I have an 08 Civic LX coupe with automatic transmission and 65K miles. About 6 months ago it started idling rough and kind of trembling/shaking on startup. When I backed out of the driveway and put it in D and gunned it up the street it would pretty much immediately go away. Replaced air filter and ran a fuel treatment through to no avail.

I took it to a mechanic and he said he didn't think there was anything wrong with it, said the computer was very sensitive and it would throw a check engine light if anything was wrong.

Since then the rough idle has gotten worse. Sometimes when I start it my keys even start shaking hanging from the ignition. And I have also noticed that quite often it seems to be revving higher than it used to before it shifts gears.

Any idea what might be going on?

 

try cleaning the IACV and throttle body.

 

Thanks for the advice. What are the chances this is an early sign of impending transmission failure? The revving/shifting thing is freaking me out.

 

well which is it rough surging idle or slipping transmission there is a big difference.

 

I don't know that I would call it slipping transmission but RPMs going higher before it shifts than it used to.