slowrx

Guys,
Im getting bad fuel mileage.
About 13 to the gallon if Im doing my math right.
Is there something wrong?
Car has power, idles good, runs good.
It has a mazdaspeed intake and a racing beat exhaust.
What should I be looking at?
Like the rx8, hate the mpgs

I8U

iTrader: (1)

First thing you should do is look at the bottom of this page a click on one of the many other threads that talk about MPG's. If no answers there, use the search button.

invasion08

iTrader: (7)

Need more info on the car. How many miles, last time the spark plugs and coils were changed.

slowrx

Car is reaching 80k miles.
Sparkplugs were done about 5k miles ago.
Coils... not done didnt even know they were a service item.
My right foot doesnt help either that racing beat exhaust sounds sooooo good!
Car runs like a top in my opinion... doesnt seem like there is anything wrong at all.
What else can I look at?
Or where should I start looking?

Razz1

Then its your right foot!

Clean the MAF

04RX8man

Coils, MAF cleaning, Seafoam.....

Jedi54

iTrader: (7)

if the car runs fine, then it's most likely your driving.
Wouldn't hurt to do a little maintenance on it though. I would look into coils / wires, clean the MAF, clean your air filter, run some fuel injector cleaner in your next tank of gas, and stay away from the 9000 redline.

04RX8man

^but going to 9k is all the fun of this ride....but then again im always up around there abotu 10 times a day (well at least 7k) and i get 17 or so but i'm happy with that!

shaunv74

Idling and city mileage kill the gas mileage on this car. It does well on the highway but terrible in city driving. My advice: take the back roads to work.

deadphoenix52

also, dont be retarded. be sure to divide by the number of gallons you put in the tank, not the size of the tank. you'd be surprised how many people do this.

04RX8man

^yeah I know alot of ppl that do not do it right!...haha

slowrx

Not retarded I know how thats done.
I've done it before when tracking mileage on my Oldsmobile and my SE-R.
WOW just wow at how long the coils last on these cars... 20k miles its a joke IMO.
You know the problem with this car is the fact it build rpms really quickly then its hard to keep it under 3500rpms.
Shifting at 3k rpms... forgot to mention my stage II clutch isnt helping either.
Ill clean the MAF today and report back on my fuel usage soon as those 8 gallons are gone.
Maybe check the coils too since im already at it.
Thanks for all the replies

04RX8man

^20k is a litte low on the life...(some here do follow the 20k or so change) I'm on my originals at 49k miles and going to change them just as a maintenance thing....no misfire or anything and does not feel to have a loss of power but when u drive it everyday it's hard to see that!

wmb_8

i took a trip to fl this past weekend, i got 21mpg setting cruise control at 85mph, my 8 is a 04 completely stock with 40,000 miles....not too bad imo..now compare it to the wifes 3...hmmm

slowrx

Far as I know mine haven't been changed or maybe they have since i bought the car used.
Idle quality, power delivery still seem good to me. Where can I buy them from? Id like to skip the stealership if I do need them.
IMO if I were to get low 20s ill be happy considering the type of car this is
Of course that all goes out the window when the rpms get out of hand
Ill be cleaning the MAF tomorrow, checking the air filter, and the coils.
Ill need an oil change soon.
Should I stick with mazda's recommendation of 5w-20?
Sorry if i have too many questions, im a rotary virgin

slowrx

Ok,
So my last tank got about 15mpg, but that included a lot of around town stop and go driving. The one before that got me 18mpg and included some freeway driving. My guess is the only time i will see 20s is just straight highway driving. Most shifting was done around 3k rpms with a few winds to 7k in between.
Now the great news is my check engine light came on for no reason
Ill do my oil change today, clean the maf *finally* and check my coils....
Ill keep you posted on what I find....

Proxi

Definitely check or maybe even replace your coils with a new set (especially since you're reaching 80k miles on your car). I recently replaced my plugs, coils, and even plug wires a couple of months ago - and I definitely saw an increase on my MPG. My car is at about 53k miles and I was getting around 17mpg on my drives from home to work and back. Been driving the same route and my manner of driving lets say is close to a spirited drive. But after replacing my coils, plugs and wires - I'm now getting around 19 to 20 mpg.

dondo

iTrader: (7)

coils make a huge difference. i changed mine out at 60k.

04RX8man

was your CEL flashing? did you get gas recently before the CEL?

oh and your oil issue!.....use NO LIGHTER THAN 5W30!

shaunv74

I have not seen revving make that much of a difference in gas mileage. Shifting at 3K is just silly. It's too low and the car will have to work harder at that RPM since you're way out of the torque band. My advice is cruise between 3-4K rpm and stay out of the stop and go.

OEM Coils can be bought online at rosenthal mazda or www.finishlineperformance.com. They are about $30 each and you need 4. My advice on coils is to replace them with BHR's ignition coil upgrade kit. It's ~$480 but includes coils good for 800hp, plugs, wires, and a wiring harness. You'll never have to worry about them again. The OEM coils you'll have to keep replacing every 40K miles or so. PM Charles R. Hill and he can set you up if you're interested.

A little about the OEM coils: they're definitely the weak link in the engine. Keep in mind the rotary is much more demanding on ignition coils than a piston engine. There are 2 coils in each housing and each of those coils fires in every combustion stroke so the coils are doing the work of three coils in a regular piston motor. I'm not suprised they only last 1/3 the life of coils in a piston car.

slowrx

CEL was not flashing.
It came off one day after i parked it for about 30 mins then came back and started it, CEL light came on solid and has been ever since.
I did my oil change and cleaned the MAF, used 5w-30.
Ill take the car to the shop tomorrow and check what that light is on for.
The coils will get replaced but not at the moment. I know the plugs were done earlier this year so they should be fine. Ignition wires might also be replaced when coils get done.
Local mazda dealer mechanic told me the sideports start to open at 3500 so if I stayed below that i would see better mileage.... supposedly. I still let it run its full rpms range at least once a week though
For now it will be parked until I feel like throwing more money at it.
I appreciate everyone's input. Thanks!

Cam

iTrader: (1)

If youre getting 15mpg's in city/stop n go driving thats the norm.

I get 15 in city driving.

Right now I do about 90/10 highway/city and got 24.2 last tank, and 25 the tank before.

53K miles. stock. coils changed at 45K.

Its the nature of the beast. just enjoy the car.

shaunv74

check your gas cap. Twist it on until it clicks a couple of times. It's common for an unsealed gas cap to cause a CEL. It's part of the emissions system.

04RX8man

^agreed since it came on right when u started it good chance it's the gas cap make sure it's on tight...i alwasy click mine about 6 or 8 times to be safe...then go to autozone or advanced auto to get the code read for free..if it's a gas cap it will say "evap leak very small" or some type of evap leak...

slowrx

Thanks everyone for the replies.
The CEL light was a small evap leak so I guess everything is fine
Mileage well, lets just say its been doing really great sitting in the garage and all