cynic wrote:
Well I took a look but the promised rain came on almost immediately so
I've called it off for the day. I think I found the throttle
potentiometer - a shiny round metal component on the pedal axis.
Problem now is going to be actually getting to it without taking the
drivers seat out. Its tucked up tight into the corner of the drivers
footwell behind various obstructions. There isn't any obvious signs of
dampness or corrosion from what very restricted view I did have so I
might have a search round for a local small firm diagnosis service
since the agency were talking £80 plus VAT. At that price I could
justify a connection lead and some software if its anything like
reasonably priced.

It isn't.

I had some dealings with a company that does third party software and
diagnostic help for ECU's and so on.. the manuals are thick and heavy,
and so is the kit, and they owed their existence to the fact that very
very few garages actually knew how to use it.

In the one case where I had an injection issue, they and I were correct
in our diagnosis. The garage I took it to were not.

The info is closely guarded by the manufacturers, and they tend to
release it (they have to under EEC rulings) in as terse and unreadable a
form as possible.

I am 99.99% certain that diagnostics will not tell you what you don't
know already. It's that shiny round component on the pedal axis..or
rather the wires attaching to it in all probability.

You won't see any obvious signs of corrosion. That will all be inside
the spade terminals or whatever it uses to attach to the wiring.

A good blast of contact cleaner and a wiggle may fix it even if you cant
get the wires off. A good wiggle with the engine running may well induce
the fault too.