Another Misfire Thread

[Gray035]

One of the first approaches to miss fire/stumbling, is to do a quick process of elimination. Hand on tail pipe- is there a DEAD miss or random cyl drop off?
Ignition side- all OK plugs coils, etc
Fuel side - what is the pressure in the fuel rails? Do the injectors misfire, drip, spray patterns equal cyl to cyl?
Air intake - filter to cyl head. Clean, sealed, and not deteriorated?
Oil Separator - leaking, split, puking oil everywhere? (Mayo under oil filler cap?

Misfire can be read with a scanner. Move around cyl to cyl or stays in one cyl?
Stays- look into THAT cyl - Ign & Fuel delivery systems
Moves- look up stream - Ign & Fuel delivery systems and look for AIR LEAKS. Your smoke detection method shows a leak in the intake area at the DISA valve. Pull and inspect.

Yes. This is helpful. I've already completed most of this list:

(1) 1K on new spark plugs
(2) haven't checked fuel pressure yet
(3) the air intake has been smoke tested...will replace DISA O-ring. The DISA itself appears to be in good working order.
(4) Need to look into oil separator (aka CCV right?), but PO said it was replaced. No mayo under oil cap.
(5) the misfire is stays on cyl 5 even though coil has been moved (need to inspect spark plug and switch that to another cyl to see if any effect).

I think there's not much more I can do while I'm waiting for DISA O-ring. Once that leak is plugged I can continue trouble shooting.