Poor Mileage

corbanbrook · Post by **corbanbrook** » February 17th, 2006, 3:05 pm

Averaging out around 350 km/tank on my 92. Sure it has seen better days, but at around $40 to fill, im wondering what steps i can take to increase the mileage.

It has just had an oil change a month ago, and i replaced sparkplug wires, distributer cap + rotor. Whats next?

Tunes67 · Post by **Tunes67** » February 17th, 2006, 3:13 pm

Air filter and fuel injector cleaner in the gas for your next couple of tanks of gas. And sparkplugs if you havent already changed them when you put on the new plug wires.

Tunes67

Limegreen mx-3 · Post by **Limegreen mx-3** » February 17th, 2006, 9:18 pm

could be 02 sencer 20 bucks at a autozone

Yoda · Post by **Yoda** » February 18th, 2006, 10:45 pm

Do you have an exhaust leak? A pin hole leak in the exhaust before the cat can cause a big loss in mileage as well as power. I have the (8V) cousin to your engine. Just changing the O2 sensor to a 4 wire and repairing the exhaust leaks I drive an average of 90km/day. Before filling up Sunday night I would have to fill up again Thurday nights . Now I am only filling up on Sunday nights and some times I can stretch it out to Monday if I do more highway .

corbanbrook · Post by **corbanbrook** » February 18th, 2006, 11:09 pm

there is a heavy gasoline smell inside the car at times. i was thinking there could be a leak somewhere as well

Yoda · Post by **Yoda** » February 19th, 2006, 1:44 pm

Could be a pin holes in the gas tank usual around the seam. When the car is stopped the leak is so slow that the gas evaporates before it hits the ground. When the car is running the pump pressurizes the tank which sprays a mist of gas out the pin hole(s) . It still could be a bad O2 sensor and an exhaust leak if the engine were running rich enough.

Typhoonk · Post by **Typhoonk** » February 19th, 2006, 2:58 pm

hmmmm, I should get my exhaust leak fixed then..........

corbanbrook · Post by **corbanbrook** » February 19th, 2006, 3:11 pm

I think i will pick up a cheap 1 wire o2 sensor and see if that helps then. Could be the reason im getting fluctuating idles and engine flooding as well.

highlife · Post by **highlife** » February 20th, 2006, 1:28 pm

I just replaced the O2 sensor on my 93 1.6 sohc because it was getting 23 mpg. I did the voltage test on the old one before I took it out and it tested high indicating constantly rich signal. Checked mileage agian since putting the new one in and it is still 23 mpg. I dont smell gas at all but I have noticed since the mileage got so bad there is no more preasure release when I open the gas cap. Does yours do the same ?

corbanbrook · Post by **corbanbrook** » February 20th, 2006, 1:43 pm

highlife: I dont notice any preasure release when i open the cap.

Looks like im getting 17 mpg on this thing... assuming it has a 13 gallon tank.. but im guessing its probably a 10 gallon, i fill up when the low fuel light comes on, and only put in 35-40 litres. So if thats the case its more like 22 MPG around what you are getting.

Does your engine idle high? 1500-2000? in neutral?

highlife · Post by **highlife** » February 20th, 2006, 2:22 pm

Mine idles right around the recommended 750 rpm and smooth. I used to get 29 mpg (acceptable at 120,000 miles) then my timing belt slipped. I replaced the belt, double checking to insure I got it positioned correctly before putting the cover back on, then timed it at 10 btdc. Then I noticed bad mileage so tested the O2 sensor and replaced. Some where along the line the no pressure in the tank when removing the cap happened. I'm kind of at a loss other than to recheck the timing belt. It runs good just bad mpg. Mine is manual trans by the way.

Tunes67 · Post by **Tunes67** » February 20th, 2006, 3:49 pm

First thing to check if you arent getting a pressure release when you remove your gas cap is the gas cap itself. Try with a new cap and see if you get a vacuum pressure release after you run through at least 1/2 tank of gas. If you still get no vacuum release after that.. check your FPR. Also if you have a gas smell inside your car.. you may have a leaking seal around the lip of the sending unit thats mounted to the top of the tank under your backseat. A good indicator of a faulty seal is if the gas smell is particularily stronger right after you fill the tank. Fuel rushing into the tank bubbles alot and the fumes are pushed out of the tank by the incoming fuel.. so you would get a stronger fuel smell after fill up. A faulty seal would also prevent proper vacuum pressure in your fuel system. Hope this helps.

Tunes67

highlife · Post by **highlife** » February 20th, 2006, 4:21 pm

In my case the cap is new, when I got the car in April I noticed after driving there was gas smell at the cap so I replaced it and the tank did have normal pressure build up after that. Only noticed recently the pressure release was gone, no gas smell in or out though which got me thinking about the pinhole leak while driving comment. -- Sorry Corbanbrook, Dont mean to make this thread about my car I figure we both will benefit.

Danny · Post by **Danny** » February 20th, 2006, 7:18 pm

would a big ol hole in my cat be considered an exhaust leak?

Tunes67 · Post by **Tunes67** » February 20th, 2006, 7:23 pm

would a big ol hole in my cat be considered an exhaust leak?

Yeah.. that would qualify. And would definately effect your fuel economy.

Tunes67