my 2004 opel astra 1.7 cdti (yes i live in france) runs fine when its cold but usually when its hot and dry the engine loses it's torque and runs like a fiat turbo diesel from ten years ago. the power is still there but theres no elasticity and the engine's horrible touse; really peaky and gutless. then when it gets cold its fine.
its under guarantee so i've had it back to the garage twice and each time they've said its fine (probably gave it to the spotty apprentice for a thrash around the block and then plugged it into the computer for five seconds)
i'm no mechanic but it sounds like a sensor is telling the engine management bad information
what do you think ?