RX8Club.com - What is an M and L Flash?

An Article i wrote for the May issue of Rxtuner.

J-K-L-M do you know your re-flashes?
Mark Gaal “PoLaK”

Where is the Power?

Rx-8 owners across the country have gawked at the low dyno numbers the Rx-8 is producing. The 8 supposedly makes 238hp at the crank which should translate to about 190-200whp taking into account drivetrain and frictional losses. Actual mustang and dynojet numbers are much less, ranging from 168-180whp (wheel hp). So, where did the power go? Well popular belief is Mazda screwed up, back in May/June of last year when pre-order buyers were expecting their cars, there was a long hold up at port. The cause behind it EPA2 emissions regulations, Mazda had forgotten that the Rx-8 would have to meet newer and more rigid requirements for the 2004 model year, specifically a Catalytic Converter that would have to last 170k miles. So to satisfy the already anxious and complaining pre-order buyers Mazda flashes all the cars waiting at port with a J. It’s signified by a “JX” port campaign sticker under the hoods of the first shipment of Rx-8’s to the US.

Problems with J

J is pretty much Mazda’s half-ass attempt to meet EPA2 and get buyers their already deleyed cars. The entire J flash is rich meaning, to preserve Cat-life, Mazda used a fuel map that tuned the Air to Fuel Ratio (AFR) pig-rich across the powerband. What this effectively does is pack more fuel in to the combustion chambers then there is air to combust it. This un-burnt fuel then keeps the exhaust temps down, thereby preserving Cat-life. Everything is spiffy for the first few weeks, until a couple of the more enthusiast oriented owners go out and dyno their then 247hp cars. They find the low dyno numbers, post it on sites like Rx8club.com where it is debated. Soon after Mazda issues a revised Horsepower number 238 (which is still a bit optimistic). They offer owners or pre-buyers that bought before this announcement a $500 debit card and free maintenance for the life of the warranty or a buyback of the car at purchase price. Not a bad deal for 9hp, but the reason behind it isn’t a “calculation” error.

K

K came along after Mazda had a few months to research into what would be the best performance/mileage VS Cat-life flash for the RX-8. K from an engineering standpoint was light-years ahead of J. Mazda leaned out the AFR though some of the powerband, although Mazda was still playing it safe from around 6800rpm to redline where the flash became rich. Again, this had to be done due to the natural high-heat out-put of rotarys. However to Mazda’s surprise they began receiving reports of Cats failing, not because of high-heat, instead the un-burnt fuel from running so rich, began accumulating in the cat effectively corroding it. So the engineers at Mazda come up with an idea that is, well a first in the sub $100,000 car market, a little jewel called “L”

L

The L Flash was a major recode of the ECU. Obviously Mazda has been putting some serious hours into R&D. Most of the complaints have been centered upon less than smooth around town driving, and poor gas mileage. Fixing these issues is harder than it seems, numerous factors have to be considered. The Air/Fuel mixture has to be lean enough to get good mileage, but rich enough to prevent pinging. It also has to be smooth for general driveability, and still produce the expected power. Juggling all of these issues can be very challenging. Mazda’s answer is essentially to pack two maps into one ecu. The L Flash gives one map for gears 1 through 3, and one for gears 4 through 6. Reasoning being, that load, and potential for pinging, are higher in gears 4 through 6 because loads on the engine are higher as speeds increase. So with the previous flashes, the tuning may be right for highway driving, but very rich for the lower gears. So the big difference with “L” is it tunes based on what gear you’re in! Active tuning is accomplished by voltage readings provided by the MAF sensor as well as another variable sensor. It leans or richens the fuel mixture at different points based on gear. For example in 3rd gear the AFR is pretty lean up until about 4,600rpm where it becomes very rich, very fast. Now in 4th gear the AFR is pretty lean until 2,900rpm then it becomes much to rich. Although “L” is a major improvement, these dyno results show that there is still room for improvement. Hats off to Mazda for releasing a product that delivers significant improvements.

M

The M Flash is a further evolution of L, trying to improve more on mid-range smoothness, gas mileage, and cold start flooding problems. It seems as though Mazda released the RX-8 with maps that they knew were too rich, and incrementally are re-flashing the car until they find the sweet spot. This isn’t too bad of an idea for reliability, unfortunately there are side-effects, or else there would be no need for all these flashes. “M” further leans out the mixture in the low and mid-range rpm areas for all gears. This will give a bit more power, smoothness, and mileage at those points. Another change in the M flash is that when cranking a cold engine now, the first 3 seconds there is no fuel injected. This was done to combat the complaints of flooding in cold engines. Early reports of those on www.rx8club.com who have received the M flash substantiate these claims. Almost all have reported noticeable results, especially in the feeling of more mid-range punch and better mileage. It’s to early however to know if the flooding problems are resolved, but you can’t argue that Mazda is trying. It’s a very exciting change from how things were done in the past, where if you wanted a better driving car, you only option was to wait for the next model year. Now all it takes is the ingenuity of some Mazda engineers, and 30 minutes at your dealer.