94 pa ultra horrible gas mileage help!! 8mpg

[97wagonlx]

my last tank got 8mpg god help i love this car but cannot afford that with a 50 mile round trip for work, i gave a tune up new plugs and wires doesnt seem much better probley 10 mpg at best what else can i do? it also has a new air filter as well, also feels kind of sluggish when i get on it it feels about on par with my 93 century...so...i dont think that is normal also will not leave any rubber like others claim it is supposed to

[rhandwor]

I would check the timing and the air pressure in the tires. Check for abnormal tire wear. Make sure it is running at the proper temperature. The computer needs the temperature to change from open loop to closed loop.

[97wagonlx]

Originally Posted by rhandwor

I would check the timing and the air pressure in the tires. Check for abnormal tire wear. Make sure it is running at the proper temperature. The computer needs the temperature to change from open loop to closed loop.

well im not sure on what the proper temp would be but it runs right around 195 to 200 i will check out the tires but i am not sure how to check the timing

[rhandwor]

Your temp sounds fine I had a customer years ago and the engine had a bad thermostat. The mileage doubled with a new thermostat.

[HotZ28]

Well, obviously you have more of a problem than a low air pressure in the tires! More than likely, your short term (STFT) and long term fuel trim (LTFT) count is way high. This can be caused by several things. It would be best to have it scanned and monitor sensors while the engine is warm. Your 02 sensor controls fuel trim and when it get's lazy, it is slow to respond to rich/lean conditions.

Basically, an oxygen (O2) sensor measures the amount of oxygen in the exhaust system to determine if the engine needs more or less fuel. When the 02 sensor is functioning properly, the ECM will control the fuel curve using the feedback from the 02 sensor.

When the 02 sensor drops to around 300mv, the ECM commands the fuel system to “go rich”. When the 02 output reaches 600mv, the ECM commands the fuel system to “go lean”. If you observed this function on a scanner, you should see a rapid flash back & forth, between rich and lean. O2 "counts" is how many jumps back and forth it makes.

Since 14.7 AFR is where it is most accurate and it is required to operate in such a narrow range, it is almost impossible to hold it there. When the ECM is using the O2 sensor to correct the fuel tables it measures how long it is lean and how long it is rich, if they are equal, then the AFR is at 14.7, right where it should be. If an engine operates “rich” for an extended period of time, it will kill the converter. A clogged converter results in power loss and poor fuel economy!

[97wagonlx]

Originally Posted by HotZ28

Well, obviously you have more of a problem than a low air pressure in the tires! More than likely, your short term (STFT) and long term fuel trim (LTFT) count is way high. This can be caused by several things. It would be best to have it scanned and monitor sensors while the engine is warm. Your 02 sensor controls fuel trim and when it get's lazy, it is slow to respond to rich/lean conditions.

Basically, an oxygen (O2) sensor measures the amount of oxygen in the exhaust system to determine if the engine needs more or less fuel. When the 02 sensor is functioning properly, the ECM will control the fuel curve using the feedback from the 02 sensor.

When the 02 sensor drops to around 300mv, the ECM commands the fuel system to “go rich”. When the 02 output reaches 600mv, the ECM commands the fuel system to “go lean”. If you observed this function on a scanner, you should see a rapid flash back & forth, between rich and lean. O2 "counts" is how many jumps back and forth it makes.

Since 14.7 AFR is where it is most accurate and it is required to operate in such a narrow range, it is almost impossible to hold it there. When the ECM is using the O2 sensor to correct the fuel tables it measures how long it is lean and how long it is rich, if they are equal, then the AFR is at 14.7, right where it should be. If an engine operates “rich” for an extended period of time, it will kill the converter. A clogged converter results in power loss and poor fuel economy!

ok well i will see about changing out the 02 sensor as well

[Mickey#1]

Before you change the o2 sensor make sure no spark plug wires are touching or close to the sensor.

[rhandwor]

Check closely for a crack in the manifold next to the sensor.

[Loekee75]

You said the car is sluggish as well as having bad mileage...have you changed the fuel filter?

[97wagonlx]

Originally Posted by Loekee75

You said the car is sluggish as well as having bad mileage...have you changed the fuel filter?

i havent changed the fuel filter yet either i just got this car so i dont really know it yet all i did was change the plugs and wires and put a battery in it

[Raul10141964]

check for bad ignition coil