New User! My 96 Legacy is lagging..Help!

[Blondie521]

Ok guys, it may sound weird for a girl to have done these things but i have changed my fuel filter, spark plugs, changed the oil, i have no vacuum leaks and my tires are to the right psi but my car is still sucking as far as power. i only got 153 miles in a full tank of gas. when i turn my ac on my car jumps, example: my ac was on i went to stop at the red light, it turned green before i stopped all the way so i pushed the gas and my car started dancing frontwards and jerking backwards. it only did it until i turned the ac off then it was fine. besides the treatments i put in the tank everyother time i fill up i dont know what else to do to get better gas mileage and more revive the power that it once had..... HELP!!!!

[crazy D]

if you figure out this problem, i hope my buddy brian see's this. his T leg is getting like 15 mpg:eek:

 

 

p.s......its damn sexy if a girl goes out and works on a car.

 

 

the subaru kid

-Dalton

[porcupine73]

Hi Blondie521 and welcome!

 

First thing I'd check in this case is the knock sensor. They liked to crack on that era and cause power loss and reduced economy without necessarily causing the check engine light to come on.

 

Another possible items is front o2 sensor replacement. These don't last forever, maybe 80k-100k miles is a good lifespan. It can cause reduced fuel economy as well.

 

There are many other things that can reduce fuel economy as well such as dragging brakes, etc.

[Blondie521]

thanks guys, believe it or not when i bought the car alittle over a year ago the guy told me that the o2 sensor was missing but it wasnt really necessary, what a jerk for lack of wanting to post more profound words!

[porcupine73]

hm...o2 sensor missing? You would get a check engine light for that. Unless he did some circuit to fake out the ECU. That would definitely impact fuel economy if it were the front o2 sensor.

 

If it was the rear o2 sensor he was talking about that is for emissions purposes only and would not impact fuel economy (except the reason it was removed might impact fuel economy).

 

If you get a front o2 sensor, OEM is highly suggested. Subaru's are also a little picky about plugs, they like NGK. And they like their own OEM plug wires.

[idosubaru]

is the check engine light on? if so you need to read those codes and start there. the knock sensors are problematic for this year, it's only one bolt to remove it, worth checking. the housings crack.

 

when is the last time the plugs and wires were changed? and are the Subaru wires and NGK plugs? if they aren't Subaru wires, it wouldn't be surprising if that was the problem. but you should have a cylinder misfire Check engine light if that's the case.

[jamal]

Definitely pull the codes and replace the o2 sensor if it's missing.

 

I had a bad knock sensor and the car would hesitate and stumble, and the CEL wasn't on.

[msmithmmx]

My knock sensor keeps tripping the "check engin light" I have now started to notice my normal 23MPG to to 18. My OBW is at 175K

[porcupine73]

Yah those knock sensors can be a doozy. It's the first thing to inspect for cracks (though it can be faulty without cracks too) as it is easy to do.

 

I had my knock sensor out, wrapped in bubble wrap, and grounded with an alligator clip. A few times when driving it threw a knock sensor code, probably when the clip didn't get a good connection. Man the second that would happen the vehicle nearly stalled out and had like zero power. And when the a/c compressor would turn on the engine would nearly die.

[2.5GL]

If you get a front o2 sensor, OEM is highly suggested. Subaru's are also a little picky about plugs, they like NGK. And they like their own OEM plug wires.

 

Ditto.

 

More in-depth: is this all the time, or intermittent?

Any mods to the intake/exhaust?

 

If it is all the time I would check to make sure the timing belt, more specifically, the timing relation between crank and cams is correct. With covers removed, all "marks" should point straight up and match the "notches" on the timing covers (cams) and the boss on the oil pump that holds the crank sensor (crank). If one of the cams is off a tooth it will upset everything, but still run.

 

If it is intermittent, such as while driving, or passing, I would add the possibility of an air flow meter being the problem.

 

If it is more frequent "off-the-line", or from a stop, I'd guess O2 sensor.

 

Either way, a knock sensor is a good idea as well.

 

Oh, and stop the fuel treatments, they could make it worse IMO, as gasoline is already a solvent (loosely defined, of course), and you never see anything built up where gas sprays...:-p plugged injectors are more of a filtering or mechanical failure issue.

 

Double check that your CHECK ENGINE light works with the key on, engine off, if not, you should be checking codes, and figuring out why the light isn't on. ECU could be bad... It happens, but not often... Only when somebody tries to "Jump start" and connects the cables to the wrong terminals.

 

 

Lewis