I posted something similar a while ago but no one responded, so i'll try again. I've got a 95 Impreza L coupe with the EJ18 and a 5-speed. It's got 72000 miles on it. For a couple months now it's been getting about 25 mpg when it should get more. I think it has something to do with the hesitation when I start it. It is also idleing REALLY low, right above the 0RPM mark. I'm a broke college student so I'd prefer to diagnose this and fix it myself. Please hellp me figure out what the deal is.

 

IAC Valve
Spark plugs
Plug wires
TPS sensor

I take it you're not getting a CEL? Try re-setting the computer. Unhook the negative terminal on the battery, hold down the brake pedal for 15 seconds, and then let it sit for about 30-60 minutes. There are a couple of ways to re-set your computer, but this is what I usually do.

-Charles-

 

Just to add to what I mentioned earlier, have you replaced the air filter and fuel filter recently, or ever? I always thought 25 mpg was good for any Subaru, even the 1.8 liter. There are so many things that can affect gas mileage:

oxygen sensor
air filter
fuel filter
spark plug
spark plug wires
clogged catalytic converter
exhaust leaks
MAF or MAP sensor

Things that can cause hesitation:

IAC (Idle Air Control Solenoid Valve)
Plugs and wires
Crank and Cam position sensors
Fuel Pump and/or Fuel Pump relay

Check the basics like plug wires and filters and maybe it will be something simple.

-Charles-

 

I replaced the pcv valve, spark plugs, fuel filter, air filter and oil/filter within the last 4K miles. Today I went to a local subaru specialty shop in denver west called Mobile Mechanics inc. I'm gonna take it over there for them to diagnose it. I'm hoping they can just plug in a code reader and find the problem but i got a feeling it'll be more involved than that.

 

oh yeah, i'm not getting the CEL

 

If you're not throwing a CEL a code reader won't do you any good. My TPS sensor wasn't throwing a code, but it had a dead spot. Against everything everyone told me, I took it off, messed with it for a few minutes, re-set the computer, and all has been well. Just luck I guess. Did you try re-setting the computer? Hopefully you can get it fixed without doing too much harm to the bank account.

-Charles-

 

I had the same problem with my 1995 L w/1.8. A twenty dollar set of plug wires fixed it right up.