# 1999 Subaru Impreza Outback Sport - "Chatter When Acclerated" **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [August 18, 2019, 11:12pm UTC](https://community.cartalk.com/t/1999-subaru-impreza-outback-sport-chatter-when-acclerated/146997 "2019-08-18T23:12:24Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![LisaBowles](https://avatars.discourse-cdn.com/v4/letter/l/2bfe46/32.png) [@LisaBowles](https://community.cartalk.com/u/LisaBowles)\ **Post date:** [August 18, 2019, 11:12pm UTC](https://community.cartalk.com/t/1999-subaru-impreza-outback-sport-chatter-when-acclerated/146997/1 "2019-08-18T23:12:24Z")
Has a chatter when accelerated. Sounds like a pencil stuck into a boxed fan. Comes from center engine. Loses power uphill. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [August 18, 2019, 11:58pm UTC](https://community.cartalk.com/t/1999-subaru-impreza-outback-sport-chatter-when-acclerated/146997/2 "2019-08-18T23:58:06Z")
Is the check engine light on? How many miles on this Subie? Does the chatter get faster as the car goes faster? Or when the engine turns faster when y rev it up while in Park? ---
**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\ **Post date:** [August 19, 2019, 1:23pm UTC](https://community.cartalk.com/t/1999-subaru-impreza-outback-sport-chatter-when-acclerated/146997/3 "2019-08-19T13:23:17Z")
Is the OP familiar with what _spark knock_ sounds like? Also called “detonation” or “pinging”, this is usually described as sounding like **pebbles being shaken in a tin can** , and it typically takes place when climbing hills and when accelerating. If that is what it sounds like, then I think that your “chatter” is likely to be a case of spark knock. This can be caused by a variety of problems, including but not limited to… _Spark plugs in need of replacement_ _An engine that is running too hot_ _A malfunctioning EGR system_ _Cylinders that have a lot of carbon build-up_ Years ago, ignition timing that was advanced too far was also a major cause of spark knock, but I don’t think that your engine’s timing is adjustable. Because spark knock can destroy the engine’s valves and can even damage the tops of the pistons, this is something that should be remedied a.s.a.p. I recommend a trip to a qualified mechanic’s shop for diagnosis and repair. 🤔 ---
**Author:** ![shanonia](https://avatars.discourse-cdn.com/v4/letter/s/9de053/32.png) [@shanonia](https://community.cartalk.com/u/shanonia)\ **Post date:** [August 19, 2019, 5:55pm UTC](https://community.cartalk.com/t/1999-subaru-impreza-outback-sport-chatter-when-acclerated/146997/4 "2019-08-19T17:55:08Z")
Manual trans? Does using a lower gear help? Automatic trans - does it downshift when you mash the accelerator pedal, as it should?