Hi I'm new hear and looking for some info/help I've got a 03 focus and when I was driving the other nite my engine management light flashed a few times then went off and the car started running funny. I got it trailered to a local garage there is now error code showing. And it idles but when you rev it it's missing. There is no compression on number 4 and there is 2 bent valves and spark plug is black. Could any one tel me what could of corsed the problem or how much it would cost to fix.

Any help/info would be much appreciated

Thanks Martin.

it sounds like youre timing belts slipped if youre valves are bent

Timing belt is fine.

belt can still slip and bend vavles

the belt will look fine but may have slipped round on the cam possibly due to a faulty tensioner bent valves mean the internals have went out of timing and smashed together bending the said valve so i reckon the belt slipped youre timing will be out car will missfire and run like a bag of spanners

Agreed, only two things will cause damaged valves.
Either the timing is out or the top end was starved of oil causing the valves to stick.