hi my mates got a sierra cosworth as soon as u get to 3 grand or onto boost it back fires and cuts out any ideas

 

Check crankshaft sensor and phase sensor.

 

As above then check plugs/gaps try closing them a bit and see if it helps, especially check the connector on the cps by doing the wiggle test whilst idling to see if it stutters etc.
tabetha

 

As tabetha says do a wiggle test , sounds like a HT/coil break down as soon as the plugs need more voltage to spark so closing gaps may help slightly , possibly king lead , rotor arm distributor cap , have a real close look at all these , check resistance of king lead then go from there

 

hi changed king lead and ht leads new rotary arm and dizzy cap and plugs also any one know the gap setting for the crank sensor

 

As far as I know the gap should be 0.6 to 1.0 mm , and check all 4 just to be sure that pulley is ok