LB_RX7

So I've been thinking about how the FD3S (MT) gas mileage is and it's not all that great especially how gad prices here are in Southern California, but hey it is a sports car. So I'm wondering if it's possible or a way to modify the car to get it a better gas mileage rating ? I'm not a mechanic or whatever but I know there has to be some sort of possible way to improve this right ?

lOOkatme

iTrader: (19)

Get a tune for mileage (powerFC). You can lean out the cells that are cruise...then richen the cells as you put load to the engine. I do this on mine.

Prôdigy2nd

iTrader: (3)

this....

Under vaccum while cruising im into the 14's afr... no need to burn extra money for no reason... lol

I drove 500 miles on mine to a wedding last year, not boosting at all...
vaccum the whole time, I averaged 26.4 mpg (US gal 3.78l)

my speedo is out about 8-9 kph at 110kph though, but still flipping great mileage for these cars, and modded to...


J.

RotorMotor

iTrader: (5)

Yes:

http://cdn-1.motorsport.com/static/i...15931/s1_1.jpg

djseven

iTrader: (56)

Buy a different car. Mileage is terrible around town in a FD not matter what you do. Interstate you should see 20-24mpg if you stay out if throttle which is great considering the engines age and performance.

Tem120

iTrader: (5)

I run in the higher then 14.7 in cruising you can lean it out more I've not measured my PG's since tunning but I believe its not terrible . for a rotary I get better MPG's then my friends rx8

adam c

iTrader: (2)

I used to get 9 mpg with a stock ecu. This was all "in town" driving. After getting a pfc, the mileage went up to 12 mpg around town. That's a pretty significant increase.

I dont take the FD on trips, so I cant compare hwy mileage.

If you are truly interested in good mileage, getting a tune up for your right foot is the key.

djseven

iTrader: (56)

With a Pettit remapped ecu you can almost see the gas needle dropping sitting at a red light.

00SPEC

iTrader: (9)

if money is the issue, yes, a different car.

power FC, as others have said, is pretty much the only way, which costs ~17-1900 to purchase install and tune..

you can go the used route and save some hundreds, though you (generally) won't know if you got a bad unit until it is too late..

adam c

iTrader: (2)

Yeah, mine was a M2 stage 3 remap. Similar to the Pettit. Awful on gas.

jacobcartmill

iTrader: (6)

oh my gad, not another one of these threads!

LB_RX7

Oh my god not another one these *** holes

lOOkatme

iTrader: (19)

I average 22MPG, but I always romp it. I tuned the cruise cells around 14.7 to 15.3AFR. I ramp it to lower AFR's as load increases.

Remember that carbon build up leads to sticking seals and such. so running the car on the leaner side of cruise could be a good thing. I believe stock tried to stay around 14.7AFR from the stock AFR map I saw.

octanepwr

Just be glad you don't live here:
I pay your equivalent of $7.60 USD/gal, and I get ~11mpg town ~14mpg highway hard to tell exactly as I premix and never fill up entire tank (also add the Castrol TTS full synth two stroke cost to this @150:1)
I do have a single turbo conversion 363rwhp but yeah, you guys have it bloody easy haha.

lOOkatme

iTrader: (19)

I get 22MPG, 24MPG if babied, and I have 340-400WHP depending on elevation. Need a better tune perhaps?

wstrohm

Our near-stock '94 gets around 13 mpg in city, 22-23 on the road at ~80 mph. It seems to gulp fuel most while warming up; I wonder if the coolant sensor is calibrated for extremely rich A/F when cold. If so, adding a resistor (maybe around 620 ohms) across the sensor input to the PCME might reduce fuel usage when cold... but have never tried this.

Sgtblue

iTrader: (16)

*A new set of plugs and wires.
*New O2 sensor (or)
*a PFC with a tune as described.
*Check pressure in your tires. Keep them stock size.
*Downpipe, hi-flow cat and freer flowing cat-back than stock.
*Less restrictive intake than stock.
*Use only premium fuel.
Not likely to result in dramatic improvement, and almost all of these things cost money. And since it sounds like you're not a DIY'er, it's going to be enough money that you could buy a lot of gas for the FD...or a beater econo-box for the daily commute.

jkstill

iTrader: (11)

Leave your FD in the garage and admire it.

octanepwr

The highway mpg was a 400km trip mostly babied. It has been tuned by the best rotary mechanics in the country - they have made a 6 rotor engine and many 4 rotors and it has a link G4 ecu. So I am not sure another tune would help.
Check out these vids (engines by them)

It does have a large extend port and 2200cc sec injectors. Has good plugs/big exhaust/air filter/good tyre pressure/premium gas etc) but I am yet to do the fuel filter which might help a little but I would be surprised if a lot as not appearing to cause starvation issues.
I think they are just thirsty

ksu-chewie

iTrader: (14)

I've been playing a lot with my idle AFR and cruise AFR on my PFC. My drive to work (25mi) is mostly highway with a few side street stops. Averaging 26 mpg.

wstrohm

Good to know that one owner is smarter than Mazda!

We are not so lucky!

SA3R

Yes, I believe below a water temp threshold (possibly below 60C, that number stands out in my memory) the ECU runs richer, and this forms part of its cold start 'choke' operation.

By adding the resistor, as they do on other cars, you're essentially fooling it into thinking the engine is warmer than it is in reality, so it will lean the fuel out.

The problem comes along when that resistor is still hard wired in there, and the engine has finished warming up. The coolant temp sensor will still report an artificially high coolant temp, and the ECU may do odd things as a response (IE lean it out further still at normal running temp) and this could be bad.

If the OP is worried about fuel economy, maybe he should:

-remove excess weight or go on a diet
-choose low rolling resistance tires on stock rims
-remove the AC system, gut the interior, throw the spare out
-service the driveline. Change to thinner weight oils, new plugs, check compression, etc
-turn the boost down
-free flowing intake
-less restrictive exhaust
-Trade it in for a sweet deal on a Prius?

I can understand wanting to fix a rich AFR running problem, sure. But if this is just about the car drinking fuel because its a turbocharged rotary, and the OP is not okay with what is considered normal fuel usage, maybe a change of vehicle is in order?
A turbo rotary (espcially of 1990's era design) is not going to be as fuel efficient as a Camry or a new Civic. Thats just not going to happen in the long run, unless you turn the car into something it was never supposed to be.