Took the S1 out yesterday and was fine, then when opening it up it hesitated or jolt then seem to hold back, I backed straight off but it happened again when I tried it again. The car has a fifth injector on it and it was towards top end boost. no smoke or anything came out the back and it runs fine.

Could it be the fifth injector not kicking in and starving it of fuel (I imagine this is not a good thing) and if it could be is there any way to test it.

Don't really want to try it again as I am scared of melting the motor or blowing it up.

Any help would be

Cheers

Matt