BAD gas mileage!!!

[ricecart]

Hello everyone. I have a 200 daewaoo lanos and its been getting horrible gas mileage since i bought it. I fixed any vacuum hoses that i thought would be the cause but its still just as bad. I have already done basic maintanence on it such as; Air filter, oil change, spark plugs, suspension. There are no CEL or anything. I was looking at the PID data though and it was saying that the MAP sensor was reading about 1.5inHg. That seems a little high for me when the car is at idle. Does anyone have any specs that I can go off of to try and remedy my MPG issue? OR do any of you have an idea what may be causing it also? TIA

-John

[Daniel]

What is your "horrible gas mileage" in MPG or L/100km?

[daewoomofo]

when my mileage dropped out of nowhere it was bad spark plug wires. they looked ok, no CEL but my mileage dropped like 5 mpg out of nowhere. changed tu plug wires and it went back up. hope this helps, good luck

[ricecart]

Im not sure of the exact numbers on the MPG but it seems as though it would drop at least 1/8 of a tank on a 2-3 mile drive.

[Daniel]

Im not sure of the exact numbers on the MPG but it seems as though it would drop at least 1/8 of a tank on a 2-3 mile drive.

Let's take 50L for fuel tank capacity.
1/8 of that gives 6.25L( 1.65 US gallon).
If I'm right for 4.8km (3miles) that is...130L/100km or 1.8MPG

How to evaluate gas milage?
-Fill tank to the neck. Note mileage.
-Drive until approx half-empty.
-Refill tank to the neck. Note fuel volume and mileage.
-Calculate gas mileage.

Daniel

[Rodd1s]

Im not sure of the exact numbers on the MPG but it seems as though it would drop at least 1/8 of a tank on a 2-3 mile drive.

i can make mine drop 1/4 tank going round a long left-hand bend, or driving up a steep hill. its normal for the needle to move about a bit, but its a whole different story if (according to what you're saying) you get around 15 miles out of a full tank, which seems impossible - unless you have a 1000 hp engine - in which case you should fit a larger fuel tank.

on a serious note, it all depends on what driving you do mostly... i see anything between 200 and 300 miles out of a full tank (350 at a push), depending on whether i do alot of motorway (highway/freeway) driving for the most part of that tank, or if im gonna be sitting in bumper-to-bumper traffic for several hours for 6 days out of the 7 in a week. and even if you never sit in traffic, you can still use a lot (and i mean a lot) of fuel when driving thru town because you are constantly changing gears, changing engine load, speed, vehicle speed etc.

[MMamdouh]

forget about the fuel gauge

top up your fuel tank
drive for 100 Kms at 90KPH without flooring or A/C or extra passengers
top up your fuel tank again
divide 100 Kms over the amount of fuel used to top up tank in the second time
if the result is way less than 10kms/liter then you got problems

MMamdouh

[Puddle31]

I guess it's possible but that seems unlikely to actually be burning that much gas? Several others have explained how to get gas mileage. Fill the tank, run and measure mileage, refill the tank and do the math. I would check and make sure you don't have a leak somewhere? I would check under the car for a leak, especially if running and it only happens when the fuel system is under pressure. that's an awful lot of gas to go through for a few miles. Keep us posted.

[ricecart]

I will try to get the gas mileage next time i fill up. But what i really want to know is what the MAP should be reading at idle. My scan tool reads 1.52inHG at idle. Shouldnt it be around 20inHg?

[Daniel]

I will try to get the gas mileage next time i fill up. But what i really want to know is what the MAP should be reading at idle. My scan tool reads 1.52inHG at idle. Shouldnt it be around 20inHg?

I bet your scantool is giving you MAP (manifold absolute pressure) instead of vacuum.
1.52inHg seems quite a low pressure to me.

0 vacuum = atmospheric pressure =~ 29.53inHg.
100% vacuum = 0 pressure.

Try to wide open the throttle from idle and I think you'll see your reading increase.

http://www.international-auto.com/fiat- ... gauges.cfm .