I am attempting to help a friend solve this issue.
It runs ides but rough. Cylinder 3 misfire code and no other code. Replaced rear bank of coils. no change.
Pulled all coils and injectors to visually inspect for spark and spray all looks good. compression at 208-211 on all 6.
Before spark and injector inspection I sprayed starting fluid everywhere looking for vacuum leak and nothing was found.
Any help out there?

 

Swap cylinder 3 spark plug to Cyl 1.
Swap cylinder 3 coil pack to cylinder 2
Swap fuel injector to cylinder 4.

Clear code, drive it and see if the misfire moves to cylinder 1, 2 or 4.

 

Maybe should have stated clearer, new coils installed on rear bank along with new plugs all around. No change in code or running characteristics after that.
Removing and installing intake numerous times is not going to help anything beyond. At least in my mind.
I do appreciate the attempt at assisting me.

 

This is the process of diagnosis used at a Mazda dealership.

Feel free to do what ever is in your mind

 

Not trying to express my expertise on this by questioning the methods suggested. Obviously I am at a loss here as I came begging for help. And I sincerely do appreciate the time you and others, invest helping people who come asking.
That said , I think that new coils installed, new plugs installed, should partially accomplish same as moving them around though not as controlled as method suggested. I will be reassembling today and will put old coils from rear bank to front bank and will move the injectors around to see if anything does in fact change.
The process just seems like an invitation for vacuum leaks, that is why I question the validity.

 

Specialists bring two things to a problem:
1. Greater experience
2. Adherence to troubleshooting procedures.

I'd have suggested the same as grim_reaper - because faulty new components isn't unknown, and you can only be definitive if you can move the symptom with a component.

Remove and replace the upper intake is only 20mins, If done carefully there is little chance of introducing a vacuum leak.

 

I too have had bad new parts. I have jumped into this mid stream so some changes/attempts were made before I got in. now upon reassembly engine runs but seems to be lethargic indicating plugged catalytic. Have not run long enough to obtain codes and owner in pondering throwing in the towel on this one.
I hate not solving a problem as there are no lessons learned.

Thanks all, if we continue I will repost.