alright guys new here and in desperate need of help, ive got a 1.6 focus mk 2 that is missing on cylinder 1 at idle and initial take up of drive. so far i have changed plugs and leads. checked the wires to the coil pack for corrosion swapped injectors on 1 and 2. put on ecu reader and came up with cam sensor weak signal so replaced cam sensor.The only fault still showing is misfire on one or multiple cylinders. also checked to find any vacuum leaks with no joy and now it is really starting to pickle my head and im really hoping that it is something simple that i have overlooked before i go and get a compression tester. 

 

Have you changed the coil pack? 

yea forgot to mention that i have done the coil pack aswell

The ecu could need checking out 

I'm assuming you changed the coil pack with a NEW one from a reputable brand? Not one from a scrappy?

Have you swapped the fuel injectors between any of the other cylinders? or just between one and two?

Assuming plugs are clean, and spark gap correct?

Compression test would be useful just to rule out a low compression in Cyl 1, do the codes point to an individual cylinder at any point, or just "Multiple/Random"? What was the code the initial reader gave (just in case it's actually a code for something else)?

yes it was a new coil pack but have since found out that coil pack with a miss on only cylinder 1 is unlikely to be coil pack as it would normally be a miss on 1 and 3 or 2 and 4.

plugs are brand spankers and getting a lovely spark off all 4.

only swapped between 1 and 2 as 1 is the faulty cylinder so as the fault didnt move from cylinder 1 to 2 surely this proves it is not an injector fault.(maybe injector wiring but def notinjectors)

didnt get a code number did originally say cylinder 1 but since changing cam sensor now says multiple/randomn

How did spark plug one look compared to the others?

Hi you could try swapping the loom plugs between 1&2 to see if the misfire goes to number 2 cylinder 

plug 1 is slightly burnt i will swap loom plugs at weekend unless by some miracle i get time during the week

Thinking about it not too sure that swapping the connectors for the injectors will work as it may need to spray fuel into the manifold as a specific time sorry for the wrong information 

Good luck

Injectors do indeed fire at a specific time so you can't swap the leads. With the wasted-spark ignition system you can, in principle, swap the HT leads of a coil pack.

As an interesting aside, the Bosch D-Jetronic system fitted to VW 411's had pairs of injectors that fired simultaneously with the fuel from one injector having to 'wait around' in the manifold for that cylinder's induction cycle.

Thought this was the case sorry Richard for the bum steer hope you get it sorted 

Might sound stupid (and yes I know you have changed the leads) but have you actually checked the leads with a multimeter? Even with new leads, one could be a duffer.

i have not tried testing leads with multimeter but i do know i am getting a good spark at all plugs. i am starting to lean towards piston rings as can smell fuel on the dipstick.

A compression test should give you an indication of a piston ring problem but I suppose you already know that 

Sounds like a burnt exhaust valve to me.  The 1.6 engine can be prone to this issue.  Unlikely to be a cylinder sealing issue unless the engine has been run low on oil or hasnt been serviced.  Compression test and cylinder leakage test should confirm this issue.