# Rough Idle and hesitation

**URL:** <https://community.cartalk.com/t/rough-idle-and-hesitation/31388>\
**Category:** Maintenance/Repairs\
**Tags:** hesitation, rough, misfire\
**Created:** [June 3, 2009, 10:46pm UTC](https://community.cartalk.com/t/rough-idle-and-hesitation/31388 "2009-06-03T22:46:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![weekendwrench](https://avatars.discourse-cdn.com/v4/letter/w/ad7895/32.png) [@weekendwrench](https://community.cartalk.com/u/weekendwrench)\
**Post date:** [June 3, 2009, 10:46pm UTC](https://community.cartalk.com/t/rough-idle-and-hesitation/31388/1 "2009-06-03T22:46:40Z")

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I have a 2001 Subaru outback with 167,000 miles. Recently it has been running rough. I changed the fuel filter, changed the spark plugs and wires, changed the air filter, checked the vacuum which was normal and just changed the ignition coils. I can’t figure out why the car still idles rough at a light (usually)and most take offs have a hesitation. The car seems to run fine while traveling local roads and on the highway. The situation has been going on for a while. Gas milage through this has not suffered. What gives with the family chariot?  
  
 NEW INFO. The problem gets worse in humid/rainy weather and more so when the window defogger is activated. The check engine light came on throwing code P0302. What could be the solution to this conundrum?

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**Author:** ![Xebadaih](https://avatars.discourse-cdn.com/v4/letter/x/d07c76/32.png) [@Xebadaih](https://community.cartalk.com/u/Xebadaih)\
**Post date:** [June 3, 2009, 11:43pm UTC](https://community.cartalk.com/t/rough-idle-and-hesitation/31388/2 "2009-06-03T23:43:31Z")

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Why didn’t you just add your “NEW INFO” to your old post?

Another very possible cause is a problem with your cam position sensor. Also you should determine which cylinder is misfiring and check that injector for firing and leaking.

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**Author:** ![weekendwrench](https://avatars.discourse-cdn.com/v4/letter/w/ad7895/32.png) [@weekendwrench](https://community.cartalk.com/u/weekendwrench)\
**Post date:** [June 4, 2009, 2:30am UTC](https://community.cartalk.com/t/rough-idle-and-hesitation/31388/3 "2009-06-04T02:30:22Z")

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I have been having problems with microsoft script errors getting to the reply screen.  
Anyway. The misfiring cylinder is #2. Finding and checking sensors is not a problem. How do I test an injector for firing and leaking?