Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

- - - - -

2.5 L Engine rpm modulation


  • Please log in to reply
3 replies to this topic

#1 Guest_pelagic30_*

Guest_pelagic30_*
  • Guests

Posted 30 July 2003 - 04:23 AM

90 Legacy with 2.5 L, the book says the idle cannot be adjusted mechanically, so what sensor(s) do I start looking at. When sitting in neutral at idle, the engine rpm falls down to about 200-300 then the ECU realizes that the engine is running way too slow and kicks it up to 1000 rpm, then it falls back again, cycling up and down once per second. The car runs great otherwise and this is not really a problem (yet?) but I would like to fix this if it is a sign of future problems. The car has 83000 miles, as far as I know it has all the original engine parts / sensors.

Thanks

#2 Guest_rcoaster_*

Guest_rcoaster_*
  • Guests

Posted 30 July 2003 - 04:51 AM

It could be your Idle Air Control (IAC) valve, or a loose vaccuum hose somewhere. Check for vaccuum leaks. Also, there might be deposits on your throttle body as well, that might affect the idle speed.

BTW, how did you get a 1990 Legacy with a 2.5? I thought those didnt' come out in North America until 1995! You must mean the 2.2L.

-RCoaster

#3 Guest_Legacy777_*

Guest_Legacy777_*
  • Guests

Posted 30 July 2003 - 06:03 AM

You have a 2.2 liter in your 1990 legacy.

The IAC valve is most likely sticking. It is located below the PCV valve. There was a procedure around here some where on how to clean it. Anyway, the jist of it is, you need to remove the top electro magnet portion of the sensor. Before doing this, make sure you scribe the orientation of the top controller portion to the body, so you get it aligned exactly how it was before. With that off, try and move the IAC valve. It should move freely and be smooth. If it doesn't, remove the hose that connects to the intake arm that's connected to the IAC valve. Spray some brake cleaner in there and work the IAC valve back and forth until things are moving freely and smooth.

The above is assuming you have an AT. If you have a MT, they use a different valve, and from a buddy's experience trying to clean his....it didn't work to good.

oh yeah....do check for vacuum leaks as well before you tear into cleaning the IAC valve.

#4 Guest_pelagic30_*

Guest_pelagic30_*
  • Guests

Posted 30 July 2003 - 02:07 PM

Ok 2.2L, I was looking at the wrong VIN codes.

Thanks for the great advice ! I think a vacuum leak is a distict possibility as I noticed some mouse turds around the engine compartment.

I didn't think it was possible to be happier owning a Sooba Roo, but finding this forum certainly has.

Thanks again,

Keith

88 DL Wagon (same old 1.8L)
90 L AWD Wagon (now with 2.2L engine)
90 L 2WD Wagon (also now with 2.2L engine)




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users