Intermittent loss of power

[Evil02outback]

02 OBW ej25 single cam auto

This just started loosing power and it's not predictable at all.

Driving out of my road the car will loose power around 1/4 throttle going up hill medium load on the engine ,

I hooked up my scanner/system monitor and I was able to see what was going on and why I lost power.

But when it did my timing would go to 0 when most of the time idle is 15deg and running its around 30.

I'm kinda at a loss but am suspecting the TPS is staring to fail but it doesn't do it all the time so it is making it difficult to diagnose

[1 Lucky Texan]

could be knock sensor - cheap/easy to swap

 

sometimes a failing cat conv will clog the exhaust

[Evil02outback]

But wouldn't a clogged cat throw a 02 code

[dp213]

+1 on knock sensor

[dp213]

Also if the tps is going bad, that can give you power loss

[golucky66]

In my experience a flaky tps will set a check engine light because it's a safety concern. If the ecm is seeing different signals from your sensors on the pedal verse on the throttle body. It doesn't want the car to run away.

 

This is all assuming the car is drive by wire. Which i believe the outback in 02 were.

[Evil02outback]

No this one is cable

[montana tom]

Outbacks went full drive by wire in 2005 ,  calf. and other high emission state cars went DBW in 2004 or possibly sooner.  Haven't seen any 2002 DBW outbacks.

[golucky66]

Alright. Didn't know exactly when. Thanks.

[ferret]

In late 2001 and early 2002 there were a run of DEFECTIVE oxygen sensors. The Front Sensor that is. If yours is original, read on.

 

These fail AFTER the car warms up and is in CLOSED LOOP MODE.

 

When cold, vehicle runs fine. When it gets warm, it starts shutting the engine off like you have a blocked fuel filter or the fuel pump is shutting off.

The way to check this is either to have an OBDII scanner that can display LIVE DATA, and watch the FRONT Oxygen Sensor. 

If it all of a sudden goes RICH ( over 1v and stays there while the engine is stumbling ) , this SHUTS the injectors off and this is why the engine stumbles and seems to shut off.

Another way is WHEN it's acting up, shut off the engine, open the hood and down on the passenger side UNPLUG the front oxygen sensor.

THIS WILL SET A CHECK ENGINE code. puts the car in OPEN LOOP mode, and see if the cars can be driven WITHOUT the stumbling..

This is how we diagnosed quiet a few of these 10 plus years ago.

 

Just another thing to check IF you have an original front oxygen sensor.

Edited August 15, 2017 by ferret

[Evil02outback]

Swapped out the knock sensor it, night and day difference on how it drives, will keep updated if it is not resolved