P0300 but seeing cylinder 4 misfire

[jays99burb]

Been chasing this for too long. Started as #4 mis then went to a multiple cylinder misfire. Following list is items I have replaced to date.
Spider injection, upgraded
Cap, wires, rotor, plugs and cam position sensor
( Plugs are gapped at .45)
Fuel filter
Tps
MAF
Plenum gaskets, was in there already
PCV valve
Upstream O2 sensors
Smoke tested for lower intake leaks, checked out fine.

Something I'm seeing on live data is a low calculated load at idle, less than 7%
I'm not sure where that should be but when I plug my 4.0 ranger in I'm getting around 38% calculated load at idle.
Have not pressure tested the fuel pump yet, it's on my hit list as well as compression test.
I have pulled the valve cover on bank 2 side and all the rockers appear to be doing what they should be. Correct me if I'm wrong but a low load like that could indicate clogged cats?

 

[jays99burb]

Been chasing this for too long. Started as #4 mis then went to a multiple cylinder misfire. Following list is items I have replaced to date.
Spider injection, upgraded
Cap, wires, rotor, plugs and cam position sensor
( Plugs are gapped at .45)
Fuel filter
Tps
MAF
Plenum gaskets, was in there already
PCV valve
Upstream O2 sensors
Smoke tested for lower intake leaks, checked out fine.

Something I'm seeing on live data is a low calculated load at idle, less than 7%
I'm not sure where that should be but when I plug my 4.0 ranger in I'm getting around 38% calculated load at idle.
Have not pressure tested the fuel pump yet, it's on my hit list as well as compression test.
I have pulled the valve cover on bank 2 side and all the rockers appear to be doing what they should be. Correct me if I'm wrong but a low load like that could indicate clogged cats?

It's been a while since I've followed up on this. Fuel pressure 58 key on engine off, 55 truck running. Doesn't drop off after turning the key off. Compression test, over 160psi on all cylinders except #4 that one didn't even give me a reading. Sent a bore scope camera in there, piston looks like it's been getting a steam bath haha could explain why coolant is disappearing and the cat for the bank 2 side isn't getting hot like bank 1. So that brings me to head gaskets. I ordered the high end fel pro kit. I have the dash command app on my phone but I didn't see a PID for the cam crank sync? Is it the bar under the timing bar? Just not clearly labeled? I wanna make sure I'm 100% ready when I tear this old girl apart.

 

[jays99burb]

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[docstoy]

Looks like you got her apart , looks like a vortex, when you repost what truck is it and power train .

 

[Road Trip]

It's been a while since I've followed up on this. Fuel pressure 58 key on engine off, 55 truck running. Doesn't drop off after turning the key off. Compression test, over 160psi on all cylinders except #4 that one didn't even give me a reading. Sent a bore scope camera in there, piston looks like it's been getting a steam bath haha could explain why coolant is disappearing and the cat for the bank 2 side isn't getting hot like bank 1. So that brings me to head gaskets. I ordered the high end fel pro kit. I have the dash command app on my phone but I didn't see a PID for the cam crank sync? Is it the bar under the timing bar? Just not clearly labeled? I wanna make sure I'm 100% ready when I tear this old girl
apart.

Greetings jays99burb,

Your #4 cylinder being low due to a leaky head gasket makes sense. But at the same time I'd ask you
to make sure that the head gasket is the only issue you are facing. BTW, did you get a clear photo of
the suspect head gasket after head removal? If you did, please post that as well. My hope for your sake
is that the head gasket failed in such a way that we can see why the coolant loss and 0 psi of compression
in that cylinder. (See attached for a photo of a DD cylinder head that went from running almost the best it
ever had running a solid 70 during a road trip, to suddenly chugging with a steady miss. Shame on me for
thinking that I could simply a bunch of miles on the car without performing a little PM in the form of a valve
clearance adjustment. :0)

The point I'm trying to make is do all you can while it's apart in order to make sure that your Vortec head isn't
also cracked and/or there aren't any other issues that can affect compression before you put it all back together.

By the way, if you happen to have a pic with a 'straight on' view of all 4 cylinders on the right bank I'd appreciate
seeing that as well. Also if #4 spark plug is cleaner than the other 7 this would be good to see.

****

I might be a bit overcautious, but if it was me after I got the head reconnected and the valvetrain installed/adjusted, I would
rerun the compression test on the #4 cylinder asap. (Power to fuel pump & spark disconnected, and before adding the intake,
adding coolant, and completely reassembling the rest of the engine bay.) If the cylinder now matches the other cylinders, great!
If not, stop and re-assess what's going on.

Let us know what you discover. Best of luck with your fix --