2010 ..... I find that the Average MPG displayed from fill up to fill up if no stops with shut downs are between (like on a trip) ..... the SGII Average MPG is within a tenth or two of the calculated MPG from the last stop. My speedos are dead on, time is a constant, and this tells me the PCM gives a good read on GPH rate for the SGII to be so close.

Now, it goes without saying, if you stop after 76 miles and eat a meal and then restart you spoil the SGIIs ability to accurately reflect AV MPG for that tank to tank run.

I use the instant MPG above the Av MPG readout to hone my right foot's ability to make bigger MPG numbers. Really makes good habits, much like the old days and my Daddy did with his "Mile-O-Meter" which was a vacume gage with a coded scale.

Something else I play with sometimes is I start the car, get out of the drive way and out to the main road, get up to speed, and then unplug and replug the SGII up and that way I see what she'll do on strictly highway runs without the mileage killing low speed driveway and kill and back road. Just for kicks.
Of course, this returns higher numbers than total use, but it gives a good idea of strictly "highway averages".

:)
 

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I agree.

On my '95 Tbird, '07 FX4, and the '01 Mercury GM ..... after using the SGII since Feb 2010 ..... I find that the Average MPG displayed from fill up to fill up if no stops with shut downs are between (like on a trip) ..... the SGII Av MPG is within a tenth or two of the calculated MPG from the last stop. My speedos are dead on, time is a constant, and this tells me the PCM gives a good read on GPH rate for the SGII to be so close.

Now, it goes without saying, if you stop after 76 miles and eat a meal and then restart you spoil the SGIIs ability to accurately reflect AV MPG for that tank to tank run.

I use the instant MPG above the Av MPG readout to hone my right foot's ability to make bigger MPG numbers. Really makes good habits, much like the old days and my Daddy did with his "Mile-O-Meter" which was a vacume gage with a coded scale.

Something else I play with sometimes is I start the car, get out of the drive way and out to the main road, get up to speed, and then unplug and replug the SGII up and that way I see what she'll do on strictly highway runs without the mileage killing low speed driveway and kill and back road. Just for kicks.
Of course, this returns higher numbers than total use, but it gives a good idea of strictly "highway averages".

:)
Well, my odometer doesn't work, I don't have a scangauge, so I do it the old-fashioned way, I log the mileage with the GPS, then fill the tank again and divide mileage by gallons used. Therefore, my MPG is always the average of the entire tank city/highway/country/idling/racing/whatever.

The GPS makes my numbers VERY accurate. I guess on that 2nd tankful listed above, I did more highway driving since the avg is up.
 

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My odo is broken too NetKeym, I do it the same way as you :) No matter what driving your doing, it always gives you the avg of what you have done for that tank, and therefore is the most accurate way of measuring Avg. MPG imo.
 

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I guess I'll throw mine out there

City: 15-18
Highway:23ish
Combined:21
Grade: 87/89 (Depending on where I am)
No upgrades. Best I ever got was 31.5 MPG while driving through Nebraska heading back from Yellowstone it was like 317.2 miles on 10.07 gallons of gas (89 grade). It made me feel good that a v8 4000 pound car could get such good gas mileage. Average speed on that tank was approximately 75-80 MPH.
 

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I guess I'll throw mine out there

City: 15-18
Highway:23ish
Combined:21
Grade: 87/89 (Depending on where I am)
No upgrades. Best I ever got was 31.5 MPG while driving through Nebraska heading back from Yellowstone it was like 317.2 miles on 10.07 gallons of gas (89 grade). It made me feel good that a v8 4000 pound car could get such good gas mileage. Average speed on that tank was approximately 75-80 MPH.
What is it about that state that makes for good gas mileage numbers? :) My best tank was there, coming home (to SD, at the time) from Colorado, and I didn't believe it when I filled up in Valentine and calculated 31-32 MPG.
 

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What is it about that state that makes for good gas mileage numbers? :) My best tank was there, coming home (to SD, at the time) from Colorado, and I didn't believe it when I filled up in Valentine and calculated 31-32 MPG.
Maybe it's downhill both ways!

Like my dad used to tell me he had to walk a mile uphill both ways to school when he was a kid!
 

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Like my dad used to tell me he had to walk a mile uphill both ways to school when he was a kid!
I literally did.

I walked up the hill from the house to the main drag, over to the school, and down the hill to the school.

Up the hill from the school to the main drag, over to the house, and back down hill.

So, yes, uphill both ways. Took driver's ed there when I was 14, so I had to walk in the hot July sun. And natch, in the winter (one of the winters we had this white stuff all over the place - and no, I don't mean cocaine!)

RwP
 

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I literally did.

I walked up the hill from the house to the main drag, over to the school, and down the hill to the school.

Up the hill from the school to the main drag, over to the house, and back down hill.

So, yes, uphill both ways. Took driver's ed there when I was 14, so I had to walk in the hot July sun. And natch, in the winter (one of the winters we had this white stuff all over the place - and no, I don't mean cocaine!)

RwP
Yeh, I took Driver's Ed when I was 14, had my license when I was 15 in Maine. I don't think they do that anymore; I think you have to be 16 to get a license.
 
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