Hello all,

This takes a little explaining to fully describe the issue I'm having so PLEASE READ FULLY.

I've had my '06 TL for a couple years now and it has about 186,000 miles, and it's a standard. A couple times shortly after I got the car it would sort of bog down while at idle and the RPM's would go to about 500, but only for a couple seconds then it would go back to normal. A couple times while I was driving and/or stopped (with the car idling) it would just shut off completely, so I'd have to start it up again then everything would be fine. The shutting down completely happened several times up until about a year ago, but the bogging down at idle has been happening pretty much the whole time I've had the car.

Now the completely dying has started happening again (sometimes multiple times in one day while driving) but again I just start it right back up no problem, and the bogging at idle still has been happening almost every time I drive.

It's not the battery or the alternator, I've replaced both for different reasons and both are a year old. A couple days ago while the car was bogging down at idle I shut off the climate control (clicking the "off" button) to see if that would make a difference, and the idle returned to normal, so I'm starting to think it's the air compressor that might be causing this.

Any help or suggestions would be greatly appreciated, but again it's not the battery or alternator since both for me are practically brand new.

 

vacuum leak.
look throughout the engine bay for missing or broken hoses.

it may also be a clogged EGR valve.

 

Clean the throttle body

 

the throttle body would have to be FULLY blocked with carbon deposits...preventing air flow...
what one would find is a very light film, nothing that would cause a bad idle...
might even do more harm cleaning it....

The EGR valve is a good place to start, as it can easily be clogged as the opening diameter is less than a few millimeters . wouldnt take much to clog this...

 

if the clutch for the A/C compressor is melted to the pulley it can cause the compressor to run with engine on, causing similar issues. If this was the case, pressing the A/C off button would have made little to no difference.

 

Be careful cleaning the throttle body, its easy to mess up these electric throttle bodies if you don't follow the proper steps while cleaning.

Another vote for checking for vacuum leaks, and maybe trying to do the idle/throttle body relearn procedure if you can find the means (I think you need software, but someone feel free to correct me).

My car exhibits similar poor idle behavior in general but also with the AC on especially - and something in the compressor or clutch makes awful noise while engaged. I intend to replace mine eventually but have no idea if its related to the idle issues in either of our cases.

 

Thank you all for the replies. I don't have a continuous idling issue or a "rough" idle at all, this bogging down happens when the A/C gets turned on. If I left the A/C off forever, this issue wouldn't happen again, which is why I think it must be compressor related.

I'm not sure what the EGR valve is, but if that being clogged or blocked in any way causes a rough idle then that would be a constant condition, which I don't have. Same thing with vacuum leaks, I'm not sure how that would cause the issues I'm having but I'm not sure.

 

If the A/C system has an issue (compressor is failing, hard to move, etc) it can bog down the engine. Have a shop check the a/c compressor/system. They can vac out the system, look at the drier (filter) and see if there is metal in there. If there is you'll need a new A/C compressor and condenser plus a flush of the lines and system to remove debris.