Bad gas mileage..

2000pontiac6 · 01-22-2006, 08:36 AM

I have a 2000 3.8L firebird with a catback and intake... My car has been getting no better then 17mpg for the longest time. 17 at best. I don't do much long distance driving but come on, my V8 friends are getting the same or better gas mileage. Should I take it somewhere to be checked out? Could my cat be clogged? What can I do to change this?

**bandit95** · 01-22-2006, 01:00 PM

is it an auto or m5? do you mainly do city or highway? my 96 v6 with an a4 usually got about 17 or 18 mpg between city and highway. but dont feel bad, the trans am i got now gets about 12mpg.

2000pontiac6 · 01-22-2006, 05:54 PM

Its an auto... I mainly just drive it to school and friends houses. I just don't understand how my friend with V8s get the same or better, even if they are mostly older years.. I can't believe the mpg the ls1 guys are saying they get.

quicky06 · 01-22-2006, 06:15 PM

welcome to the club of bad gas milage. i move up to 16mpg from 8 with my 88 blazer

**bandit95** · 01-23-2006, 06:32 PM

alot of it can also deal with the gears you got, if the car has the time to really warm up in the time it's driven, and you could check to see if anything needs a tune up, the tire pressure is good, and so on. the ls1's do accomplish some amazing gas mileage especially on 6 spds. even compared with the v6's. the gears on your car should either be a 3.08 or a 3.42 gear, depends on if you got the sports and performance package or not. unless it's running badly or smelling like a rotten egg your cat is ok. best of luck to ya.

'94 Camaro RS · 01-24-2006, 02:11 PM

if you think about it the v6 has to work harder to get the car moving unlike the v8. but you should still get more than 17 mpg. did you check the plugs,wires, tire pressure??

**PaganEgyptian** · 02-14-2006, 05:07 PM

Even with my Hopped up V-6 I got 32mpg running a constant 65-70mph for 450 miles on the highway, and around 16ish city. But then again, I do not have a cataluytic converter or EGR.
When have your plugs been changed last?????? I would do a tune up with new plugs, wires and filters (air and gas) something is not working efficently.... not much else computer-wise like EGR or such would cause that.
Go to your local Muffler shop and have them do a backpressure check on your catalytic converter. too much restriction will also kill yoru fuel mileage.Good Luck
-Tim

**NE98LS1** · 02-19-2006, 10:10 PM

wow, that sucks, i get around 24 with my 3.23s and a V8!

**supermando** · 03-17-2006, 07:21 PM

I used to get better than 20mpg with my 1994 firebird V6 with 3:42 gears and cold air intake. I have a 2002 WS6 now and it's true that with the extra HP the trans am's don't have to try very hard to get around. With my firebird I would constantly pass 3000 rpm with normal driving. Now with my WS6 I can get around with some pretty descent acceration and cruise the highway at upto 65mph without ever breaking 2000 rpm. I get the same mileage now as I did with my V6 firebird. About 22-25 mpg.

**m6speed** · 03-22-2006, 09:50 AM

check plugs and wires, cats, air filter, and your o2's

**TXMaro** · 03-23-2006, 05:39 PM

sucks.. I'm gettin 23 combined with 3.42s and exhaust - headers. Intake goes on this weekend. Like they said.. tune up.

**Raoul-Duke** · 03-25-2006, 09:51 AM

**Jeep41** · 04-10-2006, 02:58 PM

This one was to easy...

**iLIKEtransAMS** · 04-13-2006, 09:33 AM

damn man, I just figured out I get about 14 mpg in town. I drive a 95 3.4 firebird

**myk02k** · 04-19-2006, 11:19 PM

my Z went from 180 miles per fuel-up to 260 miles after a sea foam, fuel filter swap, 3000 mile drive, and new tranny. Though I don't recommend you driving 3000 miles and getting a new trans for gas mileage, I would check to make sure everything is well-fitted on the intake and its not leaking anywhere, swap out the fuel filter and sea foam it to try to clean up the fuel injectors. If that doesn't help then get it checked up on. You may have just bad injectors or spark plugs. If you had a clogged cat, I think that changes the exhaust tone.

**myk02k** · 04-19-2006, 11:21 PM

(I put the wrong post here, sorry)

**98bpmta** · 04-22-2006, 06:57 AM

two words............ fuel filter

2000pontiac6 · 04-22-2006, 04:20 PM

Originally Posted by myk02k

my Z went from 180 miles per fuel-up to 260 miles after a sea foam, fuel filter swap, 3000 mile drive, and new tranny. Though I don't recommend you driving 3000 miles and getting a new trans for gas mileage, I would check to make sure everything is well-fitted on the intake and its not leaking anywhere, swap out the fuel filter and sea foam it to try to clean up the fuel injectors. If that doesn't help then get it checked up on. You may have just bad injectors or spark plugs. If you had a clogged cat, I think that changes the exhaust tone.

Stupid question, whats the sea foam?

**myk02k** · 04-22-2006, 05:57 PM

You can purchase Sea Foam from autosports store. There's different direction as to where you can put it in your car (my bro put it in a brake booster vacuum, i think you can put it directly into the throttle body. It's suppose to be a type of treatment to clean out your fuel injectors, cylinders, block, and catalytic converter.

quicky06 · 04-24-2006, 06:35 PM

i went from 15 to 20 by switching to full synthetic(still on the first change) and plugs (platinum +4) i replaced my fuel filter about 5k ago at the most same with pcv. i need to get the radiator flushed and new shocks and struts, but what else can i do for gas milage besides not driving like an ass?