Bad Gas Mileage for N/A 2.3

kevinspann · Dec 15, 2006

My little 2.3/automtic gets only around 18 - 20 mpg at best. I dont drive on the highway, but this still seems like bad MPG. I seem to read alot about turbo cars getting 23 - 25 mpg, and i want that.
Would have too much timing cause something like this? I think i have to much because the car idles at aroud 900 rpm after warming up. Which way do i turn the distributor to reduce the timing anyway? I suppose a timing light would help.

I feel like such a noob

Do you guys have any suggestions as to what i could do to help my mileage?

Red_LX · Dec 15, 2006

Actually it's supposed to idle at 900-1000 rpm.

If you're doing a lot of city driving, you may just be getting that bad of mileage anyway. I'm driving a '94 Tempo right now (2.3L, 5 speed), when I lived outside of town and was driving 30 miles to work every day I was getting close to 30 mpg. Now I live in town and do a lot of city driving, and the car is really only averaging around 20 mpg. It sucks, but unfortunately I don't think there's much I can do about it.

Anyway, you might try doing a full tune-up...what year is your car? New plugs and wires at least, if it's a pre-DIS car replace the cap & rotor as well. Also try running some injector cleaner through it. Might wanna look at a fluid & filter change on the tranny if that hasn't been done in awhile also. Could also be your O2 sensor going bad.

kevinspann · Dec 15, 2006

Its a 1990. I replaced the plugs about 6mos ago, the rotor and cap when i got the car a couple of years ago. The 900 - 1000 rpm idle seems high especially when compared to new cars that idle at 750ish even if they arent warm. The tranny fluid and filter need to be changed, but i want to go to a stick anyway....but that'll be a whole 'nother thread...and the o2 sensors probably need replacing anyway, i think theyre original

Shawneebear93 · Dec 16, 2006

900-1000 RPM idle is normal as mine is in that area and I've been driving my '93 2.3 for 4+ years. These cars (2.3 Mustangs) got 22 MPG from the factory (and that's obviously under perfect conditions). I average ~20 MPG in the city but ~30 on the highway ... so you're about average.
Some claim to have gotten 26 or so MPG with a cold air intake but I cannot attest to that.

Red_LX · Dec 16, 2006

750 RPM? I don't know of any four cylinder cars that idle that low. In fact most 4 cylinder cars (especially imports) idle a good bit higher than 1000 RPM.

Anyway, if it's been a "couple of years" since you replaced the cap & rotor, you might look at doing that again.

I never drove my old '90 in the city much so I can't tell you much about the mileage it got doing that. However between a mix of a little city driving and a lot of open road driving, I used to average 29-30 mpg with it...until it overheated and cracked the head, after that the best I ever got was 24-25 mpg even on the highway.

Mr. Rustypwnz · Dec 16, 2006

I think your getting about right mileage, our 93 notchieback gets about 22-23 in town and it only has 23.5k original miles in mint shape driving like a 150 yearold grannie.

Stinger · Dec 16, 2006

Sounds about typical for mileage.

And yes some imports idle lower...most mid-late 90's civics idle around 650-750 but if you crank a 2.3 down that low it runs too rough...amazing what a couple years of technology will allow.

kevinspann · Dec 19, 2006

Red_LX said:
750 RPM? I don't know of any four cylinder cars that idle that low. In fact most 4 cylinder cars (especially imports) idle a good bit higher than 1000 RPM.

Anyway, if it's been a "couple of years" since you replaced the cap & rotor, you might look at doing that again.

My mom rented a stratus that idled around 750-800 rpm....

The capa nd rotor were replaced in Sept '04 after i got the car, so its been ~2 years and 4 mos ago, and they only have 3000ish iles on them

65ShelbyClone · Dec 23, 2006

kevinspann said:
My little 2.3/automtic gets only around 18 - 20 mpg at best. I dont drive on the highway, but this still seems like bad MPG. I seem to read alot about turbo cars getting 23 - 25 mpg, and i want that.

25mpg is a highway figure for the turbos. Some get better, some worse. My SVO only averages 22-24 with a best of maybe 26mpg(at 70mph/3000rpm). 26mpg was the rated economy from the factory. I've heard of people topping 30mpg in the TurboCoupes, but those are longer and more aerodynamic.

The 2.3s are supposed to idle between 900 and 1000rpm.

Stinger said:
And yes some imports idle lower...most mid-late 90's civics idle around 650-750 but if you crank a 2.3 down that low it runs too rough...amazing what a couple years of technology will allow.

I've never seen them idle that low, but I don't spend much time around them either. I have a '94 Toyota truck with the 2.4L 22RE and it idles at 750rpm, which is the spec on the hood sticker. It also gets 31mpg on the highway.

kevinspann · Dec 27, 2006

slow95gt said:
I think your getting about right mileage, our 93 notchieback gets about 22-23 in town and it only has 23.5k original miles in mint shape driving like a 150 yearold grannie.

I want your car......

After about 110 miles, im at less than a half tank, and 1/3 of those miles were highway... im thinking thats bad...unless the gauge is wrong. When i fill up the tank and start the car it goes up to a little over full, but when i cut the car of it dropps to 3/4 of a tank, but when i start it again, it raises right back up...and my temp, "oil pressure", and gas guages pretty much keep their last readings, is that normal?

I am glad to hear that the idle is where it shoud be,although i think it take to long to get there, its usually around 1000-1100 for a while, then it settles down, but oh well i guess thats just how it is

BTW my friends calivier idles around the same 900ish rpm

Jimmy2Times · Jan 11, 2007

The first thing I would do to improve your mileage is to change your O2 sensor. It's $40-$50 well spent, especially if it's saving you gas money in the long run and possibly saving your cats from fouling. You can also check your fuel pressure by hooking a gauge up to the schrader valve on your fuel rail. If your pressure regulator has failed, you could have way too much pressure resulting in your injectors squirting too much gas. I know 5.0's are supposed to be in the high 30's, low 40's on fuel pressure at idle... not sure what the 2.3 should be at.

For the record, my 1987 2.3 idles at around 900 too.

ethangsmith · Feb 3, 2007

My 86 Capri (carbed) got 18mpg in town and 30mpgs on the highway before my conversion. I don't know what it gets now. It idles at 750, which is factory spec per the hood VECI decal.
My 88 Mustang gets 20mpgs in town and 30mpgs on the highway. It idles at 700.

Jquintel · Feb 15, 2007

Sounds about right,

doesn't the 90 auto also come with OD?? are you driving in OD?

just curious, i used to not drive in OD and after i started to drive in OD it made a significant increase in mpg

i usually run 20-23 mpg, except in the winter where i have to let my car warm up considerably longer...

boo

glowstang93 · Apr 11, 2007

I get 19-20 in town. I just checked it tonight and it was calculating 22.4 mpg. The increase was due to a 90 mile round trip on the highway. I used to get 30 mpg going back and forth to work on the highway.

Stableboy · May 4, 2007

Funny, I was going to ask same type of question. This is the first full week I got to drive my car. 1990 Auto/convert. I drive 18 miles each way on I 95 doing 70-75 and then 5 miles stop and go to work. The gas gauge doesn't ever read above 1/2 even when topped off, so at 170 miles I filled again. It took 8.2 gallons. About 20mpg. Much lower than I got in my other 4 bangers, but this is heavier. Also, how big is tha gas tank, so I can guestimate miles to empty?

ethangsmith · May 4, 2007

It should be the 15.7 gallon tank. With an automatic, you get the 3.73 rear gearing so it will rev higher and consume more gas than the T5 5 speed setup (it has 3.55 gears) especially above 65mph. Your gas mileage isn't that off though. Maybe give it a tune up, new air filter and new oxygen sensor. See what that does for it. I put a K&N filter in the mustang (1988, automatic) and saw an average increase of 2.5mpgs per tank.

kevinspann · May 4, 2007

I didnt know that the 5spds had 3.55s, i guess that counteracts the 0.79 5th gear that the 4cyl t-5 boxes have. My gas mileage was lower than the 18-20 mpg that i wrote in my initial post, but i think it may have been due to the fact that my shoes are dragging against the drums....which i think is due to a stretched ebrake cable...but not to worry, SN95 brakes will be coming soon

Shawneebear93 · May 7, 2007

The T-5 has 3.45s not 3.55s - not a huge difference but just for clarification.

Bad Gas Mileage for N/A 2.3

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