Hi when I turn the key on 2009 fiesta I hear a click and the starter spins but doesn't turn the engine ,I have just changed the starter motor and solenoid but it's still the same

Might be stating the obvious here, but have you checked the battery? Lol

Oh wait nvm the starter spins you say? But isnt engaging against the flywheel? 

if you stick you finger in the hole where the starter motor goes can you feel the ring gear (the teeth around the edge of the flywheel that the starter motor cog engages with).

or can you see in there, I have no idea what the access is like.  

could come teeth have broken off the ring gear, or could the ring gear have come adrift from the flywheel. In the old days the ring gear is heat shrunk onto the flywheel. Don't know if still done that way on modern cars.  haven't heard of anyone having a problem with the ring gear for a great many years

I've now replaced solenoid with a second hand one it's working now but not every time but since replacing the solenoid the engine now misfires and splutters revs on its own ,maybe I've disturbed something or nudged a sensor.  I took off the throttle body for access to top starter motor bolt ,when I start it now it revs erratically , I've tried the tips and methods to reset throttle and let run a while but still no joy ,it behaves like an air leak but so far can't find one was running perfect no probs till after starting it after putting starter back on ,is there a procedure on reconnecting battery  

So I took it for a drive, as well as all the spluttering and crazy revving the brakes are now rubbish takes too long to stop nearly overshot first junction, so are the brakes also computer controlled. Then on way back the engine light has finally lit up

You've definitely got a vacuum leak, the power brakes rely on vacuum from the intake.

if you are lucky you might have just accidentally pulled the brake servo pipe off.

See this pic

https://www.ebay.co.uk/itm/FORD-FIESTA-MK6-2-0-16V-ST-150-BRAKE-SERVO-BOOSTER-MASTER-CYLINDER/111847550840?hash=item1a0aa22f78:g:Ua8AAOSw6ShZW32C

your brake servo might not be identical . The black part in the pic is the servo which will be below your brake fluid reservoir. It is a vacuum reservoir used to help pull the brake pedal down.  The servo has a vacuum pipe going from it to somewhere on the inlet intake on the engine. I can't recall how the pipe is fixed on at the end but if it is off then you have no servo assistance on the brakes and poor running as the intake is sucking extra air in at that point.  so check the pipe.

As Tom says any air leak can affect the amount of vacuum for braking assistance but I would think it's quite a major leak from how you describe the brakes.

Sometimes along the length of the servo pipe there is a sort of valve. I have known the pipe to split at the join of the valve also. If something is decaying though age and heat it does not take much accidental disturbance when working on something else to break / split something.

see this pic - the valve thing on the servo pipe is at top of picture

https://www.ebay.co.uk/itm/Ford-fiesta-mk6-fusion-1-4-tdci-brake-servo-vacum-pipe-2002-2008/183405859513?hash=item2ab3d752b9:g:7qYAAOSwS9Bbhw5F

Sorted found the leak ,the dipstick bracket has snapped of the inlet manifold leaving a hole , I've bodged it back on with superglue and covered it in silicone not so confident it will hold?? But will have to do till I aquire replacement, I've not tried it yet gonna wait till silicone is cured. I'll let you all know how it pans out    do you think it will hold?   Thanks all for your help :)

 

Well it's holding for now running OK.

Changed the starter motor and solenoid but it works about one in ten attempts ,mostly just the motor spins but doesn't engage, is there a starter or ignition relay that could be at fault?

3 minutes ago, Stimpy said:

Well it's holding for now running OK.

Changed the starter motor and solenoid but it works about one in ten attempts ,mostly just the motor spins but doesn't engage, is there a starter or ignition relay that could be at fault?

The starter relay has to be working or you wouldn't get any power to the motor at all.  I assume the starter just spins slowly when it doesn't engage?  It sounds like you're just not getting enough amps through tbh, dodgy battery or wiring most likely.  Are there any frayed ends on your battery to starter cable, or the main earth cable?

The starter spins fast every time but doesn't engage every time always good when cold but if I turn off when warm it takes its time engaging on restart , I changed the motor and solenoid and no difference but it was a 2nd one so can't guarantee it was perfect

The starter spins fast   g.every time but doesn't engage every time always good when cold but if I turn off when warm it takes its time engaging on restart , I changed the motor and solenoid and no difference but it was a 2nd one so can't   i. t. .b . we.   w.  I aa qa  s perfect

As it's worse when hot that's almost certainly a wiring fault.  It's harder to push current through hot wires, check those battery cables.