I bought a 85 gls se 'bout a month ago. I'm getting about 15 mpg I think somthing is wrong, I changed the air filter, oil, oil filter, .Do I have to change the O2 sensor? It just doesnt seem right that a 1.3L engine does so bad
Has anyone seen a increase in mpg with tubular headders and no cats?

 

Sounds like a temp sensor issue....

And yes, a free flowing exhaust is the first step to really letting these babies breathe.

 

now is it 15 in the city or all around?..i have a 12a with an exhaust...i get that in the city...it could also be your foot...

 

i got 23mpg with my last tank, and the way it looks, i will get more from this one

 

Damn, I'm getting about 12 to the gallon. But how can you drive a car like this, without putting your foot into it every chance you get? Hey, its like a drug, and drugs ain't cheap!

But yeah, I'm pretty sure an SE should be getting much better mileage than that...

 

I agree kentetsu. Every time you see that sharp bend and strait away you can just hear the 7 scream to be romped on!!!! Still, my 12a is getting 20 or so with my heavy foot syndrome..........

 

I got 18 city/highway... with a stock port 12a and holly 600.

 

I get about 24 hwy in my SE

 

I get 20/25 with a Dellorto and RE exhaust on my SA with a stockport 12a. You should be seeing the same or better with the FI SE.

 

I averaged 27.7mpg on my drive from Ann Arbor to the Mackinaw Bridge one day after the Furrin Group auto-x outside of Grand Rapids. Parking it at ~78 @ 3800rpm keeps the secondaries closed . I'd suggest replacing the O2 sensor, and the sensor that kentetsu suggested.

 

i got almost thirty on my way back from north carolina after buying the car, love mechanical secondaries. didnt open them once.


you sig says enkies, did you get new rims? if so you know the rules, gotta post pics!!1

 

I'm getting about 19 with city/highway mix. I have a SP 12A w/ RB holley setup. I always have my foot on it.

 

Need more information.


What type of driving?

Here is a link to my SE mileage thread-

https://www.rx7club.com/1st-generation-specific-1979-1985-18/fuel-economy-report-since-recent-mods-se-656700/

Also an update on my recent trip.

Made another trip out of town 161 miles one way.

When I got to my destination I filled up and the pump clicked off then the guy rounded it off to the next $ and that made it 4.2 gallons.

That would of been 38.1 MPG then the guy topped it off which went to 4.8 gallons which made the mileage 33.5 MPG.

When I filled up before I left I did not watch the guy pumping the gas to see if he topped off or he just did the usual round off so I can't confirm nor could I even believe that I got 38.1 MPG but the 33.5 is a definite confirm which is now over 2 MPG more than my last best.

On the return trip same miles same speed and driving habits the mileage was 31.6 MPG.
Now the outside temp going there was approx 89 Degrees and the temp returning this morning was approx 42 Degrees which would explain the lower MPG because of the denser air.

When I left I had dumped in some Denatured Alcohol in with the fuel as well as the Acetone so I don't know if the Alcohol had any effect either. Will try the same experiment when the weather warms up again.

This is also with the fuel with Ethanol in it which we just got here recently.

the only things I have changed since my last mileage checks are the following.

Changed the muffler out to a free flowing one.
Changed the trailing plugs out to some 2nd gen ones that I had lying around ( not sure if that had any effect)
Increased the tire pressure on the front tires to the maximum pressure of 44 PSI and the rears to 40 PSI.
Ran the Denatured Alcohol with the Acetone.

Also leaned out the mixture from the mixture screw for the FI but the only thing I remember that the setting does is affect the idle mixture and off idle to a certain point.

I do know that the muffler has the engine breathing better because after I installed it the throttle response was better. Had a old stock muffler off a 83 model on her before.

Now none of the above may have to do with the increase from my previous best of 31 MPG and may just be the hotter temp with thinner air that did the trick but still with the return trip of 31.6 it does not look like the Ethanol is going to affect my vehicle like they say it will with FI cars.

I still have some other things that I have not tried yet and hope that they will affect the mileage also.

All in all a 9.5 MPG increase over what the Stock MPG was from the factory is a incredible increase. :-)

 

thanks guys

 

i am tring to get better gas miles as well any idea how? and what o2s do i need to replace where are they and how many?

 

Did you read the link that I attached?

 

Well...I can give a more accurate record now that my acc. pump gasket doesn't leak every time I hit the gas....I am currently at 62 miles with my fuel needle just above the 1/4 down mark. Much better than before....this should get me around 240-250 miles on a full tank. This gives me an average of 16.8 miles to the gallon.

Not too bad with a 12A streetport w/ modified Nikki carb. I am running a 6A w/ 2nd gen mod, so I get a complete burn. Also running the full RB streetport exhaust.

 

what exactly does the denatured alcohol do? because ive got some i was going to use to remove paint, and it didnt work, so ive just been using it to remove RTV from my hands. but if this replaces seafoam, im pretty sure its cheaper.

 

what about removing the belt for the air pump, or pluming a by pass with a valve around the air pump?
a electric fan?
a electric water pump?
I plan to get tubular headders with a new O2 senser, no cats, and a free flowing muffler

 

Pay attention here this time.

We are asking questions to try and help you but you need to provide information.

1. What kind of driving and driving habits yielded the 15 MPG?

2. Have you replaced the plugs? Checked the air filter? Checked the tire pressures? Inspected the distributor cap and rotor?

Then also read the link that I have provided in my first response-

https://www.rx7club.com/showthread.php?t=656700

 

I dont drive too hard ,we dont have manny traffic lights, but we do have hills, but I only have to down shift maby on 2 hills,
I just changed the air filter and WOW I never saw one so bad so that should help,
I looked at the plugs they look good
tire press is 35 all around will bump it up to 44f 40 back
didnt check cap nad rotor yet

 

For preventive maintenance I would change out the O'2 sensor and the coolant temp sensor that is located at the back of the water pump housing.

Those 2 parts and also if you have access to Bg products get a can of the 44k and put it in the gas tank with 1/4 tank or less and run until empty. If you can't find the BG then get a can of Seafoam.

 

I averaged 26.5 for the last tank I checked. I honestly do not know how. I only had fresh plugs and a test pipe.

 

ok thanks, is 44k a cleaner?
I have to special order at my auto parts store so I'll prob. order over the net any suggestions

 

Yes it is a cleaner. You cannot buy it in auto stores, only some dealerships carry it and garages.