2013 ford focus 2.0 GDI

Hey Paul,

my name is Marvin, and  I have this vehicle here which has a long story but short one is engine was replaced with a reman and every see to be working fine except on idle engine seems to be running a bit rough and it throws P0301 on idle after 30 mins of idle, I have scope the injector and I would like some guidance on analyzing the wave form, I’m new into scoping and I don’t have nobody to teach me so I follow your videos and learn as much as I can. I do appreciate what you do to the community. 

You may not be able to spot a problematic GDI injector with the scope. Unfortunately, that's just the way it is right now with GDI injectors. You have proved there is computer control, which a a step in the right direction. All you can really do now is verify spark and compression.
An in cylinder capture may let you know if you have mechanical issue, but I would be satisfied with the relative compression test offered on the scan tool.
A secondary ignition capture during the misfire may show you if the cylinder is running lean. You could get lucky with a current wave form of the injectors and possibly pick out one missing a pintle hump. You could also try scoping the fuel rail pressure sensor signal AC couples and sync it to an injection event to see if the suspect cylinder has a noticable difference in the drop of pressure in the rail compared to the other injectors. It has been my experience that these tests CAN yield useful results, but often times do not.
If there's sufficient spark and mechanical integrity has been verified, then the list of suspects has been narrowed down the injector. There are bench test rigs where you can remove all the injectors and flow test them into graduated cylinders while observing the spray pattern. I find this needlessly time consuming end expensive. You really just have to check what you can check and by process of elimination, sell a fuel injector.

*Update*
Sorry for very late update, I actually didn’t have a cylinder pressure transducer so I bought the kit…..

Any ways I ended up doing in cylinder pressure test, I notice not all running compressions are the same, if you look at the pictures I added you can see 1 and 4 are the lowest.
keep in mind we have swap injector 1 with 4. Misfire is still present and only throws DTC for 1 but when your look a the power balance you can see all cylinder misfire. But code only sets with cylinder 1.
If my math is right that’s a 30 % leak running.
Let me add that cranking compression test is 130 psi even on all cylinder. (Test was performed with scope)
I hope I’m not going down a rabbit hole here.
I’m guessing I should probably perform a leak down to see if I can actually see where the leak is happening.
If I can’t see a leak I was thinking checking valve clearance and from there probably do a tear down to inspect valve and valve seat

Thanks for hanging in there while the forum was down.
Interesting captures, if I didn't know any back story I would say cylinder 4 looks out of place with the exhaust plateau appearing to begin later than the other 3.
Does the apparent uneven compression show itself on a cranking compression test or relative compression test?

no worries its all good!

so cranking are all the same 130 psi using in cylinder of course. if I'm being honest its about this point where I'm lost, so any guidance would help. i appreciate it

also keep in mind scale for cylinder 3 is different. so if it seem different that why. if needed i can rescope it

If cranking compression is equal, I am willing to chalk up the difference between your individual captures to varying engine speed, at least for the time being.
If the running compression peaks in cylinder one are equal once the idle stabalizes, I would be comfortable saying there is not a mechanical issue. As long as you have verified that the spark plug is in good condition and coil output is good, I would put an injector in it.
You can move ignition components around and see if the misfire follows. Since this is a reman engine, you may be able to swap injectors around without breaking anything or messing up the seals to see if the misfire moves with the injector to prove it. GDI injectors can be tough to nail down using the methods we have available to us unfortunately.

So ignition coils were all replaced and spark plugs were replaced with OEM and we suspected injector. So we went ahead and swap injector 1 with injector 4 and misfire code is still coming back to cylinder number one, so regardless of coils and spark, plug and injector being swap. Misfire always stays on one or at least DTC come back at one only.