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91 fc non turbo, only 14 miles to the gallon

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Old 12-29-09, 04:31 PM
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the white comet
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91 fc non turbo, only 14 miles to the gallon

so after a round of Q and A with lucky 7 racing, they have pitched the idea that my injectors are fucked.


everytime i fill up its around 14 gallons but i only get about 200 miles before i have to refill another 14. when the car became mine, i already had the problem when everything was still stock. after the mods is still remains.

the car runs very strong, my 5th and 6th seem to open and the idle is stable and correct. and it only has 126 k original miles.

this post is not to disagree with their conclusion, but just to see if anyone has been in the same boat as me and what they did to correct it.

my mods include:

apexi intake 507-Z002
racing beat header, presiliencer, and racing beat turbo ii catback exhaust.

i have 17x8 and 17x9 5zigen zr520's and hankook RS3 tires on all 4s ( i am throwing this in because maybe the bigger and sticker tires then stock is ******* with my mpg also? its just a thought.)

everything i else i have shouldnt make a difference since its all suspension, bars, and sparcos.


so my question remains, averagely what do most people get on a non turbo 13b and if you have had the same problems as me what you did to correct such a wallet killer problem?
Old 12-29-09, 04:54 PM
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what are your driving habits like? how much time do you spend at WOT?
Old 12-29-09, 05:21 PM
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It's a Rotary, after all :)

Around town, foot into it pretty often?

14 mpg is about right. I get from 12 to around 18 (max) in town on my S5 vert.

Run a tank out on the highway, 65-70 mph steady. If you get 22-26 mpg, then everything is just fine.
Old 12-29-09, 05:30 PM
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Originally Posted by K-Tune
what are your driving habits like? how much time do you spend at WOT?
sorry i forgot to specify , most of the time monday - friday i drive about 15 miles one way to work and back. all highway. the times where i did keep an eye out for my mileage was when it was purely daily driving, not a canyon run or out with the friends. i cant say exactly but on the weekdays i probably dont rev past 6 and i cruise it in 5th most of the time at about 75 give or take.
Old 12-29-09, 05:36 PM
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Originally Posted by jackhild59
Around town, foot into it pretty often?

14 mpg is about right. I get from 12 to around 18 (max) in town on my S5 vert.

Run a tank out on the highway, 65-70 mph steady. If you get 22-26 mpg, then everything is just fine.
yeah i drove from LA area to san diego, and i probably got 220 max to my tank or something of that sort. nothing close to 22 -26 mpg =(
Old 12-29-09, 05:42 PM
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S5 vert with a streetport and no tuning I get 330 miles to a tank on highway. In the city with lots of revving? About 220-240.

If you keep your RPM under 3500 or so this keeps your secondary fuel injectors from keeping in and you save more fuel as well.
Old 12-29-09, 05:48 PM
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I would check your ECU codes, it can throw a code and won't necessarily turn on the check engine light.

it sounds to me like you might have a dead o2 sensor.
Old 12-31-09, 10:21 PM
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Originally Posted by eage8
I would check your ECU codes, it can throw a code and won't necessarily turn on the check engine light.

it sounds to me like you might have a dead o2 sensor.
after your post, i have replaced my fuel filter, o2 sensor and reset my ecu. hopefully this new year and next week these small things i have been doing finally pays off. happy new years everyone
Old 12-31-09, 11:34 PM
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Now look over and tell the fat chick she has to get out. Then your gas mileage will improve.

lol....


Happy New Year!
Old 01-01-10, 12:37 AM
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I get 15mpg average in my car.

HOWEVER, my friend gets like 25mpg in her fc... and that includes canyon racing. She gets like 30mpg highway. I don't know how she does it.
Old 01-01-10, 06:04 AM
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Originally Posted by funkjaw
my friend gets like 25mpg in her fc... She gets like 30mpg highway. I don't know how she does it.
Stock wheels and tires?
Speedo/odo correct?
Old 01-01-10, 09:40 AM
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Originally Posted by funkjaw
I get 15mpg average in my car.

HOWEVER, my friend gets like 25mpg in her fc... and that includes canyon racing. She gets like 30mpg highway. I don't know how she does it.
Something is fishy...
Old 01-01-10, 10:55 AM
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Have RX-7, will restore


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^^agreed.

at any rate, my first question would be how are the plugs and wires? how new is the fuel filter and air filter? with the large wheels and tires, how far off is your speedometer?
Old 01-01-10, 01:43 PM
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I swear guys no joke... it is insane I don't know how she does it. We have tested her MPG like 3 times... plus I tested it myself driving her car around all day when she let me borrow it.
Old 01-01-10, 05:57 PM
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Originally Posted by funkjaw
I swear guys no joke... it is insane I don't know how she does it. We have tested her MPG like 3 times... plus I tested it myself driving her car around all day when she let me borrow it.
well lucky her. i dont get anywhere near 30 miles per gallon.

after when i changed my fuel filter, i seems like some of the fuel that came out was mixed with water???? or something that was not fuel, iono.

as for other minor things to go along with my update, my idle is great and it has no hesitation throughout the rpms. quick question though, i have searched a few posts and most people get around 60 - 70 oil pressure at accerlation, my meter basically never passes 60. is that normal?

so for the update, the sparkplugs, wires, fuel filter, o2 sensor were all changed. my intake is brand new and my new exhuast has no leaks between gaskets from header all the way to the 2 mufflers. ill be starting a normal work week come monday and i will update my results.

thanks alot guys for the input, i hope these small things can fix my problem, i love driving it around and for winter, i dont like riding my bike but if this continues.....i think i might have too.

91 octane in so cali is not very cheap =/
Old 01-01-10, 06:00 PM
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Originally Posted by fastboy2468
Now look over and tell the fat chick she has to get out. Then your gas mileage will improve.

lol....


Happy New Year!
haha, sorry i dont have a girlfriend at this time, and my sparcos wont fit anyone that is not of average size.
Old 01-01-10, 08:32 PM
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If you are really concerned just have the injectors cleaned. I get an average of 18-20 mpg in my s4 turbo... driving fairly easy, with a new ignition parts, 5k on rebuild and fresh injectors.
Old 01-02-10, 01:48 PM
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If your oil pressure never passes 60 honestly it is nothing to worry about.
Old 01-02-10, 01:55 PM
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Why are you using 91 octane in an N/A? Crappiest gas you can get man, It works everytime. Have you checked your timing, or had a shop check it if you don't know how? Check it with a light.
Old 01-03-10, 02:37 PM
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I have an 86 FC, all stock (including wheels/tires), no ac or pwr steering, air pump still on, open diff, and my stock exhaust is full of holes and breaks in gaskets. I get 32/33 mpg in 5th going 76mph. 28 mpg when going 65mph.lol.

also save some gas by keeping my rpms below 2500 around town. lot of shifting but saves me money. . keeps the noise from my exhaust down too as I'll drive 30mph in 5th at 1k rpms.lol. I am so cheap but need the money for mods.muahahahahahaaaaa.

oh, and I use regular unleaded (87 I think? I don't pay attention).
Old 01-03-10, 03:34 PM
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not trying to thread jack or nothin but that fc with the fd front end on your sig^ is sick
Old 01-03-10, 05:55 PM
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I know, right? I almost threw up when I saw it... =P
Old 01-04-10, 01:13 AM
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back on topic guys, I just though it was unique. would look better if maybe they put on some FD rear wide quarters. keep the rounded look from the front fenders going. idk, I'm not doing it to my car. time to change sigs I guess! you guys should keep non related posts to PM's for future reference. just saying.

Update for this topic. started my FC today (I garage it in winter) and got a bunch of smoke from the muffler and smells sweet. think the coolant seals are going so my gas mileage will soon be 0 mpg. I wonder if, while it still runs, it will get worse mpg from this? anyone got an opinion?
Old 01-05-10, 05:51 AM
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When i first got my rx7 it was getting 11 MPG... i was LUCKy if i was able to pull 170 Miles a tank.. I hooked up the o2 i Pumped up my tired to 40 psi i think i had it up to 50 at one point. And huge thing is timing i played with that forever. And i ran injector cleaner for about three tanks.. And pulled the cats and air pump. and ran a strait pipe... Also Pull and wire brush or replace spark plugs very often.. makes a huge differance...

and i was back to 250. No shitting

Last edited by rx7_FREAKKK; 01-05-10 at 06:03 AM.
Old 01-05-10, 06:09 AM
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Originally Posted by funkjaw
I get 15mpg average in my car.

HOWEVER, my friend gets like 25mpg in her fc... and that includes canyon racing. She gets like 30mpg highway. I don't know how she does it.
It's not all that uncommon, just usually requires everything in good working order. I was able to do just about anything i wanted to my GTUs and keep it above 20 in the city/twisties/'spirited' driving. Interstate was 28-32, it can be useful if you've verified your intake, water, O2, TPS, etc are all on par. I'd generally float around the 15.5:1 area in closed-loop. I would usually set base timing about 4* advanced on all of my non-turbo cars as well. I also had no cats/free exhaust and moderately high EGT's at cruise. Was one of the better rx7's i had for gas, but most everything from bone-stock to turbo i've been able to keep easily in the 20's. Driving style probably plays the biggest role of all. Driving around a civic hybrid for a while made me an expert at maximizing my consumptin abilities though, couldn't take my eyes off that damn MPG meter (Probably not safe in the least).


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