I have a 2004 Acura TL automatic. The past couple of days my TL has been having idle issues. When starting from a cold engine the car is fine, as soon as it warms up the issue begins. when I am actually driving and giving it throttle the car runs fine. It is when I stop at a red light or for more than a second the car begins to drop rpm, as it drops the car vibrates through the steering wheel and floorboards and the engine corrects the drop rpms and goes back to normal. It kinda feels like the engine is misfiring in idle. Now if I put the car in neutral the vibration is reduced a fair amount, however, you can still see the RPMs drop and rise. This began to happen after a heavy rainstorm. I do not know if that could be a factor. Also, I did an oil change a week prior to this issue surfacing. This is the first oil change I did to the car since purchasing 1 month ago. I am not sure if conventional oil was in it put I used full synthetic when changing. I am reading a lot of stuff it can be, everything from EGR valve, to spark plugs, vacuum leaks, to even motor mounts. Was hoping someone can maybe point me in the right direction in tackling this idle issue.

 

a surging idle is a tell tale sign of a vacuum leak. look for busted or open hoses.

the stock motor mounts operate on a vacuum....look for disconnected hoses at each motor mount...then look at the back of the intake manifold for busted or disconnected hoses

 

Thanks justn ,Will do, tomorrow morning I will take a look at all the vacuum lines you have mentioned, I will be cleaning my throttle body tomorrow is there anything I should take a look at?

 

You can spray carb cleaner around vacuum lines and the intake area and see if the idle jumps. Sounds more like the vacuum lines for the motor mounts though.

 

Yeah, I wouldn't mess with the throttle body... Would just look for vacuum leaks

 

Ok, so after checking all the lines everything looked pretty good. I shoved the hose going to the front mount and it felt like it sat better in place, like it was halfway to coming out. I also pulled 1 plug to get a look at the shape of them since I have not changed them since purchasing the car. I will attach a picture of the one plug I pulled, You guys think I should change them all out? But anyways, after inspecting all lines and pulling a plug I put everything back together hook up the battery and voila! the engine has yet to rough idle again. I have only driven it a couple of miles and the engine has been running for 35 min but so far it hasn't surged again. I am not sure if it was the reset of the ECU by unplugging the battery or shoving the vacuum line into the mount further but the engine seems to have lost its rough idle. I will do some highway driving and really open her up and see if my results and consistent. Also please let me know what you guys think about how this plug looks.

 

Plug looks mint. Brown indicates ideal air fuel ratio. Problem most likely lied within vacuum or reset.