Hey i was thinking about getting the new megasquirt ms3x and was wondering if i could add a hotwire maf with the map sensor etc. to increase mpg. S4 na (maybe future turbo)

 

you need to do a lot of homework.

Adding a maf will not give you mpg. It is simply a sensor the ecu uses to help determine engine load and airflow.

That being said, I'm on MS2. I get 18 city, and 23 highway ( I think that's pretty much n/a window sticker). Turbo car though. You can do it.

 

I'd have to agree. Doesn't seem like RX7 was meant for good gas mileage. My car seems very off and on. There's no in between or partial throttle. Even when the pedal is partial the throttle is off or on. And it seems like the tranny causes just enough resistance to slow down the car rather than idle comfortably. I think MPG is just something you give up for not owning a Honda. I'm not mad about it. LoL

 

I got 18-20 city and 22-25 highway MPG in my NA , my Turbo is probably 16-18 city 18-22+ if I had to guess

Rotary > Pistons

 

That's not too shabby. I'd take that. I haven't calculated mine yet so I cant say for certain but doesn't seem too good lol

 

i get 14.99mpg in the city on my fc with a medium streetported n/a and a rb true dual.

 

I average 19mpg's. turbo, small street port. I'd say 70/30 city/highway.

 

15 city, 19 highway. Turbo, streetport, stock ecu. I think the culprit's a worn out O2 sensor. I'm leaning towards buying another FB because I can't stand getting 330km to a tank not even being able to enjoy the car.

 

15 city, 21 highway exit to exit. Large street port stock ECU.

 

what are you guys tuning tables?
MMoore was it tuned by a pro or did you do it yourself? ANd how much hp are you at?

I was starting to study how to tune and realized i should be able to do better than a 20somthing year old processor.
I was thinkig of using a host of new sensors and whatnot to increase mpgs considerably

 

why would you think a MAF would net better fuel economy? it will require more tuning and net the same results as a MAP based system with less tolerance of intake system leaks. it is a step up from an AFM but MAP based systems will compensate for variations in intake system pressure/vacuum automatically.

say you blow off a few vacuum lines with a MAP based system, the only thing you will notice is lower boost due to the leaks.

 

Tuned it myself. Lots of patience and reading. There are quite a few good efi books you can even pick up at Books-A-Million or whatever your local retailer is.

312Rwhp is what I was dyno'd at last April.

The hindrance isn't in the processor, it is that the tune was for the oem, Mazda had to compromise their tune for long term (read warranty length) reliability, power, and mileage.

 

MAP Sensor VS. Maf Sensor | Tuning MAP sensors | Evo Maf

This is why i brought it up. But if you guy say its not necessary then ill omit it.

 

well the rx8 has a maf sensor and still gets about the same terrible mileage as all of the rx7s lol


doesn't really seem worth the trouble.

 

the additional fine tuning aspect of the MAF sensor won't really net you much mpg in a rotary, a good tuner will get the same results from a MAP based system. the differences come in altitude changes where the MAF will compensate much more accurately where the MAP sensor will do rough corrections based on ambient pressure changes.

the intake system on these engines is also antiquated and tends to develop leaks which can be present only cold versus warm or simple get worse over time under any condition, such as the poor injector sealing techniques used in the 80's(the injectors fit sloppily into the engine and push up under boost).

 

it gets bad mileage because its a heavy car with short gears, and not because of the AFM...

i think if we have a preference for the MAP sensor, its because we're used to it....

 

People shouldn't forget that Mazda was able to achieve impressive highway mileage in the "lean burn" 12A in the 70s. EPA ratings were between 30 and 35MPG. They lost that ability when they had to run richer to keep the catalysts happy.

That said, city mileage is always going to be rather disappointing just due to combustion shape.

An AFM is less important on an ECU able to run in observer mode, tightly controlling AFRs using a wideband O2 sensor. MS3 can easily do this as well as advanced model based enrichments which make an enormous difference over what the stock ECU is capable of.

 

Ivebeen able to get 23mpg on a stock s5 na... and on my street ported t2 with a pfc.
City mpg are probably single digits, I measure SMILES per gallon driving a 7 with the top down and boost up in the city!

 

This... My old large streetport na s5 made about 7mpg city.... If you're looking for mpg in a rotary, then you picked the wrong car....lol