# Mileage problems
**URL:** https://forums.speedlife.net/t/mileage-problems/124138
**Category:** SON240sx Automotive
**Created:** [May 3, 2009, 8:44pm UTC](https://forums.speedlife.net/t/mileage-problems/124138 "2009-05-03T20:44:06Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Wongger](https://forums.speedlife.net/u/Wongger)
#### Post date: [May 3, 2009, 8:44pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/1 "2009-05-03T20:44:06Z")
Ok, so I just came back from kitchener today. From London to Kitchener its about 45- 1 hour. It cost me 20 dollars in gas. Going 110-120 there and back. I feel this is ridicules. It costs me 45 dollars to fill my tank at about 85 cents. Last year it cost me 30. not sure how that works? but it is.
I just changed my fuel filter, I have new fuel lines, checked for leaks, saw none. What else can I do? This is pissing me off.
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### Author:  [@AhmadG](https://forums.speedlife.net/u/AhmadG)
#### Post date: [May 4, 2009, 12:36am UTC](https://forums.speedlife.net/t/mileage-problems/124138/2 "2009-05-04T00:36:35Z")
Im in the same boat as you man, 400kms to a FULL tank driving efficiently, mostly on the highway at 110-115km/h.
Try fuel filter, injector cleaner, seafoam in oil/gas/vacuum hose, O2 sensor, coolant temperature sensor, check for vacuum leaks again, thermostat, plugs, wires, compression test, check for plugged cat, try hooking up a wideband or connect your consult port to a laptop with the appropriate software and cable. Check timing, and if the knock sensor harness is properly wired up.
Hope that gives you a list of what could potentially be wrong. I did almost all of the above, still, same shitty gas mileage and running rich…this is on a stock KA24DE btw.
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### Author:  [@R33](https://forums.speedlife.net/u/R33)
#### Post date: [May 4, 2009, 11:20am UTC](https://forums.speedlife.net/t/mileage-problems/124138/3 "2009-05-04T11:20:13Z")
get a honda
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### Author:  [@Wongger](https://forums.speedlife.net/u/Wongger)
#### Post date: [May 4, 2009, 3:04pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/4 "2009-05-04T15:04:57Z")
Alright well, It just started this year. I put my car away for the winter, now shes a gas monster. Im thinking that it may be my spark plugs though. My exhaust smells funny, thinking its not a complete combustion, and that’s where my gas is going.
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### Author:  [@XSNRGE](https://forums.speedlife.net/u/XSNRGE)
#### Post date: [May 4, 2009, 8:36pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/5 "2009-05-04T20:36:29Z")
Is your EGR working? I know when my CEL goes on (EGR function), my mileage drops similarly to that of yours. When my CEL is off and my EGR is working properly (not stuck), I only use **LESS** than 1/4 of a tank to go from Guelph to my place in Ajax (roughly 130-140 kms)
This is on an engine that’s got about 273,000 km’s and missed an oilchange by almost 10,000 km’s and has bad compression (150-150-135-150) LOL
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### Author:  [@curentS14](https://forums.speedlife.net/u/curentS14)
#### Post date: [May 4, 2009, 8:51pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/6 "2009-05-04T20:51:21Z")
Ya i took out my EGR and all the emissions crap i dont need. get WAY better gas millage. just move somewhere you dont need an e-test 😉
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### Author:  [@Wongger](https://forums.speedlife.net/u/Wongger)
#### Post date: [May 4, 2009, 8:57pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/7 "2009-05-04T20:57:15Z")
Ok, well im sorta new to cars. What is EGR? and what does it do? And what is CEL? lol Sorry. I just checked all my spark plugs, they all look regular. Could my timing be way off? Ive also been getting a weird Idle. In neutral it usually idles at around 700-900, but sometimes it drops down to 400-500. Not sure what that is either. Any advice would be helpful.
thanks
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### Author:  [@sidewayz240](https://forums.speedlife.net/u/sidewayz240)
#### Post date: [May 4, 2009, 9:12pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/8 "2009-05-04T21:12:07Z")
Exhaust gas resirculation and Check engine light.
Timing isnt the cause. I cant really help you any further other then just repeating what been suggested.
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### Author:  [@AhmadG](https://forums.speedlife.net/u/AhmadG)
#### Post date: [May 5, 2009, 6:00am UTC](https://forums.speedlife.net/t/mileage-problems/124138/9 "2009-05-05T06:00:32Z")
I have no CEL whatsoever…
My EGR was tampered with by a shop when doing the e-test upon purchase of the car. They apparently cleaned it out and made sure it wasn’t getting stuck. The car then passed the e-test.
And R33, stop being an idiot with the Honda suggestion. lol These cars are known to be pretty good on gas (over 25mpg mixed vs. the 18mpg mixed I’m getting).
XSNRGE, I envy you… I get like 100km for a quarter of a tank, using cruise control at 110km/h on the highway, with a rebuilt KA that has 5,000kms on it so far. lol faaaaaaack.
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### Author:  [@Polar\_s13](https://forums.speedlife.net/u/Polar_s13)
#### Post date: [May 5, 2009, 10:03am UTC](https://forums.speedlife.net/t/mileage-problems/124138/10 "2009-05-05T10:03:37Z")
I dont know why your posting how much you tank up for you should be putting how many litres of gas you tank up(our tanks are 60L).
And i get 500-550km on a tank driving like a jackass…lol
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### Author:  [@educated\_Idiot](https://forums.speedlife.net/u/educated_Idiot)
#### Post date: [May 5, 2009, 10:13am UTC](https://forums.speedlife.net/t/mileage-problems/124138/11 "2009-05-05T10:13:08Z")
Peterborough to London and back. 690 km on less than a full tank.
Jack your car up and make sure you wheels spin ok. You could have a bad wheel bearing.
Make sure all of your brakes are retracting properly and the sliders aren’t seized up.
Air filter?
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### Author:  [@AhmadG](https://forums.speedlife.net/u/AhmadG)
#### Post date: [May 5, 2009, 11:56am UTC](https://forums.speedlife.net/t/mileage-problems/124138/12 "2009-05-05T11:56:05Z")
When the car is in neutral it GLIIIIIIIDES, so my rolling resistance is minimal (bearings, rubbing calipers…etc), but when I’m in gear and I let the throttle go it slows down considerably faster. Under partial throttle in 5th on the highway it HOWLS, only between a small range of throttle input, nothing below that and nothing above that. I will never understand this car.
In the mornings when everything is cold, when I’m in first gear and I let off the throttle, it feels like I stepped on the brake, lots of resistance. Anyone care to explain why? I was assuming its the high viscosity of the tranny and engine oil causing more resistance when cold. But the howling, I’m completely stumped. Resonance frequency of leaky exhaust??? No clue. lol
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### Author:  [@87s15lt1](https://forums.speedlife.net/u/87s15lt1)
#### Post date: [May 5, 2009, 11:58am UTC](https://forums.speedlife.net/t/mileage-problems/124138/13 "2009-05-05T11:58:45Z")
no one ever seems to think about your tire sizes and gear ratio’s
gawd!
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### Author:  [@Wongger](https://forums.speedlife.net/u/Wongger)
#### Post date: [May 5, 2009, 6:23pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/14 "2009-05-05T18:23:35Z")
Checked wheels they spin fine. The rear calipers are new. My front may be seized. Need to check that I guess. Air filter is brand new.
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### Author:  [@KA24Power](https://forums.speedlife.net/u/KA24Power)
#### Post date: [May 5, 2009, 6:37pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/15 "2009-05-05T18:37:29Z")
check your ecu for any codes. usually a good place to start and if you’re seeing a mileage drop that big i’d guess something has gone for a shit
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### Author:  [@AhmadG](https://forums.speedlife.net/u/AhmadG)
#### Post date: [May 6, 2009, 12:49am UTC](https://forums.speedlife.net/t/mileage-problems/124138/16 "2009-05-06T00:49:28Z")
> [@which wine to get?](https://forums.speedlife.net/t/which-wine-to-get/21822/49):
>
> no one ever seems to think about your tire sizes and gear ratio’s
>
> gawd!
I multiply my odometer and speedometer readings by 1.031 to compensate for the increase in tire circumference going from 195/60/R15 to 225/45/R17.
Go here to calculate the difference, its so useful, and quick.
[http://www.miata.net/garage/tirecalc.html](http://www.miata.net/garage/tirecalc.html)
I did a 5 spd. swap, but the final drive ratio should be identical to a manual car. 5th is a bit shorter than O/D on the auto, I’m doing 3350rpms at 120km/h. Seems a bit too high to me, that’s halfway to redline, cruising on the highway…
I wanna scan my ECU, I have to save up some money to pay off debts and then buy that consult cable and software. Debts are obviously car related lol.
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### Author:  [@91S131](https://forums.speedlife.net/u/91S131)
#### Post date: [May 6, 2009, 7:56am UTC](https://forums.speedlife.net/t/mileage-problems/124138/17 "2009-05-06T07:56:11Z")
we all do around 3500 revs at about 120Km/h AhmadG
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### Author:  [@Jedi\_Car\_Fan](https://forums.speedlife.net/u/Jedi_Car_Fan)
#### Post date: [May 6, 2009, 1:14pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/18 "2009-05-06T13:14:25Z")
> [@which wine to get?](https://forums.speedlife.net/t/which-wine-to-get/21822/49):
>
> no one ever seems to think about your tire sizes and gear ratio’s
>
> gawd!
Well considering all USDM 240’s from 89-98 all have the same tranny/diff gearing and all SR20 equipped JDM/EUR also have the same gearing. The only way it would change is with a CA18 Tranny, Diff etc… I’m 90% sure even the RB20 has the same gearing “tranny wise” not sure about the diff"
Tire size… sure.
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### Author:  [@AhmadG](https://forums.speedlife.net/u/AhmadG)
#### Post date: [May 6, 2009, 9:30pm UTC](https://forums.speedlife.net/t/mileage-problems/124138/19 "2009-05-06T21:30:26Z")
Diff’s have different ratios. Like the Q45 diff or J30 diff. A lotta open differs swap them in. I believe both of them are taller. There is a thread on Nico about all the final drive ratios of almost every diff you would consider swapping into an S-Chassis.
But for most people with the stock diff, its just a small percentage correction they have to make to their speedometer & odometer, and it is directly related to the increase or decrease of the tire diameter.
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### Author:  [@87s15lt1](https://forums.speedlife.net/u/87s15lt1)
#### Post date: [May 7, 2009, 5:52am UTC](https://forums.speedlife.net/t/mileage-problems/124138/20 "2009-05-07T05:52:54Z")
> [@On another topic](https://forums.speedlife.net/t/21873/4):
>
> Well considering all USDM 240’s from 89-98 all have the same tranny/diff gearing and all SR20 equipped JDM/EUR also have the same gearing. The only way it would change is with a CA18 Tranny, Diff etc… I’m 90% sure even the RB20 has the same gearing “tranny wise” not sure about the diff"
>
> Tire size… sure.
You do know, that when you change your tire size, you change your “True final drive” right?