12-06-2006, 10:09 AM
Join Date: May 2006
Location: Elkton, MD
Thanked 8 Times in 5 Posts
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It is louder when cold then it is when it's warm imo.
As for the "knock" it could be injector cackle. Speak with Shane "sea71" about it... he has it as well. It's apparently air in the fuel system and usually comes from the #8 injector I think...
I used to have a sound clip but I can't find it. If I find it I'll post it up so you can hear it and compare it to yours.
Ok here is what I found..>
want causes the sound
A convergence of poor design decisions that maximizes the deleterious effects of HEUI systems in general and entrained air in your fuel system in particular.
, and why is it louder when cold and other times?
The fluid viscosity of your fuel and oil is lower when cold. This affects the fuel spray pattern emitted by the injector, which in turn affects the entire combustion event. The oil viscosity is also one of the variables that affects injection timing, so the timing and the combustion event itself are both a little 'off.'
can you stop the sound or make it quieter?
Mine is completely gone now that I've added the in-tank mods, an Airdog, a pressure-regulated recirculating return fuel system, the high-pressure oil rail crossover mod, and a standard injector in the #8 hole.
Dennis Schroeder at ITP in Phoenix can set you up with all of the parts necessary to kill your cackle.
On several occasions I have astounded my fellow 7.3 owners when I start it up - the difference in smoothness and noise is that stark.
The in-tank, Airdog, and HPX all chipped away at the flanks of the cackle problem, reducing its RPM range and its overall tendency.
The fuel system and LL8 replacement completely eliminated it. My PSD is a smooth as a straight six.