what is your MPG

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Set your cruise control at 60mph, drive by mile marker on the highway, start your stop watch, drive by next mile marker on the highway. Note your time.

The percentage off from 1 minute will be your increased speed. ie if he watch shows 52 seconds you calculate your speed, 60/52 * 60 = 69.2mph.
 
Use roadside mile markers, as referenced above.

Highway, preferentially flat. Stop at a mile marker, set trip odo to zero, drive, stop at tenth marker, note trip odo. Repeat three times, then average trip odo readings. Trip odo average / 10 miles = correction factor
 
I don't see any mile markers where I live. Freeway exit signs are all messed up here. In one direction it shows a number of miles, in the opposite direction a different number.

I tried to confirm the speed with my wife's car until I realized hers is probably off too just like any other car on the road.

Mine is really funny, the speedo is progressive, however the ECU knows the exact speed. I can read the ECU speed off the OBD2 with an app on my phone and confirm it with the GPS.
On the LC I don't think I can do the same thing.
 
I got a phone app with a GPS speed feature among others.
It turns out the speed difference is not that big. I run 285/75-16.
At 35 mph on the speedo, the gps shows 37-38, at 65 mph gps @ 68, 70 speedo - 73.8 gps, 75 speedo - 78-79 gps.

Not really bad.
I need to also compare the distance travelled between the LC and a different one.
 
Best I've ever seen on my '94 was 14mpg.

It got 12.5mpg between St. George and Orem UT towing a ton of steel.

For the last 2 years it passes emissions by a wide margin. Pays to replace the vacuum lines and assure that the sensor connectors are in good shape and clean. and that you have no broken sensors.
 
For my 97 LX I've calculated and validated that the speedo is 10% off with 315/75/16. Not sure how some people got 12%, is t factory tires 265/70/16?
 
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512/75 16's?? Damn those are over 20" wide and 46" tall! Lol

Pretty sure stock was 275/70 16.

Each brand will be a little different as well inflation, load, wear, etc. My tires were 11% when brand new. 315/75 16 Duratracs but could be 10% now. :shrug: lol

Qball said:
For my 97 LX I've calculated and validated that the speedo is 10% off with 512/75/16. Not sure how some people got 12%, is t factory tires 265/70/16?
Click to expand...
 
My speedo is 7 mph off. At all speeds. If my speedo says 10 I'm going 17. If my speedo says 55 I'm going 62. I have a buddy that is a cop and he radared me and tested while driving next to me. I used to have a Garmin that would show speed via GPS but I have no idea where that is because it was antiquated.

I'm not concerned by the Miles racking up on my rig. I've owned it since new and never will sell it. I guess it impacts how I figure MPG and oil changes but that's not that big of a deal. Maybe someday I'll get around to fixing it. I'll add it to the "Book of Things to Do" for my 80.
 
odo can't be off 7 miles-that would add them every time you start it. -if the speedo needle was installed wrong it would say 7 when at 0. ODO is what needs to be checked for miles.
 
Correct. Speedo is off 7 miles per hour. I have no idea whether or not the odometer is off or not. Not too concerned about it...
 
Very to o an easy approximation of error-interstates have the mile markers. Can quick calculate in your head for oil changes etc. . I check my fuel mileage just mostly as a general indicator of my engine health-if it changes with no other signs somethings wrong... like checking your cholesterol or blood pressure lol.
 
scottryana said:
512/75 16's?? Damn those are over 20" wide and 46" tall! Lol

Pretty sure stock was 275/70 16.

Each brand will be a little different as well inflation, load, wear, etc. My tires were 11% when brand new. 315/75 16 Duratracs but could be 10% now. :shrug: lol
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Doh! Talk about fat fingering that one. LOL!

I adjusted my scangauge with 10% and it is spot on according to GPS, mine is falken wild peak AT(very impressive tires BTW). According to tire calculators there is 11% difference but as we all know tires wi same size varies in size depending on manufacture and style.
 
I change my oil at 2500 miles. Always have. If that means it might be 2700 or so, so be it. Gotta run, got a tune up and EGR delete waiting for me. :)
 
Filled up my tank today (only was half empty) because I replaced my plugs, wires, distributor cap, and PCV valve and wanted to see if I got any improvement. Got 10 mpg. This is a huge improvement after replacing the O2 sensors. Before replacing the O2 sensors I was getting about 6 mpg. Hoping to get to 11-12 before I do the EGR delete and advance my timing. If I get to 15 mpg I will pee myself.
 
I'm in orbit when I see double digits......:lol:


If I see 10 around town my math is jacked.......:)
 
LS1FJ40 said:
Filled up my tank today (only was half empty) because I replaced my plugs, wires, distributor cap, and PCV valve and wanted to see if I got any improvement. Got 10 mpg. This is a huge improvement after replacing the O2 sensors. Before replacing the O2 sensors I was getting about 6 mpg. Hoping to get to 11-12 before I do the EGR delete and advance my timing. If I get to 15 mpg I will pee myself.
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If you want to get best MPG possible then leave the EGR system alone, it's there to help you save gas.
 
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