Secondmessiah

the easiest way to get better fuel mileage is to trade it in for a civic, but assuming you dont want to do that

shift before 3000

dont bother with anything above 87 octane, esp on an NA (carbon buildup will kill your engine)

make sure youre calculating the gas mileage right (sounds demeaning but i can happen to anyone)

17 mpg city is the EPA ideal for a new 7, 12-15 is pretty good for real life

RETed

Nah, it's several factors...
My work place is only 3 miles from my house.
I don't usually jump on the freeway, thus it's all "city", stop-n-go driving.
I don't have a thermostat - just a gutted flange - so the engine barely gets up to temp along the way.
My TPS was "bad" - idle resistance was 2.5k-ohms with the screw fully backed out.
The car was averaging 13.0 to 13.5 mpg.

It doesn't matter anymore, as the stock crap is gutted, and the Haltech E8 is running beautifully now.


-Ted

RETed

Oh shoot, sorry about that!
I'm off by 0.6.

You're right - that's horrible gas mileage.
It sounds like a fuel leak to me?


-Ted

cdaleracer669

iTrader: (1)

am i the only one that sees little difference in gas mileage with a lead foot and a light foot? i get like a 1-2 mpg difference between the two. like 23 or 24 with a lead foot. 24 or 25 without a leadfoot...is there something wrong with my car?if so, dont tell me how to fix it cuz i like it. i can give it hell all tank and i still get good mileage.

ErixHvn

Intake Air Temp. S4's have one on the plenum near the Bypass air controll. A bad one caused mine to run overly rich and thus burn more gas than necessary.

Dunno if you had the injectors cleaned either but that could also cause poor atomization of your your fuel and bad mileage. What do your spark plugs look like by the way.

OMGWTHFBBQ

dont drive it

evelhalo

Dude, its a little pricy, but buy an electronic a/f sensor that attaches to your o2 sensor and ecu, and then youll be able to determine some things such as if all your fuel is combusting or not. also, you should check your compression. Uhh try rubbing the inside of your tailpipe, should all be carbon, no sticky residue (leaks) if your spark plugs are older take one out, see what color the electrodes are, if your housing and seals are solid they should not be black

evelhalo

you could also replae your air temperature sensor, and you could buy some 5minute engine flush to clean out any diposts in the engine

jeff_rx7

iTrader: (1)

i recently replaced the plugs, 5k ago or so. the old ones were browned nicely, but the trailing (i think) plugs were whitish - burning coolant?? it better not be my injectors, they were replaced in aug. i will look at the iat sensor, and my new o2 sensor is going in tonight. ErixHvn - is there any way to tell visually if the iat sensor is bad, or should it just be replaced?? Thanks for all the help guys
Jeff

speedholes

Either you're really bad at math... or somebody stole your engine and replaced it with a four-banger. Anyone ever hear of a 7 actually getting 30 mpg?

ErixHvn

Here ya go http://www.teamfc3s.org/main/factory...SYSTEMS_NA.pdf Check page 4A-81 for the IAT info. The whole section is a great place to start identifying any issues of bad gas mileage.
Hope this helps. Wouldn't hurt to pull the plugs again for a look since I dont know if the bad fuel economy started before or after the tuneup. What kind of injectors did you put in. Were they the stock size or was there any increase in the size of the injectors?

Jager

iTrader: (10)

Trade it in for a Geo Metro.

cloudlight69

im driving an 86 gxl na, i thought that i was all alone out there with the mileage too. after much research and many replies from this forum i found that i am getting better than average mileage on my car. I have a lead foot, i redline every shift, i just cant help but not to. for the longest time i watched my fuel gauge drop to empty in just 240 kliks. ild fill the tank and only get about 45 litres in her. my gxl has a 63 lite tank so it clued me in that even though the gauge is below the double lined empty, i probably had a few more kliks in her. so i let her ride one week on empty and was able to get an additional 90 kliks out of her before i got scared and filled her up, which mind you my tank would only allow 50 litres in. so,if you are getting around 200 a tank that is normal, driving fast or granny like. and if you are feeling dangerous, maybe drive her full to empty ( with a jerry can to save you ) to see what your mileage is. you are not alone....

rxspeed87

I'm fairly good at math. to be honest I have heard of it a few times with some other members as well. it was a good long trip no stop and go just out on the road.

as far as the motor if you really want I can take pictures. it looks like a rotary to me.

jarred

interesting to say the least...

drft_180sx

I haven't read the entire thread, so maybe it has been mentioned? But i know i used to get milage like that on my N/A. But then I rebuilt all for of my brake calipers, new rotors, and pads, and now i get 20mpg. Just a thought?

Meaning i had seized brake calipers, that were dragging....maybe you can make sure your brakes aren't dragging. The hand brake should be going up about 5 clicks easily...and well if the fronts are dragging, u would notice by lack of acceleration and seriously messed up rotors...

Jahan

CarmonColvin

When I first got my current daily driver running (back in 2003) I was only getting around 220-230 per tank (approx 16+ gal for full refill, ~14mpg). I thought my poor gas mileage was due to the engine being my first rebuild. A few months later the drive shaft started making horrible popping noises. Like an idiot I drove with the noises for another few months. When I finally swapped out the driveshaft I discovered that the rear u-joints on the old one was so hard to flex that I almost could not get it out of the car. It was impossible to flex with just my hand. Where as the new one was very easy to move and flex. Immedietly my gas mileage jumped to over 300 miles per tank (~19mpg). The drive shaft was binding up due to the seized up bearings.

It is a long shot because it is more logical you have engine/fuel related issues but it might be worth checking to see if you have a driveline issue that is sucking up all of your power.

1995hoo

The advice about keeping the revs down is one of the most useful things you can try. It makes a big difference in any car.

I have a question for anyone who knows, though. We've all seen the various commentary on the "using A/C versus using windows" issue, and a lot of the commentators conclude that it's generally a wash. How about driving with the convertible top down versus using the A/C? It seems to me that one might experience less drag with the top down (assuming the wind blocker is also down), especially if the tonneau cover is in place (OK, I never use mine), than one would experience with the top up but the windows down. Does anyone know? My inclination is to minimize my A/C use in this car anyway to try to put off the day when I have to recharge it lest I have some issue on the Freon.

(EDIT: I should add that it's more out of intellectual curiosity than anything else. I didn't buy an RX-7 out of a desire to get super fuel economy, and I love driving it with the top down and won't leave the top up just to save fuel!)

speedracer2235

Ok Ive got one for all of you.
86 sport
full interior, 6 pt roll cage, no A/C, 5 lug, power notta
suspension is a full racing beat setup, non aggressive alignment, toe eliminators etc
the motor is N/A street port intake side no exhaust port but silencers removed, UIM 89+ with the secondary thingy wired open, LIM gutted no 6ports whatsoever and I ran a dremel tool through it and smoothed everything out. all egr stuff was gone, awax removed, throttle body was dremeled cone filter on the end. All run on the factory computer. drive belt was only running the water pump and alt.
racing beat header, R/B presilencer, N1 full cat-back (sounded awsome)
would run or out-run a stock TII, run with a eclipse turbo

I considered this thing my track car. I drove it to and from the track.

HOW ABOUT 30MPH ON THE HIGHWAY UP TO 90MPH!!

I did this not once but on a regular basis. I loved this car but alass father time took her from me. (the bottom rusted out) 20B10AE can attest hed put 2 tanks to my 1 with his TII.

raptor22

1995: I am pretty sure you are better off with the windows down and the top up. With the top down, you have a HUGE low pressure seperation bubble behind the window, that basically sucks the car backwards.

That said, the vert has a big seperation bubble behind the raised top as well, but I am pretty sure it wouldn't be as much of an issue as the windshield, since the rear end of it isn't faired in at all..


--Alex