I'm getting 20mpg with all my mods on 50/50 driving. As for leaning out the 8 that's a really bad idea the rotary burns hot enough leaning it can only lead to really bad things.

 

Leaning out your engine will lead to engine failure, dump idea ! Don't think the electronics will let you do that anyway.

 

I averaged 19.x mpg over 8,330 miles around the country, including plenty of city traffic sections and driving from LA to Oregon up the Pacific Coast Highway which is anything but straight and level, including spending a few hours driving around San Fransisco, over to Crater Lake, etc...

The highest tank I've ever gotten was ~27mpg, though that was deliberately hypermilling the car on the highway, and it was incredibly boring. I normally averaged 21-22 highway without a problem. Mixed was only down to 18-19. I only got as low as 16 if something failed (like ignition, cat, etc...) or the entire tank was around town.

Yes, all RX-8's have a wideband in the upstream position.

Read this thread entirely before doing that though, because the ECU knows what it should be running at, even if you program it to be different, it will correct anyway: https://www.rx8club.com/series-i-eng...timing-216087/

Specifically the section of the thread which shows how the ECU wouldn't let him run lean for very long before correcting fuel trims to bring him back to stichometric, ignoring his preprogrammed lean AFR target.

 

I might be doing something wrong. On average im only getting about 40 miles per quater in town and from what im reading that not normal. Any suggestions? I cruz between 4000-4500 most the time unless im burning carbsbut still getting that kind of milage. Could it be the refurbished engine.

 

Lots of variables here can contribute to your mileage. Condition and health of your engine, coils, wires and plugs come to mind first, Secondly how do you drive, lots of hard acceleration and/or stop and go city driving is another factor. Warming up the engine all the time in a cold climate is another factor. Condition of your tires, their air pressure and any extra weight you might be regularly carrying in the trunk are other factors. Even a dirty intake filter can rob you of mileage. A dirty MAF or bad ECU can also contribute.

We would need much more info to help diagnose your poor mileage.

 

Mod edit:
Completely off topic, this thread is about gas mileage, go here to a new thread and ask your question: https://www.rx8club.com/forumdisplay.php?f=197
-RIWWP

 

Well if it helps any the engine only has about 15,000 on it and how do i check the coils im familiar with plugs air filters and most the basic stuff as ive worked on cars a good chunk of my life but am new to the rotary scene. How would i go about checking the ecu? Also im running gtx 5-30 if that makes a differance.

 

Oil weight and brand and type have no real impact on mileage until you start passing 35+mpg, you might pick up a point for 0w20 in that case, but it won't show up for an RX-8. Not much oil passing around and you need a +/- 5% change to see it show up, which is significant.


Coils can be tested with a coil tester, looks like a spark plug with a clamp, available from most auto parts store for $5 or so. "ECU" isn't something to worry about, you would have far more problems if your ECU was faulty.

 

Ive alose read somewhere on the forums here about premixing. Some details on that would be great. or if u could direct me towards the thread for it. Sorry for all the questions

 

It has it's own section in the new owner's thread, and is offtopic in this one.

 

I live in a city, so drive in traffic all day long.. I guess my awful MPG is cause im no USA driver on highways.. is this to high? shall I get ecu flashed ?

 

I travel to work and back home 24.8miles a day. I fill up my tank and get around 167.7miles on a tank, but thats in heavy traffic on my way to work and fairly heavy traffic on my way back home. This is a combination of light driving and fairly hard driving depending on whether i need to jump traffic to get to work on time.

Current gas prices in South Africa is like 16.89miles/gallon (US).

So sunday night i fill up and Friday morning i fill up again. Sometimes Thursday evening i fill up again.

 

i must be doing something wrong i only get 180 miles to a tank in town only

 

Just checking in, no time to read 39 pages, but....

The things that helped me were: clean stuff up (MAF, ESS, grounds), good coils, good plugs, air filter. The $100 thread below has that stuff.

Then, if at speed, drop the front an inch with a spring like an H-tech. that rake is good for 1 mpg (5%)

Is console hot? that can indicate a clogged cat. that will hurt mileage as well.

Tire pressures. Also, dragging brakes. Are your wheels always dirty? I had to change caliper seals to solve that problem.

Access Port and Tune, after the other stuff done.

I have a medium speed commute, average speed is about 55, with no lights for the first 25 miles. Then a dozen lights the next 15 miles. I average about 23 PG. If I get stuck with city driving, I drop to the very high teens.

that help?

 

I've been getting 16-17 mpg but thats during rush hour traffic in -20 C weather so fairly long warm up times.
Before it got cold and I wasn't driving in heavy traffic I was getting around 20 mpg.

 

Get about 17.5 avg

 

The way I drive I'm getting around 16mpg...guess I'm not that conservative. zoom zoom

 

Sorry can anybody tell me how much stock the gear **** weighs?

Thanks!

 

The first tank of gas after buying my 8 got 18mi./gal, since then, I've averages 16-17.5 with mostly highway driving... May be time to check into my MAF...

 

I was only getting ~15mpg in my old slush box 8. Of course to get it to go I always had a little heavier right foot.

 

I've only checked three tanks so far, but it's been 16 to 18 mpg. All the driving was in the city, though my schedule allows me to avoid rush hour at least. I suspect that the recent throttle remapping will raise it a bit.

 

I typical get 17-19 in my 09 R3.

 

Best I got was 18

 

matthunter1448 what model, year ,and how much mileage on your RX8 ?

 

I was excited to get 260 miles out of a tank of gas on my 09 R3 this week. Best mpg yet! I do 50 mi hwy to and from work so 100 miles a day, blah! Came out to 18.5 mpg! Oh yah and it's got 46k mi on the odo all stock! Usually average 15-17 the way I drive though.