As I've mentioned before, and as we all know, forums are often a mixed blessing. With the Jag stalling off the throttle and providing sporadic moments of terror, a little research produced a long list of potential problems and few certain fixes. The main positive (I think) was that this was a common issue.
Arranging the various jobs by price in ascending order and starting at the free end, I showed my list to colleague Lewis Kingston, who instantly suggested a good clean of the throttle body was the best place to begin. With that, we ventured into the car park.
Armed with some silicon spray, contact cleaner and old rags, we lifted the bonnet, undid the hose clips securing the air flow meter and lifted it out. We were greeted by a distinctly oily throttle opening, which was dripping the stuff onto the throttle position sensor directly below.
After giving the throttle opening a good spray with carb and intake cleaner and wiping it clean, we unclipped every sensor we could find and gave each a good spray with contact cleaner and a decent dry, before reattaching.
Next was the throttle cable. When left for a few days, the Jag's throttle tends to stick around halfway, but pressing through it loosens everything up. It has always been a little slack, too, but I'd forgiven it that after its 150,000 miles of service.
A certain amount of cable adjustment is possible using a manual adjuster in the engine bay, so we eliminated as much slack as possible and regreased the cable to ensure a smoother action. That'll do for now, but it will need to be unclamped and pulled properly tight in time.
Air flow meter back in place and tightened more securely, I climbed into the Jag for the first test run. It was understandably a little lumpy at idle to begin with, but it soon returned to its trademark silken hum. The next nine miles of stop-start traffic, short full-throttle blasts and lots of off-the-throttle coasting were no trouble at all.
So there we are. Cleaning the throttle body was encouraged on the forums, cost very little and seems to have solved the problem. Of course, it could be something else entirely, so I will report back. Right: now that it's working again, time to investigate DIY paint kits.
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