Idle questions,

[Kaz13]

Hey guys,

I have a '05 4.8is with 120km, and it has an intermittent idle issue.

Here are the symptoms...

-Idles perfectly when cold. No cold start issues, has always turned over first try.

- Once warm, it is still intermittent. When it does idle roughly, there are no RPM changes. Sometimes it idles roughly and is constantly rough, other times it idles with a cycling, "whomp" feel. It feels like it is cycling, and the vibrations varies in its intensity.

-Just tried the A/C and with the AC on it minimizes the vibration.

-In drive , it is slightly more powerful than when in neutral or park, but not completely eliminated.

Wondering if anyone has any ideas on where to start with this issue, based on past experience? I am thinking it is a vacuum leak, due to the cold motor not having the issue.

Do 4.8is motors have a Idle Control Valve? Have not seen a DIY to clean it , and I have searched. Seems the 3L has the ICV, all of the DIYs are based on that motor. I don't not have my bentley manual yet, so sorry if that has been asked before .

Looking forward to contributing and hearing the wise Xoutpost members opinion

Cheers,