Hello gang.
Took my car in for a bit of a rough idle that comes and goes time to time. Searched the board and it seems that the engine mount brushing is a common cause of this problem.

Well… long story short, after the testing, according to the dealer; the idle is normal and there isn’t a thing wrong with the engine mount brushing. They said that only thing that may cause this problem is AC compressor they will be replacing it. Does this make any sense to you guys?

My car is 2004 and has 9,500km (or ~5,900 miles) on it.

Cheers,
Jason

 

In my experience owning a car in Asia like Hong Kong, Japan or Taiwan, cars tend to have carbon buildup issue quite often.

It has traffic light like every 100m and you can only drive like 30 km/hr most of the time in those countries. hahaha

If I were you, I would try to clean the fuel and intake sys first to see if rough idle would go away.

 

I have had similar issues with my 98 GS400. After running fuel injector cleaner through a tank of gas, it did get somewhat better, but still some low idle and roughness.

The cure was to take apart the front air assembly so you can get to the throttle plate. With the car off, I manually opened the throttle and held it wide open with a soft piece of wood. There was a significant build up of sooty carbon on the walls surrounding the back side of the throttle plate. I went in with a soft cloth saturated with carb cleaner and cleaned the walls. I was surprised how much build up there was. I put everything back together. I started it up and the idle completely smoothed out. I have had to do this procedure every time it idled rough again. Perhaps this is your problem also.