I agree. It seems that fully depressing the throttle several (5) times in succession cured the problem. I have been thinking something might have been sticking such the throttle or the cable.
I'll update as time goes on or if the problem reoccurs. Just to recap, the problem worsened the longer the run rather than when it attained a certain temp. (Beyond an hours running or so). Anyway, the 5 depressions may well have cleared a mechanical problem rather than reset the ECU and given what I now know I'll first check mechanical issues if it reoccurs. And the experience and your comments have been most helpful. Thank you!
I think some of these cars can continue to warm through for quite some time (and distance!).
It's just that most people report erratic idle and throttle issues when just started, improving as running time and temperature increases.
Anyway, it's good that the car's running well now and you've got some ideas should the problem return. Fingers crossed it doesn't!!
I'm revisiting this thread as I still have a tickover problem, although slightly different..
The tickover became more erratic and on the F&C run it continually cut out at junctions/light etc (it would die as soon as revs settled at about 1,100rpm). It started fine following each cut out but wouldn't tick over. The cutting out was solved with a change of lambda sensor but now the tickover settles at anything up to 2,000rpm. I'll pull up at lights for example, and it'll be revving away. At cold and until run for 30mins or so it ticks over fine and settled at about 1,000rpm. It has a locked Caterham ECU.
a) Download Easymap, buy a cable and try to identify the issue? (I'd learn a bit about the car more but may not actually be able to fix the problem, or
b) Get it back to Caterham who 'should' be able to fix it, or
c) take it elsewhere? (where? I'm in Hertfordshire)
I would be looking at the throttle pedal pivot, and lubricating it
If blipping the throttle when the idle is higher than it should be causes it to return to normal, it is highly likely that the throttle is not returning to the stop position. Other than lubrication as suggested above, a fraying or jamming cable at the pedal end (precursor to the cable snapping), too much tension on the throttle body end (needs to be adjusted for a bit of slack), weak return spring, over tightened air filter (causes throttle blade to jam slightly open) or loose throttle blade are all things to check.
While the idle is elevated, take off the bonnet and press the throttle linkage against the idle stop, if that fixes the issue, then the above checks should be done to identify what is preventing the throttle blade from closing to the idle position. If the idle is still elevated with the throttle against the stop, I would check for air leaks in the intake system, ensuring all nuts and bolts for the manifold and throttle body are tight and any vacuum lines or blanking plugs to the manifold are tight and puncture free.