Hello all,

With the price of fuel so high, I began to notice that my weekend car use so much fuel I think I have a problem.

My car is a 1988 Pontiac Trans Am GTA, 118 500 original miles, 305 TPI, 4 speeds automatic transmission, 3.27 rear and about every options except leather and the 350 TPI... I don't have one single modification on the car (not even a performance air filter).

With a full tank of fuel I did near 150 miles and it's about to be empty now! I don't drive the car hard at all. Maybe I got on it about 4-5 times but not for very long, the rest of the time I was going to the speed limit without accelerating hard. Let's say I did about 70% city and 30% highway...

Is something wrong? I changed this this year: cap/rotor/spark plugs wires/spark plugs (changed last year with ACDelco ones so they were still good probably), air filter and fuel filter and some more stuff that doesn't relate with fuel economy...

Where should I look? Can I do some things that don't cost too much and will improve my fuel economy.

The car doesn't seem to bog at all... I did a 15.56 on the 1/4 so should be pretty much alright for a stock 305 TPI GTA right?

Thanks a lot!

 

I think there's nothing wrong with your car, those figures are about the same for my '88 350 TPI !!
One exception, fuel is about $5- $6 a gallon overhere.........

(how's your tire pressure? a little higher won't hurt comfort, but will save some fuel!)

 

They are at 30 PSI... But the difference is that I have a 305 TPI, not 350 TPI... Should be more fuel economical no? Any one else can shime in?

 

Here it's 1.044$ the liter... Don't know how much it do the gallon but it should be pretty high

 

I've got a hunch...the horribly bad fuel sender.

When you say that you're doing like 150 on a full tank - how many gallons is that "full tank" worth? Most of our cars have about a 15 gallon fuel tank and I fill up at like 10 to 13 gallons with 210 to 230 miles on the odometer. Mine's an 87 350 GTA with 88 pulleys, so we should be neck and neck.

 

I don't know how many gallons, here in Canada we use liters so I'm not too familiar with gallons.

When I filled my tank I was near the empty mark... And did only 150 miles...

 

I usually fill my tank up with 10 gallons and get 200-225 miles out of it.

 

GEt an new O2 Sensor. When these thing go, they make your car run rich. The O2 Sensor should be change about every 30,000 miles.

 

How much do they cost?

Should I get an ACDelco one or any brand is fine?

I don't have a catalyctic converter anymore, can it affect anything?

 

Run a bottle of fuel system/injector cleaner through the tank. Make sure your tire pressure is good.

 

Oh I forgot to say I have put a bottle of fuel system cleanerr by Gunk. Cost me 10$ for the bottle and I heard it's pretty good.

 

well how many liters do you use? Good ol' internet shall convert it for me!

 

1 gallon is about 3,6 liter, correct me if I'm wrong.
Stick to the original AC Delco O2 sensor, I've heard bad things from other brands.
As for the injector cleaner, GM 's own cleaner should be one of the best!
Part #: 12345515, "Fuel System Treatment"

Oh, and in liters, we pay about $2 for a liter fuel........

 

I was getting like 11mpg (~150mi/tank) with my 350 tpi camaro. I installed the innovate motorsports wideband O2 kit ($212 shipped) and it now gets 15mpg (~190mi/tank). With gas at $2.60/gal in MD (0.65/liter) it should pay for itself.

 

So you guys think the next thing I should do is replace the O2 sensor with an ACDelco one? How much does it cost apporximately?

I heard putting a bottle of fuel system cleaner too often is not good. It could make the injectors leak, is it true? 'Cause I have put one like from Gunk like 1000km ago only so I think I should not put one of GM cleaner right away right?

Is the fact not having a catalyctic converter could affect my mileage?

 

Not having a cat will not harm fuel/ milage.
I don't think adding GM's fuel treatment right now will do any harm, it will get rid of whatever has left behind from the other cleaner....!!
The AC O2 sensor is not expensive at all, but i can't give you an excact price, cause I'm in Europe, different markets, different prices, just call a GM dealer to find out!
In the meantime, soak the excisting O2 sensor with WD-40 or something, and buy an O2 sensor socket to get it out!

 

thats about 9.4 mpg. thats not good. TPI cars should get around 16-18mpg daily driving

 

If the oxygen sensor is bad, will it show a Service Engine Soon light? 'Cause I have no codes at all...

 

yo when i first bought my car like 6 months a go i was gettin 9-10 miles to the gallon driving pretty nice. took it to the mechanic and my fpr was shot, needed a new computer and prom, and i had a leaky fuel injector, now im gettin like 13-14 mpg and i think with a new 02 sensor ill be up to 16-17

 

I have my 305 tpi.
You cant give one reason with no information for bad gas mileage. A o2 sensor probably will help, however how do we know the differce, I had all sorts of problems, bad knock sensor connector, bad injectors, bad sensors (in process of replaceing all), vacuum leaks, bad fuel filter, bad fuel pump, air filter, fuel cleaner isn't a good fix go to a shop and have them flush your intake. Mine poored all sorts of black crap out of the engine. Bad egr, Weak cams they wont give you servie engine codes but, but you will notice terrible gas mileage, terrible acceleration, and wont rev up quick. The list just keep going on. all sorts of reasons, even all city I can tell a big difference between city and high way. COMPLETE TUNE_UP

 

No.

 

I will try an oxygen sensor for now, I will try more after if it didn't helped... My car seem to rev fine tought when I give it gas. Just when I just started it sometimes it don't take it like it should.