Where is my gas going?

SNike05

Member
:
2002 Protege5
I've been reading all the miles per tank and mpg threads from the past and stuff. I do about 95% city driving and I have never ever got more then 19.5 mpg. I usually shift at 2500 rpm. Recently I installed a Injen CAI with the intention to improve this number. I am now getting 13 mpg consistantly. I reseted the ecu (take out negative terminal and hold brake for 15 seconds) The first few fill ups after the install were ~19 mpg consistantly. Now i'm getting 13 mpg. I'm getting quite pissed as gas is getting more expensive. Anybody have any clue whats going on here? I think I might just put the stock air box back on if I can't fix this problem.
 
I did the calculation using us gallons, i guess its a close estimate. Basically since I bought the car 3 years ago I have 20,000 KM now and I have never got more then 450 KM out of a tank, thats about 95% city driving. Since I put the CAI in I'm getting 300 KM out of a full tank. I think a hummer gets better mileage.
 
Damn, that isn't good... I normally get 400 - 520 in city... 500 - 650km on the highway... spark plugs need changing?
 
you could be right but is it possible for the mileage to drop so drastically just because of bad spark plugs?
 
Could? I'm no expert... but I would think that would cause miss firing and more gas consumption... i'm sure someone on here knows what it could be.
 
I'm gonna start filling gas at petro canada to see if its the gas at the station that I have been filling up since the install thats doing it. If that doesn't work then I'll reset the ecu again to see if that doesn't do anything. Anyways its late i'm going to bed i'll check the thread later tomorrow. Thanks for the advice lrhk.
 
Why did you think a CAI would improve fuel economy?
20mpg sounds about right for 95% city, especially if you are sat idling for long periods and/or there's lots of stop/start traffic.
13mog sounds horrendous. Sure you didn't miscalculate or spring a leak in your fuel tank?

You should try to get out on the highway occassionally for a long fast run to help clean the engine out. Your plugs may well be fouled.

I'd try a new set of plugs and a quality air filter in the stock box for starters.
Also, there are obvious things that can affect fuel economy like tire pressures, use of aircon etc.
 
run it higher than 2500, you might be bogging it and making it use more gas. Fuel economy of these motors also depends on the amount of load on the motor. My commute used to be all city and I got 30mpg consistently. I have a header, CAI, exhuast and modded intake manifold. Also make sure the CAI ias intalled properly and not leaking any air around the MAF. Check the pspark plugs too. If they are bad the MPG will suffer greatly.
 
This is what I would do, sit outside my house, hidden from view, with a night vision goggle set and a rifle, and find the ****** that is siphoning your gas... I have, cai, header, exhaust, and I get ~400miles per tank. Check ur fuel tank, as well as the lines, maybe you have a leak...
 
Change the plugs. 5 minutes to do, and easy. If you do not remember doing them, you oughta anyways. They are $5 for a set. Also, check your air filter. If it is clogged and filthy, replace it.

Make sure your oil changes are up to date. I got a mileage increase switching engine and transmission fluids to synthetic, but changing to that will not make a difference if you have another problem that is hindering your mileage.
 
I store my car for the winter for 4 months and only drive about 6-7000 KM (3800-4400mi) a year so I decided to use Royal Purple synthetic oil and gear oil, so I only change the oil once a season (8 months). Most of the time I shift at 2500-3000 but I do occasionally shift 4-5 when the need comes. I don't think I have a leak cause when we had our Nissan it had a leak and you could smell it right away when you got out of the car. I'm also gonna check the intake to make sure I installed correctly and I don't have any leaks also if the filter is clean. Maybe I will replace the filter cause my intake was bought used and charged I think he said 3 times already. I'm definitely gonna have a look at the spark plugs and wires. Thanks everyone for the advice I really apppreciate it.
 
and if you have a K&N filter, it lasts foever, just needs to be cleaned, and frssh oil applied. If you still have a bad ebay filter, toss it, go get a K&N.
 
Is the ECU reset really just 15 seconds? I thought it was 30.

Did you lose your radio presets when you did it? That'll tell you for sure.
 
Mike R said:
run it higher than 2500, you might be bogging it and making it use more gas. Fuel economy of these motors also depends on the amount of load on the motor. My commute used to be all city and I got 30mpg consistently. I have a header, CAI, exhuast and modded intake manifold. Also make sure the CAI ias intalled properly and not leaking any air around the MAF. Check the pspark plugs too. If they are bad the MPG will suffer greatly.

That would be my first guess too. only time I shift at 2500 is when i'm downshifting and I get between 26 and 29 mpg. I generally upshift at no less than 3500. I generally get about 360+ miles per tank.
 
SNike05 said:
I've been reading all the miles per tank and mpg threads from the past and stuff. I do about 95% city driving and I have never ever got more then 19.5 mpg. I usually shift at 2500 rpm. Recently I installed a Injen CAI with the intention to improve this number. I am now getting 13 mpg consistantly. I reseted the ecu (take out negative terminal and hold brake for 15 seconds) The first few fill ups after the install were ~19 mpg consistantly. Now i'm getting 13 mpg. I'm getting quite pissed as gas is getting more expensive. Anybody have any clue whats going on here? I think I might just put the stock air box back on if I can't fix this problem.

Release your E-brake! (thumb)
 
When gas prices went up this last time I started driving slower and not accelerating quickly and doing all the things that you're supposed to do to conserve fuel. The result was no improvement in fuel economy. So now I drive it like I stole it cuz its more fun that way.
 

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