Q: Rough Idle in park and neutral runs smooth in gear

asked by on June 24, 2016

Earlier this year car started running rough.. took it to the dealership, who said the plugs were fine. Took for an oil change.. they changed oil, air filter topped the fluids.. and said 2 codes camshaft sensor, and P0456 small EVAP leak. we changed the camshaft sensor, car ran fine.. Until a couple weeks back it started idling and running rough.. I cant pull any codes.. dont have the money to take it to a mechanic.. troubleshooting as much as I can. Checked the gas cap... its not that. it starts.. it drives.. idles super rough.. smoothes out in gear. Ac works fine. not sure what else to look for.. no hissing under the hood..any suggestions? anything helps!!! Aloha

My car has 110000 miles.
My car has an automatic transmission.

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You will need to have the engine checked to see if you have codes to assist with diagnosis before looking at getting the ECM reprogrammed for the rough idle at a dealer. I would suggest having a certified technician diagnose the rough running to make sure it is not an engine vacuum leak or an ignition problem. If the Check Engine Light is on, you may have a problem that needs diagnosis or you will just need the ECM reprogrammed. The injectors may need to be cleaned also to help the engine run smoothly out of gear. The engine tends to go real lean out of gear and can cause the rough idle. This is normal but the rough idle is not and dirty injectors can cause it.

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