# Surging idle in Subaru legacy

**URL:** <https://community.cartalk.com/t/surging-idle-in-subaru-legacy/3921>\
**Category:** Maintenance/Repairs\
**Created:** [August 30, 2007, 10:48pm UTC](https://community.cartalk.com/t/surging-idle-in-subaru-legacy/3921 "2007-08-30T22:48:57Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![fender](https://avatars.discourse-cdn.com/v4/letter/f/848f3c/32.png) [@fender](https://community.cartalk.com/u/fender)\
**Post date:** [August 30, 2007, 10:48pm UTC](https://community.cartalk.com/t/surging-idle-in-subaru-legacy/3921/1 "2007-08-30T22:48:57Z")

</div>

I have a 99 legacy, When I start it when the engine is cold, the engine revs up to around 3000 rpms for about five seconds. When the car warms up a little the engine will rev up a little and then drop down, rev up a little then drop down, I believe it is called loping. When it is doing this surging it is only changing a few hundred rpms.  
  
 Is this a vacuum leak? I cannot find the Egr valve to test it and the pcv valve clicks. Any suggestions?

---

<div class="post-metadata">

**Author:** ![Beadsandbeads](https://avatars.discourse-cdn.com/v4/letter/b/c57346/32.png) [@Beadsandbeads](https://community.cartalk.com/u/Beadsandbeads)\
**Post date:** [August 31, 2007, 12:12am UTC](https://community.cartalk.com/t/surging-idle-in-subaru-legacy/3921/2 "2007-08-31T00:12:16Z")

</div>

It may be, indeed, a vacuum leak. A good way to find them is to wave an unlit propane torch around close to the places a leak might be occuring.

---

<div class="post-metadata">

**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\
**Post date:** [August 31, 2007, 12:20am UTC](https://community.cartalk.com/t/surging-idle-in-subaru-legacy/3921/3 "2007-08-31T00:20:27Z")

</div>

Yes it could be a vacuum leak.( You may also use soapy water to detect a leak)

Perhaps one or more of these too:

A fault in the fuel or ignition systems  
A plugged PCV valve or hose (if it rattles it’s good)  
Air filter clogged  
Leaking head gasket (compression check)  
Camshaft lobes worn.

---

<div class="post-metadata">

**Author:** ![fender](https://avatars.discourse-cdn.com/v4/letter/f/848f3c/32.png) [@fender](https://community.cartalk.com/u/fender)\
**Post date:** [August 31, 2007, 8:38pm UTC](https://community.cartalk.com/t/surging-idle-in-subaru-legacy/3921/4 "2007-08-31T20:38:20Z")

</div>

Thank you for your suggestions. I will work on it this weekend and let you all know how it works out. Thanks again.