I just bought this car. Everything is ok except the gas milage. 87 TurboII

Its got:

90 jap spec motor.
HKS mushroom filter
Home made blow off valve
2.5 exhaust (small leak at y pipe) no cats
It runs pre mix
EVERYTHING else is stock.

It doesnt leak gas. I just put NEW plugs in. It has a fresh oil change too.

The temp is pritty cold here(10 degrees F), and Im driving normal (no racing or heavy foot)

What should I do?

 

I think that usually poor gas mileage is attributed to a bad O2 sensor.

 

Yes, but not "this" bad. Time for a full tune up.

Steve

 

I think I'd check your maths before you check the car. With fuel consumption that high you'd definitely be seeing and smelling the results of excessively rich mixtures. The car would be running very poorly.

Just in case you were doing it wrong, fill it up, zero the odometer, drive it until near empty, fill it up again, and divide the mileage by the amount of fuel from the second fill.

 

As NZ mentioned, at 7MPG, the car would bearly run. Black smoke would trail out of the exhausts, and I doubt you would see anything close to an idle...But a full tuneup certainly wouldn't hurt.

 

I devided the miles by gallons. The car went 100miles on a FULL 14 Gallon tank. (7MPG) On the highway it got 120 Miles on a FULL 14Gallon tank. Sometimes It smells like gas form the exhaust. It floods VERY easily.

What is considered "normal" mileage on a turbo II?
Whats in a full tune up?

Thanks, Mike.

 

You have to measure the fuel used using the method I described above, or you'll be way off. If you did, and you really did consume 14 gallons of fuel, then either your odometer is way off or you have a fuel leak. There's just no way the engine's burning a gallon every seven miles of normal driving.
They all do. Do you see any black smoke? With that mileage you'd be making clouds of it.
I get ~17mpg with daily use. 7mpg would be what I'd expect from a track session.

 

get rid of the HKS air filter and put something on that will actually flow and clean the air

 

on my 87 TII when i had it, it was stock besides a K&N filter and a 2.5" bonez dp and 2.5' bonez high flow cat, with some higher flowing mufflers.... it got 30 mpg on the way down to TX at 80 mph, and 27 mpg at 75 mph.... my 88 TII now with too many mods to list gets 22 mpg at 80 and 21 mpg at 75.... gets about 12-15 in the city

 

im running without o2 sensor(cant find the wire) and i still manage to get 15 in the city...recently i been keeping it revvin at 1.5k while stopped....i get better milage...tell me this is a good thing

 

On the second fill you leave the odometer? Then the mileage will be alot higher. (two tanks of gas)

I fugured you devide your milage by one tank.

 

I think you've misunderstood. The amount of the first fill is irrelevant, as long as the tank is completely full and the odometer is zeroed. When you next refill (it must be completely full again), the amount you put in is the amount consumed while driving the distance measured on the odometer. Those are the figures you use to calculate mpg. Your problem is not the car; it's your calculation method.

 

damn 7mpg thats seriously bad

check the A/F ratio

 

i got like close to that when i blew a seal on the rear rotor and had to drive the car back home 165 miles on half a motor at 80 miles per hour not bad id say But needless to say the car is now sitting wiating for a rebiuld

 

my 20b has never dipped below 9, and thats when it wasn't running so good. it gets 18now, it used to get 18 with the 2 rotor....

 

my 20b has never dipped below 9, and thats when it wasn't running so good. it gets 18now, it used to get 18 with the 2 rotor....

 

I got very good gas mileage with mine when I drove her back from Michigan to Ohio. I made about 200 miles with 3/5 full tank of gas before the light came on. I just did like three WOT pulls when I got on the highway from rest stops and was just cruing in 5th gear at 65-80mph all the time. Something is definately wrong with your car...

 

Ok, just to pipe in here, at one point on one of my former engines, I was getting around 6MPG (and, yes my gauge was working correctly at this time), my engine also **** an apex seal a couple of months later, so take it for what its worth. Now, I have my new rebuild engine in my car, and I thought I was getting horrible gas mileage, however, after I stopped to fill my car up, I was only able to get 11 gallons into the fuel tank, the s4 gas tanks are 16.6 gallons, so in fact it is my gauge that is off.

Make sure that you really know how much gas you put into your car and how many miles you got out of a full tank.

 

yea, the gas tank on my car is 16 gallons. Er, 16.6, whatever. Your gauge must be off, but you should still be getting better gas mileage I would think.

 

well..if you are dividing milage driven by gallon of gas used....doesnt matter if the tank is completely empty or partially empty......do a fill up, reset meter.....drive around for a while....when its 1/2 or 3/4 full(....yes..the tank is 1/2 full....not empty) fill up again...check out the # of gallons pumped on the pump meter and divid that by your milage....

 

you mean devid the miles by the gallons?