I have a 99 legacy outback that has got me stumped! Everything is best with a little background, so here is mine. I have owned the car for 2.5 years and have put on about 20k miles (currently at about 134,000). There have been no major repairs that I know of, and the timing belt was replaced 10 months ago. I have had no serious issues up until.....The car was driven by a friend 200 miles, then parked in his driveway. The parking lights were left on, killing the battery. Two weeks later I came to pick up the car, and discovered the battery. I charged it back up, then went to start the car. It idled very low and rough, requiring a little throttle to remain on. When I attempted to bring the throttle up, it would reach 1000-1200 RPM, then immediately drop to 300. There is a bunch of smoke, that seems to smell a little odd, but that might just be my nose.

 

There is no CEL on. I changed the plugs, plug wires, and fuel filter. I did not have a pressure gauge for the fuel line, but fuel squirted right out when I turned the engine over. I cleaned the PCV and checked all the fuses. There is no obstruction in the air filter.

 

At this point I am stumped. A CEL sure would be nice! Anyone have an idea, or experienced this?

Is there a banana in the tail pipe? How about the air filter box? Is it full is acorns or "fluff" from a mouse nest?

I inspected the air intake system all the way to the throttle body and didn't see any evidence of mice.I looked down the exhaust pipe, and didn't see anything. (Particularly no bananas)

IAC hose not connected?  Pcv hose not connected?

Possabilitis, timing belt jumped, clogged exhaust system, clogged cat. Unbolt the exhaust from the heads and see if the engine will rev.

Reset the ECU, (unhook the battery negative for 10 minutes) and restart the engine but don't use the throttle to keep it idling. If it stalls just restart it and allow the ECU to learn to keep the engine running. Using throttle to hold idle speed up keeps the ECU from learning the parameters it needs to maintain on its own and can alter fuel mapping for part throttle running.

 

Clogged cat is also a possibility but seems odd for it to clog while sitting unless it was overheated just before being parked.

Well, everything is fixed! It turns out that the ECU just needed to be reset. Too bad I wasted 2 afternoons fiddling with the darn thing! Thanks for the help guys.

 

 

-Cheers