Gas Mileage
07-29-2012 | 11:39 PM
#1
Thread Starter
Staging Lane
Joined: Jun 2012
Posts: 62
Likes: 0
From: Vine Grove, Kentucky
Gas Mileage
I have a 1994 Pontiac Firebird Formula, 6-speed manual, 5.7L engine 119K miles. I recently bought this car three months ago and have finally gotten it road worthy. It had minor issues the previous owner didn't want to deal with, so he sold me the car for 400 dollars, the amount he would've got if he had junked it.
I have driven this car myself about 500 miles and on average I get about 14.5 miles to the gallon. I have almost replaced everything in the ignition system:
Spark plugs
Plug wires
Coil
Optispark
I have treated the gas with Techron once. It runs very well now but is there anything else I can do to improve gas mileage?
I have driven this car myself about 500 miles and on average I get about 14.5 miles to the gallon. I have almost replaced everything in the ignition system:
Spark plugs
Plug wires
Coil
Optispark
I have treated the gas with Techron once. It runs very well now but is there anything else I can do to improve gas mileage?
Last edited by idabomb00; 08-03-2012 at 11:23 AM.
07-30-2012 | 12:35 AM
#3
Should be a little higher then that. Im averaging 15mpg almost all city with a 6 speed, full bolt ons, heads/cam/intake.
Clean the maf, clean/replace the air filter. Id probably replace the o2 sensors also
Clean the maf, clean/replace the air filter. Id probably replace the o2 sensors also
07-30-2012 | 07:39 AM
#4
Does the car have any modifications? Does the exhaust smell like gas or have black smoke coming out of it? Do you drive with a heavy foot?
I average 14.5 mpg in mine. But on a recent road trip I did 23mpg on the highway.
I average 14.5 mpg in mine. But on a recent road trip I did 23mpg on the highway.
07-30-2012 | 06:01 PM
#6
Thread Starter
Staging Lane
Joined: Jun 2012
Posts: 62
Likes: 0
From: Vine Grove, Kentucky
I went easy on her for the test, it was a sunny and humid hot day. Most of the 500 miles I drove was on the free way, about 80 mph in sixth.
07-30-2012 | 08:38 PM
#7
You should be getting much better mileage than that with a manual trans. With bolt ons and mail order tune I got 24-27 mpg with the cruise set at 115 going across Montana.
Now with heads and cam, 9" rear with 411s I get 16-18 mpg driving a mixture of freeway and city and have gotten 24mpg in 6th gear cruising 70 to 75.
If everything ignition wise is working properly I would do a compression test, maybe you have a couple weak cylinders.
Now with heads and cam, 9" rear with 411s I get 16-18 mpg driving a mixture of freeway and city and have gotten 24mpg in 6th gear cruising 70 to 75.
If everything ignition wise is working properly I would do a compression test, maybe you have a couple weak cylinders.
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07-30-2012 | 09:00 PM
#8
Thread Starter
Staging Lane
Joined: Jun 2012
Posts: 62
Likes: 0
From: Vine Grove, Kentucky
You should be getting much better mileage than that with a manual trans. With bolt ons and mail order tune I got 24-27 mpg with the cruise set at 115 going across Montana.
Now with heads and cam, 9" rear with 411s I get 16-18 mpg driving a mixture of freeway and city and have gotten 24mpg in 6th gear cruising 70 to 75.
If everything ignition wise is working properly I would do a compression test, maybe you have a couple weak cylinders.
Now with heads and cam, 9" rear with 411s I get 16-18 mpg driving a mixture of freeway and city and have gotten 24mpg in 6th gear cruising 70 to 75.
If everything ignition wise is working properly I would do a compression test, maybe you have a couple weak cylinders.
08-01-2012 | 01:45 PM
#10
with the o2s they should be switching/jumping back and forth. the o2 that is staying constant is bad and needs to be replaced. Thats why you have split fuel trims. New o2 sensor and your good to go 
08-02-2012 | 12:05 AM
#12
Thread Starter
Staging Lane
Joined: Jun 2012
Posts: 62
Likes: 0
From: Vine Grove, Kentucky
I'm re-borrowing the scan tool I used. It's a snap-on mt2500, good tool.
Last edited by idabomb00; 08-03-2012 at 11:21 AM.
