My FCA adventure

M

megastang

New member
I have an 06 5.9 with a floorit cp3 (30% I believe) A while back the FCA went bad so I replaced it, not knowing that the floorit FCA was modified. I learned just recently about the modified FCA so I I checked rail pressure with the stock replacement FCA. Rail pressure followed the commanded pressure almost exactly. However there was terrible throttle hang when reving it in park, 2-3 seconds. I put the modified FCA in and it was 26000 all the time. After reading the DIY FCA mod I decided to try to take the modified FCA plunger and swap it into the replacement FCA. I was not able to get the plunger to move so I ended up pulling the front of the fca out and turning it down in the lathe. I don't know if it was the heat or turning it down that did it but I was able to get the plunger out.

I swapped the plunger and spring into the new FCA. Now with the FCA plugged in I will barely start, rail pressure is around 2000 psi. Unplugged rail pressure is 22000 ish. Crazy thing is that If I rev it quick with the FCA unplugged rail pressure drops to like 7000 psi.

This truck had been sitting for quite a while so I plan to change fuel filters to eliminate them as a potential issue. I am not very experienced with EFI live but I noticed while checking pressures with the new setup. Fca actual duty cycle was 71 or 72 while commanded duty cycle was 0. Is this normal?


I don't know if this could be an issue. When I took off the front of the modified FCA there was a part inside that is what actually pushes on the FCA plunger. There was a small washer on the shaft of this one (see picture in link below) Does anyone know if this is in a stock FCA?

20200104_184139.jpg - Google Drive

Parts in the picture from left to right.
FCA "body"
FCA "Armature?" with spacer on small diameter. Is the washer standard?
FCA "Nose" machined down with stock plunger

Here is a pic of the modified plunger It has rectangles cut at the bottom of the triangle as well as an additional rectangle in between the modified triangular holes.

20200104_162949.jpg - Google Drive
 
I would start with a new Un modified fca and get a baseline.

72% is the maximum pulse width the ecm can deliver, and should be opening the fca to allow the most flow to bypass the injection stroke of the pump.

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When I took the FCA out the retainer had come out and all the pieces were loose. It runs much better now. I did notice that the FCA duty cycle and MA at idle are -3ish and 1695ma and the low pressure error steadily climbs. Would more PW on the FCA map help this?
It seems to have a weird light load surging which I'm guessing is FCA related also. I have not logged it yet though.
 
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