Silver_Excalibur

iTrader: (1)

Hello everyone I believe that I have a issue with my car. My gas mileage is terrible. Just completely awful and yes I know these cars aren't great on gas but what I'm getting is not every pickup truck mileage. A full tank of 92 octane Shell V Power gas will only last me about 150ish miles. I do have different driving styles though. If I'm beating the hell out of it I get about 130, 150ish is relaxed but some spirited driving included, and 180 if I just baby the thing and cruise at 3500rpm all day. The plugs, wires, and coils are new, maf is cleaned, no check engine lights, and I did the 20 stomp reset. When I first got the car I was getting 230-250 to a tank and still having fun driving the car. Things started going downhill once I started doing basic maintenance like changing all the fluids. I don't believe that anythings wrong since theres no CELs or leaks.

Also car in question is a 6 speed GT 2007 Mazda Rx-8 with 54k miles and solid compression as of august.

Mods done to the Car are: Lighter wheels, went from all season tires to summer, on powertrix coilovers, and sohn adapter. I've read somewhere that summer tires have a high road resistance which affects gas mileage.

I searched around and I saw a thread close to mine and someone mentioned a clogged cat. I looked up the behavior of a car with a bad cat and my car does not act anything close to it.

Sorry if that was a lot to read but I just want to be through so I can avoid the first " have you done this or that" replies. Thank you for reading.

Chrishoky

iTrader: (9)

im sorry to say but this mileage isnt that far off from the norm. I typically get 175 miles in spirited driving, and about 200-215 if I really baby the car. Im not sure you have that much to be concerned about...

Silver_Excalibur

iTrader: (1)

Well its assuring that there isn't a problem. Looks like its time to buy a daily.

gwilliams6

Time to check over these maintenance points, several could affect your mileage. Your mileage does seems a little low to me. I have 58000 on mine and am doing better on mileage, spirited and non spirited driving. BTW I have a BHR ignition system and a Mazdaspeed CAI which both give a slight performance/mileage bump.

30,000 miles:
- Replace Ignition coils
- Replace Plug wires
- Replace Spark plugs
- Clean MAF (mass air flow sensor)
- Clean ESS (e-shaft sensor)
- Reset ESS profile
- Clean power steering connections
- Clean battery terminals and clamps
- Replace transmission fluid
- Replace coolant (Mazda FL-22 is highly recommended)
- Replace air filter
- Replace brake fluid (fluid in the brake lines AND the clutch line)
~$300 USD in parts if you shop smartly.


every 60,000:
...all 30,000, plus...
- Clean all chassis electrical grounding points
- Replace accessory belts
- Clean OMP lines
- Replace rear differential fluid
- Replace thermostat
- Clean / Straighten AC condenser fins
- Clean / Straighten oil cooler fins
- Inspect catalytic converter
- Clean / Inspect intake valving
- Consider / inspect all points in 90,000+ as well, many items fail early
~$130 USD in parts if you shop smartly.

90,000:
...all 30,000, plus any 60,000 not yet done, plus...
- Replace coolant bottle
- Replace radiator hoses
- Replace radiator
- Replace front O2 sensor
- Replace motor mounts
- Inspect clutch pedal assembly for flex / weld breaks
~$900 USD in parts if you shop smartly.
At 100k, anything original in the cooling system is really suspect and failure prone. It represents the biggest threat to your engine.
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04Green

iTrader: (1)

Best way to tell on a CAT is to drop the front an look at it.

I suggest something like an ultra gauge so you can tell where the mileage is worst, and collect some data.

Last time aligned? After suspension install?

Silver_Excalibur

iTrader: (1)

Super late response here.

I got the car aligned after the coilovers installed and I'm getting the car corner balanced here pretty soon. Always... so far maintenance that I have done since I bought the car is brake flush, multiple oil changes, New Coils, Plugs, and wires. Everything was oem besides the coils. I bought them from a local auto parts store (maybe thats the problem?). Diff and tranny flushes were also done with redline. Coolant hasn't been done yet. New filters... I don't know I'm running out of ideas. Almost traded the car in for a brz but adding 15k in additional debt because of gas mileage is just stupid. I did start running 10w40 after the sohn adapter I have no idea if this has an impact on gas mileage. I dropped it down to 5w30 for winter .

Silver_Excalibur

iTrader: (1)

I have a Wifi ob2 dongle for my iPhone with the dash command app. Would this work?

BigCajun

iTrader: (1)

Agreed.
It's a couple of bucks a tank.
Can't put a price on happiness.
I know my enthusiastic driving style wastes a lot of gas, but I don't care.
Don't mess with happy.