Anyone know how the XK8/R actually regulates the idle speed of the engine? I can think of some possibilities but do not really know how it is done. Any help in understanding this would be great!

My guess is that the throttle valve motor adjusts the butterfly valve until the voltage from the throttle position sensor reaches a target value (e.g. 0,5V). This would explain why adjusting the position of the sensor affects the idle speed.

At the same time, it would seem more sensible if the throttle valve motor would adjust the butterfly valve until the engine speed sensor sees that the target (idle) RPM is reached. Does the MAF sensor have any function in the idle speed setting?

In general, it would be good if there was a website that explains how things like the MAF sensor, throttle position sensor, engine speed sensors and injector timing are combined to govern the engine speed and torque. Anyone know where to look?

 

See the Engine Management and Electronic Throttle papers presented at product launch by Jaguar in 1996 to the technical community on my website here:

http://www.thejagwrangler.com/jaguar...nd-papers.html

It may not be everything you seek, but it gives you the basic concepts.

 

I have the training guides on my page if you want to take a look.

Link Training guides JagRepair.com - Jaguar Repair Information Resource