Morning all !

Hi, just wondered what the normal cold idle speed should be on a 2006 X150 XK 4.2.

Upon initial start up seems a little high, an indicated 1500 for a few seconds then settles down below 1000. Car is in the uk and garaged so no excessive cold temp etc.

May well be normal but just seemed a little high to me ?

 

May be high. Read fuel trims to check e.g. using elm327

 

Thanks, just wondering how other folks engines behave on first start up from cold rev's wise.

 

Sounds about the same as mine. At start needle jumps to 2K, once started drops to 1500 for a couple of seconds, then drops to 1k for a few more, and settles at 750 until engine warms up.

While driving it Idles around 550 or 600 can remember which but that's in gear. Never put back to neutral to see if it increases.

Seems high to me too but may be the norm for 4.2L X150 series.

 

Thanks ! That's actually identical to what mine does. Guess it must be normal after all !

Regards.

Dave

 

Guess they just want to get up and go once you turn the key (scratch that) hit the button

 

The initial high rpms may help get the oil to the top of the engine to save on wear. When I start my car I wait until the rpms come down before engaging a gear.

 

Usually on cold start the ecm's are in open loop which varies the injector pulse enriching the mixture. After a period of time as the cold start sensor gets warm the system goes into closed loop. The higher idle is in the open loop phase and when it goes to closed loop the idle reduces down to about 750 rpm. I usually have around 1200 rpm on start and wait until the idle drops before I drive away. I also put the top down at this time as the increased idle keeps the alternator charging.