Power Mode comes on randomly

[turbocooker]

Hey guys I'm new here to Legacycentral and also a new subie owner. I recently picked up a '91 Legacy SS auto and I've been having some issues as of a few days ago. My car has started randomly going Power Mode on it's own while at cruising speeds. It does it in D and in 3rd, I noticed that if I put it in 3 and turn on Manual mode it doesn't do it anymore. It started having issues a couple days after my speedo stopped working. I figured the speedo has something to do with it so i fixed that and it didn't fix the Power Mode issue. I checked for codes and nothing came up. I've also swapped the TCU with my buddy's and that didn't change anything. I've searched the web and came up with nothing. I'm at a loss here, can you guys help me out?? Thanks in advance.

[turbocooker]

Ok today I got a cel. Got a code 42-idle switch fault. I don't know if that has anything to do with the shifting problem.

[turbocooker]

Ideas......anyone???

[ericem]

Replace the throttle position sensor so probably easier to get ahold of a whole throttle body.

[Florin1]

Bump for my buddie. He's a good guy boys so chime in! (I've been telling him about how great our cars are and and finally got him into one, and now its frustrating him.) Dang in there D. someone will chime in, this site isn't as busy. Let it stew.

[Florin1]

http://www.surrealmirage.com/subaru/trans.html

[ericem]

Didn't i just reply?!!

The TPS is the idle switch!

[turbocooker]

Didn't i just reply?!!

The TPS is the idle switch!

How can I check the TPS. What voltages should I be seeing at WOT and with the TB closed.

[Florin1]

http://www.surrealmirage.com/subaru/engine.html Check halfway down the page under all the codes...

[turbocooker]

So I've been driving the car and the problem seems to have fixed itself. The only thing I did was unplug the TPS wires to check voltage. I decided not to check voltage cuz it was raining and I just plugged it right back in and shut the hood. So I dunno if that did it or the computer decided to no tweek out anymore. Untill it starts acting up again I'm gonna leave it alone. Thanks for the input guys.

[Legacy777]

Check the TPS using this procedure for the idle switch. There may be other issues, but you can at least check the idle switch part of the TPS. I'd suggest resetting the ECU/TCU so if the light comes back on, you can ensure that any previous codes are not there.

http://www.main.experiencetherave.com/s ... sting3.jpg

The other pages on testing the TPS

http://www.main.experiencetherave.com/s ... sting1.jpg
http://www.main.experiencetherave.com/s ... sting2.jpg