seikx8

Maybe the attached AF ratio logged by eManage with Innovative WBO2 would explain the answer.

Comparing the original flash arriving from the Port vs. M Flash at WOT in 3rd gear.

You'll be suprise what a >25% throttle would do to the AF ratio below vs. above 4k.

My best mileage was 19MPG with the M flash, and my worst with the original is 13MPG. But on the average I got 17.5MPG with spirit driving (3k-4k cruising)

Mr M

Just to clear up something, the SSV and Secondary injector operating rpm can vary depending on engine load. They will operate sometime above 3,250 rpm, but exactly when is dependent on driving conditions. Only the VFAD and VDI open at a specific rpm.

mdmaclean

I think that if you used your eManage to collect AF ratio on a few test runs you could answer what is more economical. If you take AF and multiply it by RPM you get a measure of how much gas was used. These could be compared if they were taken in different gears at the same speed on the same road with cruise on.

That would use AF measurements at something other than WOT. Who knows, we might learn something unexpected.

hootersam

After reading all these posts, I guess I should be happy I'm getting 21-23 mpg.

robertdot

I just moved to REAL stop and go traffic, and I'm getting about 100 miles from full to 1/4 of a tank. I wish I was still getting 16-20 MPG.

Xyntax

Thanks for all the useful inputs guys. After seeing that attachment, I got curious on installing an A/F ratio gauge just for kicks. Has anyone done this? If so, how? what? where? DIY?

I'll try to figure this out if nobody can point a direction :D

ezrider55

I do not know if this will help mpg or not, but it is sure more fun to drive in the 3250-3750 rpm range. I feel like true acceleration is just a blip of the gas pedal away. :D

MTLbroker

40 psi? Not to mention uneven treadwear. The cars weighs in at 3000lbs.
Nevertheless, I'm always between 4000-7000rpm. No wonder mpg is suffering. But I did I not read somewhere that if the rotary is designed to be revved to acheive better operating efficiency, higher rpms should not be detrimental to mpg.

takahashi

What 3000lbs going to do with 40psi? Uneven treadwear is not due to the tyre pressure. In fact 40psi just make it flat but not bulge out.

Do you know your tyre pressure will go up to 44psi when you travel 100km/h on a highway for an hour??

Defensive driving course tells me (no change of story for the last ten years) 36psi is recommanded even for small cars, 38 for family sedan. Porsche recommands 42-44psi!! 40psi is ok mate. Start to learn! :D

Please don't start to argue running the car in high rev save fuel too

Xyntax

^ yup. I actually lowered my tires to 36 psi now and it's just the right amount for me. Still has the 40 psi handling but without the rough feeling.

I drive mostly in the city, so I guess my tire pressure won't be going 44 psi often.

Back on topic: I checked out MazdaManiac's excel data on the stock and tuned RX-8's performance he got from his E-manage. I downloaded it from the Yahoo Groups E-manage group. I highlighted the lambda values to colors signifying lean, 50/50, rich conditions. I noticed that his stock made lean to 50/50 mixtures at 2600 rpm to 3000 rpms. Anything after that gets richer and richer. As for his tuned setting, the mixture went lean to 50/50 around 3000 - 3750 rpms. Also, his tuning made the graph smoother and the rich mixture closer to 13.5 instead of the 12.0 - 11.0 that it was making on stock setting.

I know that RX-8s aren't made equal. Some of us here get higher performance than others (stock). Some get higher MPG than others. I hope my CZ unit will be here any day so I could take my own logs and compare it with Maniac's. Maybe my 8 runs the same as Maniac's stock or maybe mine takes leaner mixtures at 3250 - 3750 range. I have a multimeter ready to be used to take statistical data out of my car. Now, I only need to figure out which wire to tap it on, which one does the o2 sensor send signal to?

r0tor

iTrader: (1)

i think people are getting WOT fuel maps confused with partial throttle fuel maps. In partial throttle or closed loop mode the a/f ratio is pretty much always 14.68:1 (this is what i've noticed anyway with my CANScan).

i haven't had much time to log fuel milage but i did notice I was getting 30mpg doing 30mph in 5th gear <shrug>

Xyntax

Oh I am fully aware of the fact that Maniac's data was a WOT. I don't have my own tools and logs yet. And since his is the only excel data I could find on an RX-8, I'll take whatever I could find there.

My Canscan will be here next week :D

Mr_Intarnet

I'm getting my blue MT next week and can't wait.

This discussion reminds me of my Honda Prelude VTEC days. That baby hated sitting around at 3000rpm, but would sit happier, accelerate better and just generally drove better if it was kept at about 4000rpm all the time. I'll be doing the same with the RX-8 (after running the engine in, ofc )

When my ex used to drive the Honda when I was away, I told her, 'if you want to drive this thing properly, pretend it's your Nissan and thrash it'

I always checked the mileage when I got back, it drank petrol like crazy, maybe as much as 15-20% extra, I assume because she used to drive around at 2000rpm.

MTLbroker

Just tried 40 psi in the car for a couple of days. Seems too rough over the bumps. Roads are bad up here. Maybe it's subjective. Going back to 32 psi.

MTLbroker

Also, pyschologically, couldn't get my brain around overinflating the tires. If my cold tire psi is 40, does that mean that after extended highway driving, the tires'll be at 50psi? That would exceed maximum load, no? I ahd visions of the tires blowing up like balloons. Oh well, live and learn.

O.R.A.

Race tires rarely gain 10 psi through a race, so I doubt that a street tire driven on the street will gain that much. Maybe 4 psi.

310Guy

I can't believe you guys drive with 40 psi.

Doesn't the car bounce around? I mean, it's like driving on four ballons.

I was at 36 psi to see if mileage improved. It didn't but the ride quality was worse - very bouncy. I'm back to 32 psi and my still crappy mileage (13 city).

Xyntax

Whoa, I thought my message was about the RPM range and not the psi in your tires to run on. I have been driving with 36 psi since I last posted in this thread. 40 psi was fun but it was a little too rough whenever I run pass the railroad (which I pass everyday).

rx8spiritR

rx8 is totally not a reliably car afterall, not even in stock form..............
i always worry about unstable idel, those brake noice, 11mpg, engine temp, engine noice, stink exhaust...........it just doesn't make sense that i am actually drive a new car with only 4K mile and everything stock. hey XYNTAX, you mind let me check out your car after you got your CZ unit? i want to do a compare, i don't mind drive down to San Jose.

Brian1f

RX8spirit M flash fixed most all of those things except maybe brake noise.