Hi Tony

I am pretty sure that the injectors are shut down when the PCM decides which cylinder is misfiring. I have done many many of these & as you do, I perform an emissions test & have never seen a failed cat as a result. Fords however Their catalysts must be made to such a low standard I think.

The car that cam in on Tuesday had been in previously for a single coil, but that was 18 months ago, so the customer is not jumping up & down, but I know where you are coming from.

Cheers now

Dave