Gas mileage after flash and brake stomp test
 

Guys itdoesnt look like the flash has affected my mileage at all asit seems to remain the same as it always was in 100% city driving. But I neverdid the brake stomp oil sweep test after getting the flash b/c I wasnt interested in resetting NVRAM. Did all of you really do the test afteryou got the flash? Are there any of you that got theflash neverdid the test and now have better mileage? Or did allof you who claimto have better mileage after the flash perform the oil sweep test?

i have the M flash and got to test the mileage this weekend. on my first road trip with the car last year the low fuel light would come on at about 285-290 miles and i was verry happy to make it to 300 miles. however on this first post M flash road trip the light did not even come on until 300 on the way up and 311 on the way back. results- on the way out i got 22.5 mpg heading up into the mountains of washington state at @80mph and 4k the whole way. on the way back coming down out of the mountains doing @80 mph and 4k rpm i got 23.5 for an average of 23 mpg. i have no doubt that at 65 i would have been over the epa 24mpg figure. conclusion- more power and better gas mileage. go get youselves an M flash!!

After resetting the PCM and having the L flash, I got the best gas milage I have ever gotten, 23 MPG on the highway. Usually average about 19. I was super excited. Also noticed that resetting the PCM makes the car very fast for a short period of time, especially with the Stage 1 unit hooked up. I loved it.

I also noted statistically higher MPG after the M flash. For many tankfuls, I couldn't get over 17 MPG, but my last two have been right around 20. No change in general driving style or routes.

YMMV (literally).:D

I have "L" Level. On the trip home from Rotary Revolution yesterday I averaged 23 mpg cruising at 70-75 MPH with a 10-15 mph head wind. Best milage ever.

This MPG thing will be tough to nail down with all the driving styles on the forum.

i cant get better than 17 !!! my dealer says he flashed my car. I have yet to see the paper work.

Thre break pump thing does not work for me either.

it doesnt work for me either.... how old is your car? mines is newer and probably already had the "L" flash, so i'm wondering if maybe it doesn;t work on newer models?

I dontthink you guys understood what I was asking here. I wanted to knowif there were any of you who DID NOT dothe brake stomp test to checkfor the flash but still got better mileage after installing the flash.

I supposedly got the M Flash. But the brake test doesnt work. ,
Brake test. 1. Turn ignition just past ACC to ON but dont start the car. 2. With key in this postion tap brakes 20 times in 8 seconds.

Does this supposed to work with the M Flash?? If it does my dealer is a crook., I also looked for some kind a sticker on the car and found nothing.

Here's my experiment. Before M flash, highest I could get was 16mpg (average of 14.5) and that's already pushing the granny shifting everyday in every situation. After M flash, I did the brake test before I left the dealership lot. Drove granny style the whole time. I did not measure my mpg that time coz I already had half tank left when I had it flashed. The next tank I did 17mpg. And then I filled up again to do the "normal" driving which is 4K shift points. Before I drove out of Chevron, I did the brake test again to make my car learn a different type of driving. Turned it off and then on again...drove off fast. :D

To my surprise, the 9k revving on highway, 4k-5k shifting on city and 3.5k cruising gave me 18mpg!

I will try granny driving again on the next tank, but this time I won't be resetting anything.

Oh yeah, I have the least smoot on my exhaust tips ever since. That's gotta be a good thing ;)

i understood jerky. i did not do the brake test and got the mileage i posted previously.

Same here jerky, I never did the brake test but I have the paper work and sticker to confirm my "M" flash and when conditions are right I noticed a few MPG increase. I drive 100% city and I'm talking about numerous stoplights that are 1/4 mile apart and shifting at 4000-6000 rpm frequently, I average 15 MPG. That's not too much less than my former 03 EXV6 accord. Driving conditions play a big part in mpg, unfortunately I'm in the worst kind, but "hey" at least I'm having alot of fun, something I couldn't say about the Accord!

From what I can tell the only portion of the NVRAM the brake tap test will reset is the eccentric shaft data.

The long and short fuel trim data will remain intact.

My theory is, since the 8 is unlike any other car, conventional wisdoms don't seem to apply. With a conventional car, "granny-driving" will get you better mileage than "spirited-driving". With this car, it seems to do the opposite. My idea on this is the computer is monitoring velocity of exhaust gases moving through the CAT; if it senses low velocity (ala granny-driving) then it adds fuel to cool the converter. If it senses higher velocity as would happen with running up the revs, then it backs off on fuel richness because the velocity moving through the converter is enough to keep it cool.

The Renesis runs hotter than conventional engines as I'm sure everyone has discovered by now. In order to meet EPA requirements for CAT life of 120,000 miles, Mazda must have chosen to use fuel to cool it and extend its life. Which works, but it also cost the engine some power which we all know the story on too. Canzoomer's Stage 1 mod puts things back to original programming so you get power curve back, but at cost of CAT life; most likely it will die around 60K which was the old requirement before the new laws took effect. Probably what Mazda originally designed for which would explain the h.p. specs they published before they had to fiddle with the ECU to come up with a way to meet the new EPA requirements.

My suggestion? Don't granny-drive; drive it like it should be driven....use the rev's and try this for a full tank or two. As some are reporting, this is getting them better mileage than before when they were supposedly driving for gas mileage.

I love this car; it's a great machine in so many ways, and a truly unique driving experience. :)

Ole Spiff Itried what you suggested and I had the worst tank ever. I barely made 220 miles onthat tank and thats only b/c I didnt fill up until the gas nozzle was well below thelast notch on the guage. I wasnt redlining all the time butI was keeping the RPMs between 3000 and 6000 for most of the driving onthat tank. This wasin an automatic too.

Looks like Im justgoing to have to do the brake stomp likeeveryone else w/the flash did. So far every tank Ive had after getting the flash has beenworse than before I hadthe flash.

My gas mileage went from about 16 to around 23 after the flash, with mixed driving.

My mileage went from 18 to 21 (mostly freeway driving) after the reflash

This is too funny.

I'll take ANY improvement...

Last tankfull = 13.26 mpg.

I'm to have the M calibration this Wednesday (5/18). I hope it improves my fuel mileage... :(

What kind of gas and octane are you using? I use Shell regular, 87 octane. I have an MT so I'm not sure what difference an automatic would make, but there's got to be something off with your car to be getting such poor mileage.

Make sure your tire pressures are correct; 32psi cold. Make sure your air filter is clean. Make sure you're using 5w20 oil; not something thicker like 10w40. Try disabling the DSC system (if you have it) in case that's dragging and causing rolling resistance. I'm trying to think of anything that might help your mileage. I drive mine "briskly" shall we say, and I get around 19mpg with a 50/50 mix of street/highway driving.

What kind of mileage do other AT owners get? Maybe it's the AT that doesn't do as well compared to the MT.

ole spiff,
I agree. Drive the car as it is designed to be driven. Of course now some common sense does apply! Granny driving doesnt work with this engine. Hell, it's a 2 cycle motor, You'll "gum it up"! I wish all the electronics an smog stuff could just be yanked off! Oh well those where the days!
olddragger

I'm surprised nobody has 'corrected' your theory yet!
What cooling effect are you expecting from 900 to 950°C exhaust gases (typical of WOT / high revs conditions) flowing through the catalyst? Exhaust gas temps are proportional to engine speed (higher gas flow) and engine load (more combustion energy). You must had up to 50°C to get the catalyst mid-brick temperature due the essentially exothermal reactions going on there.

Having done a search on the following topics these last few days :
- reduction of peak power from 250 to 238 hp
- low fuel economy of some cars
- successive re-cals
here is my theory : the Catalyst Temperature Protection strategy imight be the central point of all these issues. This PCM strategy module actually had more fuel under certain conditions when it estimates the engine operational conditions might lead to catalyst overheating (beyond somethink like 1000 - 1050 °C). This estimation is made by looking at all sorts of parameters like temperatures (air charge and coolant/cylinder head), AFR, spark advance, ...

Now the theory :
1) Initially, the engine was estimated to deliver something close to 250 hp. But in order to lenghten the catalyst service life as per US (and probably EU) regulations, the engineers might have calibrated the Catalyst Temp Protection strategy in order to give more fuel to reduce combustion temperature (only when needed), therefore running richer than the optimal LBT fuelling and loosing power.
2) They might have overdone it a bit and most cars running in area with mild / warm weather have suffered major cat protection overfuelling and hence, low FE.
3) The Mazda engineers (pushed by customer complains)decided to revisit the calibration of this strategy module in order to find the best compromise between FE and cat protection (less overfuelling than before and/or overfuelling only at hotter engine operational conditions).

If this theory is true (which implies it can be false) :
- Car running in hot areas (SoCal, Fl, Az, NM, Tx...) have a poorer FE than cold areas. They run richer at high revs / high loads.
- Cars that had a decent FE before re-falsh did not see any improvement.
- Cars that run in cold area have decent FE (compared to hot areas). They still run supposedly at LBT fuelling.
- Cars running in hot areas will keep their crap FE because the cat temp protection is still overfuelling.
- Cars in the mild areas might have seen a nice change in their FE thanks to the reflash.
- Cars that are running in borderline conditions (rather hot) could see an improvement with high octane fuel : less knock -> more spark advance thanks to knock control -> more heat in engine, less in exhausts -> cat protection off.
I might had other corollaries when they come to my mind.

Also my guess is that the EU 231hp power figure is closer to the truth as EU regulations autorise EU inspection and test of engines at the factory. They must come withing 5% (if I remember correctly) of homologated peak power, peak torque, peak power speed and peak torque speed. Engine manufacturer tend to be honest with the advertised power figures in order to avoid problems later. The 238 vs 231 difference would therefore be a question of US advertised power vs ISO / SAE test standards (see thread : https://www.rx8club.com/showthread.p...threadid=26394 )

IKN

I have since day one used 91 octane. I've been keeping a log for almost 2,500 miles. My average for this is 14.53 mpg. I've tried everything from DSC off, to letting the car shift itself, to me doing all the shifting.

My last reading (13.26 mpg) was the result of brisk driving with me shifting.

POS Santa Monica Mazda service manager (Jack Rollens = doesn't know a thing about the RX-8) said the car is well within mpg range. I don't know what 8 he looked at but it could not have been mine.

I'm trying Galpin Mazda this week for the M calibration and discuss my poor fuel mileage.

I agree that something must be wrong with my 8, especially reading how other owners, whether manual or auto, are getting such better mileage than I do. It doesn't make sense.

I've had my K&N intake sitting in my home for almost two months. I'm waiting to see what can be done before I install it. The last thing I want is for a dealership to say, "well, you've got an aftermarket intake installed, that's your problem..."

To iKnow....

My "theory" was that since Mazda engineers had apparently used fuel to extend CAT life as per the many discussions I had read on this forum, there had to be some kind of relation to fuel usage and how you drive. Many have reported after a day of racing, or autocrossing, their cars actually have better mileage than before. The ECU is apparently "learning" from your driving style and adjusting itself accordingly. Since those who were driving theirs the hardest were getting increases in mileage afterwards, my guess was granny-driving would do the opposite.

My "theory" was just an attempt to guess as to why this would occur. Your explanation is better detailed and makes sense...thanks for the input!