Misfire insignia 1.8 petrol cylinder 4

[mrk]

A lad at work has read codes and got this fault. He's replaced plugs and coil but it's still the same. Any ideas?
Cheers

[Big Dave]

What did he use to extract the code(s)?

Post the code here so it can be cross referenced as to being the correct diagnosis.

[mrk]

He's going to check. Thanks

[Big Dave]

Another thought, (and sorry if it's sounds like I'm teaching grandmother to suck eggs)

He did identify cylinder 4 correctly and not cylinder 1 by mistake? Cylinder 4 is usually furthest from the cam belt on a 4 cylinder engine.

[mrk]

P0004 has done a compression test 160psi on cylinders 1 and 2 nothing on cylinders 3 and 4.
Cheers

[mrk]

P0004 code

[Big Dave]

P0004 has done a compression test 160psi on cylinders 1 and 2 nothing on cylinders 3 and 4.
Cheers

Did he then add a small amount of oil to see if there was an increase in compression? If there wasn't, then one or more valves could be leaking, or a crack in the block or head.