whiteturbo87

So I have a 1988 camaro that I just started daily driving.It sure seems like it gets terrible gas milage.Info on the car is:1988 camaro,has 89 L98, T-5(was originally automatic),3.23 gears,has a piggy back chip with 89 cold start sequence,brand new fuel injectors from southbay injectors,new cap,rotor,plugs and wires.Car is all stock with brand new exhaust and cat.Still has air pump,egr and canister.Car runs great and RPM's are around 1900-2100 at 75-80.
I filled the tank a few days ago and have driven about 140 miles and am below half a tank.Most of those miles are highway driven.So im estimating about 14mpg.I question the gas milage because I get better mpg from my built 2001 trans am.Its a 6 speed but with 3.73 gears so the rpm's are the same.Is gas mileage that bad in TPI cars?Could it have anything to do with running 5 speed with the automatic computer?Or am i just reaching?Scan tool confirms closed loop operation,coolant temps in the 180's and oxygen sensor functioning properly.Anything else I should look at?

Sean O'Hara

If it seems like it gets terrible mileage, that is because It does. It's a Camaro. My 1988 GTA gets roughly 350 km to a tank and It is bone stock with an automatic. So if you are getting 140 miles to half a tank then I think you are getting pretty much the normal fuel economy or even better!

whiteturbo87

Well if thats the case then that sucks.And I guess i'll have to deal with it or swap in an LS1/6 speed some time.Oh and by the way,the gas guage AND factory tach suck in these cars

Sean O'Hara

The tach might be a little weird after your tranny swap, but the fuel gauge certainly sucks...I can lose a quarter tank of gas by being on a hill.

Johnny Blaze

iTrader: (15)

Run through several tanks, keep track of milage and calculate an accuratte MPG.

What about basic state of tune? Plugs, timing etc...

Driving style will affect it a lot. Getting into 5th as soon as reasonably possible helps, keep rpms down.


With a stock tire 2.23 and t-5 your RPM should be closer to 2500 at 75 mph. Slow down, or get 2.73 gears.

whiteturbo87

Plugs,wires,cap and rotor brand new.Timing is set at 6 degrees base.I dont have 2.23 gears i have factory 3.23 gears as this was an original automatic car.And i confirmed speed and rpm with scan tool.So thats what the computer is seeing.As for driving style,I drive it very easy and get it into 5th asap.I will run a few tanks of gas through it and get a good average though

Johnny Blaze

iTrader: (15)

Sorry, I misprinted, yes with 3.23 rear gears, a t-5 and stock tires your rpm should be about 2500 at 75 mph.

Whats the speed limit where you live? Slow down, that will help a lot too.

Maybe bump up the timing? Whats your plugs gapped at? 180 is too cold. What t stat you running. Get the temps up to 200 would probably help some.

Whats the exhaust? Stock? Do you have headers? What about this intake side? Gutted air boxes? K&N filters? They always helped my cars.

Johnny Blaze

iTrader: (15)

75 mph with a t-5 and 3.23 gears, assuming you have a stock 26" tire would be 2400rpms
80mph with the same would be 2600 rpms.

If you are only seeing 2000 rpms something is wrong.

Even a 2.73 rear would turn about 2200 rpm at 80mph.