First I want to apologize if this is a repeat question. The firewall filters here at work will let me come to this site, but block the search page for some reason.

My question is this: what are the main culprits in poor fuel economy? (told ya it was a noob question)

I have a 2.8 V6 with 78,000 miles. I've recently had a tune-up, and put injector cleaner in the tank. I know I have a small exhaust leak, though I have no idea if that would affect gas mileage.

I'm only getting between 17-20 mpg right now, and with gas prices rising I'm looking at having to sell the Fiero to buy a car that I can afford to keep fuel in. I really don't want to sell, but I'll do what's needed to keep food on my children's plate.

Any ideas would help.

Thanks,

FP

If the car is tuned properly and no sensor problems, the biggest low gas milage cause is your driving technique. You may need to get a computer read out to see if all is working correctly to see if the car is running rich, timing set correctly.

If you have an automatic transmission you may expect 27 mpg (highway) on a good day. If you have a manual five speed, you may see in the low 30s mpg. This assumes light foot driving.

Thanks for the info. It is a manual 4 speed tranny, and I've been purposely driving easy to conserve fuel. (No jackrabbit starts, and never above 60 on the highway) I guess I need to take it in for a diagnostic hookup.

Thanks again. A "+" for you.

When you had your tune up, did they replace the O2 sensor? If they didn't you should, it will help increase your gas mileage if it is fresh and working properly.

If you have an old laptop with a serial port you can run your own diagnostics for about a $10 investment (newer laptops with USB ports need a more expensive cable, about $40). The Fiero has an ALDL port that uses OBD-I (after '95 cars went to OBD-II). This port allows us to hook up a computer using a home-brew cable and free software to see what the engine sensors are doing. If you have basic soldering skills (or willing to learn, its pretty easy) then you can make an ALDL cable with Radio Shack parts for cheap:
http://couleefiero.tripod.com/ALDL.htm The go to http://winaldl.joby.se/ and download the free software. If you don't want to make a cable then buy one from srat110 or others in the Mall section of the forum. Or go to http://www.aldlcables.com/ and get the USB version.
Heres the ALDL plug behind the cigarette lighter panel on jetman's car.

avengador1:

Thanks, the O2 sensor hasn't been replaced to my knowledge. I'll give that a try.

Hudini:

Thanks for the info. I don't have a laptop, but I have a friend that does. Unfortunatly all of his laptops are new and only have USB ports. I'll have to work on getting a USB ALDL cable.

Thanks again guys! "+'s" for both of you.

Anybody mention air filter ?

You might also add an extra pound or 2 of air to your tires - might give you a little better mpg but more tire wear down the road (and maybe a harder ride).

keep your A/C turned off when possible. You might also try a can of fuel injector cleaner.

I have an 88 Formula (auto trans) with 79k miles and get 20 to 22 normally; 91 octane fuel. The rating on the window sticker was 18 city / 24 highway.

[This message has been edited by PaulJK (edited 07-19-2007).]

PaulJK

Thanks for the ideas. I just changed my airfilter this week. And I check my tire pressure every Friday. I have 4 new ones so I've not had to add any air this month. My A/C doesn't work, so that's never an issue. I think I mentioned in my original post that I did the injector cleaner treatment.

Thanks for the original sticker info on MPG. I got mine used, so I've just been going by what kind of mileage I was getting when I purchased it two years ago vs what I'm getting now. A "+" for ya.

Allso check your tire pressure,low tire pressur will reduce your MPG.
A dirty air filter will allso reduce your MGP (starved for air).
A new fuel filter can help (fuel starved, if it's clogged with rust and debrie).
A fast Idle will cause poor gas milage.
Consolidateing your trips can save on gas.

Thanks.

I meant that you might "cheat" by over-inflating your tires a pound or 2 which might give you a little better mpg.

James Bond 007:

PaulJK brought up the tire issue, and the air filter one as well. (I adressed them in my reply post) Thanks for your help though. I changed my fuel filter the same day as my airfilter. My idle is actually pretty low (900 rpm). When it comes to trips, I only take the ones that are necessary. I'm normally having to drive my van anywhere else (wife, and three kids. )

A "+" for the help

PaukJK:

You're welcome

Ahh, I don't know why I didn't see that in your post...there it is plain as day. Hmm..I might try that for now until I can get an O2 sensor, but I don't want to put any undo wear on the tires for too long. Thanks.

[This message has been edited by Flying Pony (edited 07-19-2007).]