Weird issue occuring

[BagelBoy]

So got a weird issue going on that I figured the wizards here might know. I recently swapped my fuel lines to -6an PTFE fuel lines, and installed a new DW fuel filter 10 micron and its size is 110mm with -6an fittings. I also installed the -6 an bulkhead fitting from STM at the hanger so its all ready for my future e85 swap. Now I get a weird stutter in 5th gear where its cutting in and out before 3.5k rpm and I get a lot more knock throughout the gears. I verified my spark gap on 7es at .028, compression test is 140 across, BLT was fine at 30psi, base timing was still good at 5 degrees, and my AFPR is holding at 43.5 with vacuum off. I didn't have this issue before swapping (I had a very slight knock but it was ok at 2 degrees full WOT around 7.2k rpm) but now it fills up to around 5-9 degrees knock on ecmlink. Basically I am stumped on what else to go through and was hoping if anyone here had some directions for me to go. I believe its fuel related but I am really stumped as it shouldn't have affected my setup that drastically and everything isn't leaking and my pump seems to be fine still. Thank you guys!

 

[Turbo99]

What does your air/fuel look like when this is happening? If that is the only variable and it is lean it would stand to reason there's now something causing fuel pressure to not rise 1:1 like it should be (which you wouldn't notice with a base pressure test).
My money is on an internal leak at the sending unit you just installed a bulkhead in that is not allowing line pressure to keep up with the demand at the rail, or something is kinked/restricted etc. along the way.
How is the pump attached to the bulkhead at the underside of the sending unit?

 

[BagelBoy]

My AFR reads in the low 11's to higher 10s but it seems to spazz out going from 11 to 9 to 11 until I get off the throttle in that short moment. My lines don't appear to be kinked anywhere and my pump is attached using submersible fuel line between the fitting and pump with injector hose clamps. Im not sure how it would leak there, the bulkhead is a -6an to 5/8th fitting with the PTFE washers on both sides of the hanger unless that is incorrect?

 

[BagelBoy]

Here is a log if anyone wants a log. I did post on DSMTuners and they stated that my coolant temp is acting funky so I will be investing that too for knock in general but if anyone has anything else I am all ears because this issue is really confusing. Also if someone opens this, my fuel pressure on my end is at 43.5psi sometimes itll open and show 37 for whatever reason but it is confirmed 43.5.

 

[r4pt0x]

My first guess would be you are overwhelming the pressure regulator due to the much bigger feed line. Pulsations in the fuel line are also possible; we've also seen them on some E85 builds with very large feed lines and huge fuel rails. Usually those were gone when fitting a quality brand fuel regulator and/or a properly sized return line. If the return line is undersized you usually get extremely rich AFR at low load/rpm even at comically low injector duty cycle values, but it can also affect how well the FPR can dump fuel when lifting the throttle from high loads (and hence high fuel flowrates).

OTOH, if you have other sensor values acting up I'd check the grounding connections of the engine and ECU. The wires between the engine and chassis tend to corrode over the years, often underneath the insulation.

 

[BagelBoy]

I don't think -6an is that much bigger than stock hardline and my FPR is from Deatschwerks so that is a good one plus I had it sent back to get tested and it came back good. I might've been stupid and put on a PTFE hose onto the return line without realizing it. I think maybe that could be the issue as its not properly sealing so when I get the chance I will swap and update here.