I have a 93 Mazda Rx7 that is getting around 200miles per tank. I have only owned the car since December so I do not know the history of it. It does however have a 3 inch exhaust pipe from header back (I THINK) it does have a glasspack or high flow cat. I am not sure if it has the precat or not. I am also not sure if it has the stock downpipe. The other day I noticed the downpipe glowing orange at night after warming up for about 5 minutes. It does have the AWS connecting and working. I do not smell a strong gas odor coming from the tailpipe it just smells like a little bit of burning oil. Most of my driving is done on the interstate at about 80 and some surface streets around 60. I drive the car 40 miles a day. It was 20 something degrees outside at the time. So to my real question what should I look at replacing first? O2 sensor, injectors, engine temperature sensors all three of them, fuel filter? Please point me to the a tutorial on how to do those if you know of one. I am slow at using the FSM.

 

I suggest you change the fuel filter as a matter of maintenance, and at your next convenient time, get the injectors pulled for ultrasonic cleaning. Glowing dp during warmup suggests you have an injector dumping fuel.

Dave

 

I usually do a little more then 200miles per tank... sometimes less, sometimes more..... its all relative to my foot

has for the downpipe glowing... that ain't good..... do what Dave says.

 

I can consistenly get over 250 miles a tank around town, and much more on the highways. Granted if I go for some spirited driving it significantly drops these numbers.

I have a downpipe, RB single tip among other mods. I'd go with Dave's advice because 200 miles a tank is real low.

 

200 miles isnt that out of wack, probably just needs a tune and new filter.

 

Yeah.. I'm getting right around 200 miles a tank as well.. never really questioned it. Though I do have more than just the basic reliability mods...

 

I'd also replace the O2 sensor - they only last ~50 K miles. You can get a generic one.

Here's a thread that relates to that:

https://www.rx7club.com/showthread.p...ty+improvement

 

What is your MPG? You never said. It depends greatly on how you drive the car. I get 15-18 MPG average on the road but tracking the car drops it to about 4MPG

 

I averaged 15mpg mostly city and 22mpg highway on stock injectors, m2 stage III ECU, and 11psi.

I say replace the O2 first, its super cheap, but kind of a pain in the *** to change, depending on what tools you have.

 

miles per tank isnt the best indicator as different people fill up at different times. I hate to let my tank get below half, so no way will I ever get over 200, some may have no problem going right down to empty so 300 could be easy!

calculate your miles per gallon, that will mean much more to us

 

What kind of gas mileage do you think you are getting while your car sits there idling to warm up? Probably not too good . If all of your miles are around town, and you are getting on it quite a bit, you will only get around 10 mpg.

Most likely, you have used around 14-15 gallons to get your 200 miles. That's not so bad.

 

I used to consistently get 225 - 275 miles per tank in mixed driving on my last mostly stock FD. Its a different story with the current one.

Along with what dgeesman said, you might want to change your spark plugs (stick with the factory plugs) and maybe get some new stock (NGK) plug wires, change the oil, air filter and O2 sensor. Assuming you haven't already.

You might want to spend some time reading the FAQ thread stickied in the forum too so you can identify what exactly your mods are. Its always a scary thing when someone doesn't know if they have a muffler or a cat in their mid pipe...

 

LOL, I get 150 to 170 miles per tank. I figured it was my foot's problem, but hmmm, makes me wonder now. I have DP, MP, 3" exhaust, intake, Intercooler, and other goodies, runnin on non seq twins.

 

I wonder if there's an hybrid conversion kit for my FD, I'm very sensitive about my MPG

haha

Seriously, 200 miles per tank is relative to how low you let it drop before you fill it, but it's definately not that bad.

Heck, I sometimes get these numbers... in KILOmeters! 200km per tank I mean. I can also get 300 or 325. Really depends a lot of factors including my right foot, the humidity, air thickness etc...
I won't let my tank drop below 1/4 though.

 

Have your downpipe glow during/shortly after startup is normal if you still have AWS. My suggestion, disable it if you no longer have a pre-cat because that's what it was meant for.

 

I just bought my FD about 4 days ago and i am only getting about 105km (65.2 miles) per 1/4 tank, but so far i have only gaged the first 1/4 tank. I have been driving it like a baby keeping it under 3rpms trying to gage what my actual gas usage is.

man for a 20g tank that mpg is CRAZY i might as well be driving a big truck, but i wouldn't rather drive anything

I know for sure that i need to get it tuned, and i am about to start regular maintenance, fuel filter, oil change, tuning, tune-up, 02 sensors, and so on.

o by the way does anyone here know if this car gives you a warning light of a bad o2 sensor?

thanks

 

I get about 220/tank driving strictly street and about 330/tank driving mostly highway.

 

I really, really wish people stopped reporting miles per tank. It is an absolutely meaningless number.

I wonder if all of the people reporting miles per tank actually know the FD's fuel capacity. If you don't know this number, how could you possibly think you are conveying useful information?

I have never managed to get more than 75% of the nominal capacity into my car even when the gauge reads empty. This number will vary significantly by driver.

 

You're never going to get great gas mileage out of a rotary. Remember it needs 1.3 times the amount of fuel as a comparative piston motor. I think the most I ever got was around 250 with a single turbo setup and all highway driving. Also, the most fuel I ever put into it was about 18.2 gallons and the car was sputtering at that point. You can't burn the entire 20 gallon capacity of the stock tank.

 

I must have serious issues with my lead foot disorder, because I barely break 100 miles after a full fill-up. At about an average of 18 gallons per fillup, that's between 5 & 6 miles per gallon.

It's been that way since I've owned the car and the parts that I've changed that could affect mileage are the following:

Adam C intake, Downpipe, midpipe, RB dual tips,
Fuel Filter, Fuel pump, O2 Sensor, plugs, plug wires, powerFC

Anything else that I should change? I'm pretty sure I have the original injectors. Could that have a huge effect?

 

To get mileage under 10mpg, IME you have injectors dumping abnormal amounts of fuel.

You can jump to a conclusion, remove the injectors and get them ultrasonically cleaned, or find someone who can wideband the car to know just how rich the car is running.

Dave

 

If it was running rich, wouldn't my car be smoking abnormally? Even for a rotary, mine doesn't smoke much at all.

 

When you fill up after 100 miles and it takes 18 gallons, it's got to be going somewhere. That's 3x the gas that a normal gas-hogging FD will use - smoke or not it's quite easy to justify spending money to solve the problem.

Dave

 

I agree...are there any step-by-step instructions on how to remove the injectors?

 

You still don't know your Miles Per Gallon, although it's not too tough to find:

1. Start with a completely full tank
2. Zero out your tripmeter
3. Drive until nearly empty
4. Fill the tank completely full (try to use the exact same gas station both times)
5. Write down how many miles are displayed on your tripmeter.
6. Divide the miles you travelled by the gallons of fuel you used. For instance, on my previous tank, 192 MILES / 13.98 GALLONS = 13.7 MPG


-s-