Reman Gas Mileage
 

So I just checked the milage on my first tank of gas with the "new" (remanufactured) engine. Of course I have been shifting at 4,000 rpm but this was about 60/40 city to highway.

285 miles on 13.31 gallons = 21.41 mpg

My previous engine averaged around 20 mpg and ran perfect. It developed an idle problem and after the latest flash, would not idle at all. This was at 68,000 miles and while it was at the dealer waiting for a new engine, I got the letter from Mazda extending the warrenty to 100,000. This one idles great. It is very difficult staying below 4,000 rpm after 67,000 miles worth of at least one redline a day!

i got my car re-flashed a few days ago... my idle went from 1k down to about 500rpm. (And it doesn't idle as smooth down there).

i asked jeff to set my idle on the accessport to 950 rpm. He doesn't like setting it that high, but the car runs like a friggin' champ and nothing can trip it up and get it to falter like it could before when it idled 100 rpm lower (such as the ac cycling)

I would kill to have 285 miles.

My gas light always comes on right at 200, I put in about 14 gallons everytime.

The most I have ever gotten to a tank is 215.

I've gone through 2 tanks on my latest reman. First tank was about 50/50 and I got 18. 2nd tank was mostly highway and I got 20. This is with the ac going the whole time and I'm not keeping it under 4k.

Original engine, 1st replacement, now 2nd replacement, I get the same mpg. The only thing that really brings my mpg down is cold weather and short trips.

make sure to drive those engines HARD!

the best way to break in an engine is driving the absolute PISS OUT OF IT. better compression and more horsepower. get the oil changed often, 500, 1000, after 3k oil change you can drive normally.

This might work for piston engines, but is bad advice for a rotary. I broke my denali's ls6 rebuilt engine swap in this way and it runs great, but I have built hundreds of rotaries and would not recommend breaking them in this way. There is no crosshatch to worry about wearing away in 20 miles in a rotary.

Also, the reason you guys see better MPG with your remans is because there is more compression being generated, and thus the engine is more efficient due to less blowby. IT is typical on the older rotaries that are flat worn out to see a 10-15% increase in gas mileage when an engine is rebuilt and compression goes up. They also idle better, start faster, and have slightly better low rpm pullout. It's all a result of the compression being closer to "right". Compression declines over a period of time as the internals wear but you do not realize it.

^

So does this mean I should have my compression checked since no matter what I do I can not get much over 200 miles to the tank no matter how I drive it?

If you used to be able to get more when the car was newer, then yes.

For instance, in hilly east TN, it is hard to get good mpg because of the terrain in many spots. There is almost no flat ground here, and while I dont live in the mountains, the rolling hills take 2-4mpg away from everything.

So someone that lives here is never going to get the same mpg as someone that lives in texas, for instance.

But, if you owned a car since new and used to get 21, and now get 17, then yes the engne is likely moderately worn and compression has fallen somewhat. By the time the car gets to where it won't idle steadily or dies at stop lights, the problem is more advanced...my 117k mile engine has 90psi (below the mazda limit for rx8s of 96) but does not stall or have a fluctuating idle yet. Cars that I have checked that have severe idle issues are in the 80's or below.

^

I got it used and its always been where it has been as far as mpg.

Almost all of my driving is city, I dont know if 200 miles for the gas light to come on is good or not.

As far as compression the car feels pretty quick and I give G35s a good run for there money, even pulling some buy 1.5 cars from a 60 punch.

Eh, you can't go by the gas light, you have to go by the gallons pumped versus the miles obtained.

My gas light comes on and the gauge looks like it is at 1/8. However the car will only hold like 12-13 gallons max if I put gas in it then. This means the gas light comes on too early, and there are still several gallons left in the tank. I have gone 40-50 more miles with the gas light on and still had plenty of gas in the tank.