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Old 12-09-2011, 02:36 PM   #1
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Angry bum gas mileage?

Just so you all know, i hate posting these stupid threads as much as you guys hate responding to them. But i have to know:
1.) why my stock 1.6 gets like 25 mpg....thats crap, my buddies modded 1.8 gets like 28
-Im sad about this :(
2.) Can you guys give me input on anything that can be tuned wrong robbing me of gas mileage? Because i have done alot of maintenance to it like
-new spectra air filter
-oil change
-ngk plugs and wires
-tranny fluid
-diff fluid (used lucus..my stock diff has 250k on her)
-im sure more that i cant remember. Theres probably a huge maintenance thing im forgetting to help it out.
Im aware i dont have tons of hp so im atleast hopping for semi decent gas mileage.....
Thanks
Its driving me crazy!
I also have 195/50/15s instead of stock whatever whatever, could that be throwing off my odometer and i actually am getting decent gas mileage?
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Old 12-09-2011, 02:41 PM   #2
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Quote:
Originally Posted by jhink92 View Post
Just so you all know, i hate posting these stupid threads as much as you guys hate responding to them. But i have to know:
1.) why my stock 1.6 gets like 25 mpg....thats crap, my buddies modded 1.8 gets like 28
-Im sad about this :(
2.) Can you guys give me input on anything that can be tuned wrong robbing me of gas mileage? Because i have done alot of maintenance to it like
-new spectra air filter
-oil change
-ngk plugs and wires
-tranny fluid
-diff fluid (used lucus..my stock diff has 250k on her)
-im sure more that i cant remember. Theres probably a huge maintenance thing im forgetting to help it out.
Im aware i dont have tons of hp so im atleast hopping for semi decent gas mileage.....
Thanks
Its driving me crazy!
I also have 195/50/15s instead of stock whatever whatever, could that be throwing off my odometer and i actually am getting decent gas mileage?
New 02 sensor
Is cat clogged or going out?
Tire pressure?
Driving habits?
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Old 12-09-2011, 02:48 PM   #3
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Unlikely the tires. Other than your right foot, the AFM and O2 are what will really determine how much fuel is going into the combustion chamber. You might want to try cleaning the AFM and maybe replacing the o2 sensor. If you have a bad water temp. sensor, it may tell the engine to change the a/f mixture as well...but most of the time, you'll get a CEL if one of those componants is really out of whack.

I average 22-25mpg with my driving habits. On a recent tank, and a trip in the mtns. I got ~32mpg. It's amazing how little inputs will affect mpg....everything from accelerating a little slower in traffic to cutting your interstate speed by a few mph. Top down also gets worse mpg on the highway.
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Old 12-09-2011, 03:19 PM   #4
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+1 for Doppelgangers post ^. I got 29.5mpg +or- .2 repeatedly from New Mexico to Nashville this spring driving my '97 none boosted. Did 80mph with the cruise control, every once in a while I goosed it just to kill the boredum or pass. Only an intake filter, exhaust, 205's, suspension, and just did a new O2. Oh, and no AC or powersteering might help MPG's. Little things do add up though. Proper tire air, clean intake filter, fresh O2 sensor, not driving with stupid sports team flags on your windows, or just oil changes are only 1% improvements (probably not that much). But a few 1%s turn into several % change. It's not worth the money to most if you just think of gas mileage. I just do that stuff as maintenance. A happy car usually lasts longer too.
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Old 12-09-2011, 03:22 PM   #5
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I'll second the o2 sensor and third the right foot. New sensors have netted me 20% increases in mileage on a couple of cars. Worst I've seen in my Miata has been low 20's and that's beating the **** out of it in the mountains. Usually see 27-28 with mixed use.
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Old 12-10-2011, 12:04 AM   #6
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Okay yea thanks guys, the o2 was replaced about 65k miles ago when the prior owner had replaced the engine with a long nose 1.6...the old 1.6 lost all compression and would burn all the oil driving down the road lol anyways so I'm gonna price that and probably replace, the water temp gauge reads acurately (I think) so how would you be able to tell besides for just replacing it. Also I'm getting my numbers from a tank fill to empty as to where I didn't beat on it at all, and mixed city/interstate. I generally cruise from 70-90 on the interstate. Thanks for being cool about this guys.
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Old 12-10-2011, 12:14 AM   #7
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Quote:
Originally Posted by matthewdesigns View Post
I'll second the o2 sensor and third the right foot. New sensors have netted me 20% increases in mileage on a couple of cars. Worst I've seen in my Miata has been low 20's and that's beating the **** out of it in the mountains. Usually see 27-28 with mixed use.
What about hard "city" driving? I've been getting low 20's for the last few fill ups, averaged 25ish city before that. Stock car.
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Old 12-10-2011, 02:15 AM   #8
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I slip the clutch at about 15-1800 and change gears at 3500
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Old 12-10-2011, 02:19 AM   #9
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My miata got about 14mpg. I drove the **** out of it all the time. Have you tried leaning out your out-of-boost fuel chart?
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Old 12-10-2011, 02:24 AM   #10
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I would kill myself at 14mpg...sounding like a fuel leak honestly! But also if my o2 sensor was bad wouldnt I have a check engine light?
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Old 12-10-2011, 02:37 AM   #11
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Quote:
Originally Posted by Gearhead_318 View Post
What about hard "city" driving? I've been getting low 20's for the last few fill ups, averaged 25ish city before that. Stock car.
The car is not my daily at the moment, so the mixed use I'm claiming is the occasional day here and there in town when I'm bored with the Protege, plus any fun time I have with it up in the hills. If I drove it daily, I'd surely have the loud pedal mashed quite a bit and get even worse mileage than I do now.
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Old 12-10-2011, 02:38 AM   #12
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Quote:
Originally Posted by jhink92 View Post
I generally cruise from 70-90 on the interstate.
I do believe we've identified your issue.

At 65mph, my turbo 1.8 used to get 30mpg. At 75-80mph, it would get around 23-24mpg. At 90mph, it would get around 18mpg. At 110-120mph, it would get around 11-12mpg.

If you want better fuel mileage, slow down.
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Old 12-10-2011, 09:42 AM   #13
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I mean I generally cruise at 70. The 95 part is when I get tired of slow *** holes and pass everyone for a few seconds. But generally I don't cruise on the interstate....ever, besides for when going to work which that's only one exit and generally ill only even do 65 then..damn car revs so hi lol
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Old 12-10-2011, 10:16 AM   #14
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-diff fluid (used lucus..my stock diff has 250k on her)
How many miles does the rest of the car have - ie motor?
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Old 12-10-2011, 11:00 AM   #15
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Stock my car got about 22 city, 23 highway (at 80). On the stock ECU at ~4000rpm it will go super rich, even at part throttle, so make sure you keep it below that. I made a 150 mile drive at 90ish with the top down and got 18mpg.

With cruise cells leaned out to 16:1 my car now gets 23 city, 29 highway, but still not as impressive as a lot of people seem to claim.
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Old 12-10-2011, 11:51 AM   #16
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Come to think of it I did have the top down a lot when I tracked the mileage....anyways it does smell kind of like its using more gas than it should. But to secretsquirrel the motor has about 60k on it. Rebuilt longnose 1.6
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Old 12-10-2011, 12:13 PM   #17
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I get about 25~26 city.

It did dip down into 18 mpg last month. But that also happened to be when I f-d my front 02 sensor and also had my cat go bad.
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Old 12-10-2011, 07:12 PM   #18
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Quote:
Originally Posted by pdexta View Post
Stock my car got about 22 city, 23 highway (at 80). On the stock ECU at ~4000rpm it will go super rich, even at part throttle, so make sure you keep it below that. I made a 150 mile drive at 90ish with the top down and got 18mpg.

With cruise cells leaned out to 16:1 my car now gets 23 city, 29 highway, but still not as impressive as a lot of people seem to claim.
This makes sense. I've got a lot of soot on my exhaust tip, maybe OP's exhaust tip is similar.
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Old 12-11-2011, 01:34 AM   #19
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I dont really have any soot...just a bit of average exhaust I would assume
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Old 12-11-2011, 01:37 AM   #20
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Could that have some of the reason as to why when trying to haul *** it seems like you get more power if you step on then release the throttle repeatedly instead of just mashing the gas to the floor?
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