# Pulsing RPM

**URL:** <https://community.cartalk.com/t/pulsing-rpm/28738>\
**Category:** Maintenance/Repairs\
**Tags:** rpm, start\
**Created:** [April 4, 2009, 7:40pm UTC](https://community.cartalk.com/t/pulsing-rpm/28738 "2009-04-04T19:40:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![henrye](https://avatars.discourse-cdn.com/v4/letter/h/c37758/32.png) [@henrye](https://community.cartalk.com/u/henrye)\
**Post date:** [April 4, 2009, 7:40pm UTC](https://community.cartalk.com/t/pulsing-rpm/28738/1 "2009-04-04T19:40:52Z")

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I went out to start my 2006 Chrysler Pacifica (48000 miles)on a very rainy day and it didn’t want to run. I tried pumping accelerator as it tried to die and I won out. I drove it several miles and then went in store for an hour came out and had a replay of not wanting to start and getting it going. Drove home and parked for a day. It starts fine but at 3000 RPM it runs up and down or what I would call a pulsing action. No check engine light. Any ideas ?

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**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\
**Post date:** [April 5, 2009, 2:45am UTC](https://community.cartalk.com/t/pulsing-rpm/28738/2 "2009-04-05T02:45:46Z")

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Possible vacuum leak, a faulty IAC (Idle Air Control) valve and/or a dirty throttle body.

Another one could be a loose or broken TPS (throttle Position Sensor).