Car won't start when engine is warm

[Lewin]

Washed car on Monday and since then it won't start when the engine is warm. Won't even turnover. Turn the key and nothing happens (except radio goes off as normal).

I've searched and seem that the tdc fails but that seems to relate more to a car that turns over and doesn't fire up.

Anyone got any ideas?

After a couple of hours it will start again. Have I got water somewhere I shouldn't?

Also had some wiring work done to the throttle system but don't think this is the cause.

Thanks

Mike