i have a 2wd cossy saph it is running 4psi of boost runs fine but when i try and turn it up it will only give me 6psi and it hesitates and backfires as if its overboosting i have changed boost hoses taken turbo and actuator off to be checked all came back ok switched amal valve and fitted diferent boost gauge still doing same thing any ideas would be greatfull as i am very close to torching the thing cheers

 

If it backfires, then it sounds like an ignition problem.

Have you looked at the state of the spark plugs recently ? What are they gapped at ?

 

check the plug connections on the ecu also!

 

is it chipped?

 

i have checked the block on the ecu looks fine yes the car has a stage 1 baileys chip plugs are in a1 condition only recently changed they are gapped at 0.8mill motorcraft platinum thanks

 

0.8mm is perhaps a bit large - try reducing the gap to about 0.6mm

 

yes too big a plug gap will weaken spark n cause your cos to backfire like its over boostin

 

i have lowered plug gap to 0.6 still same prob also changed map sensor an pluged another ecu in still same cheers

 

all the time, or just on boost?

if just on boost = igniotion amp on its way out IF the plugs are ok...