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Originally Posted by yundar
Hey Thanks, I do have the gauge set but from what I have been reading I am confused on what control pressure is on KE-Jet. Sounds like with the lambda system the bottom side off the fuel distributor is different? I have removed the fuel injectors and bench tested them and they are within spec. Yes, the flooding is in all cylinders equally.
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Can’t help on the FD but I can help with fuel pressures. System pressure is your baseline fuel pressure. If it is out of spec (usually too weak) then the other pressures don’t matter. System pressure is higher than control pressure — generally system pressure is in the 4.5 bar range and warm control pressure is in the 3.5 bar range. Broad generalization — don’t get too wrapped up in the specifics.
The control pressure is variable and measured in two states: cold and warm.
Picture a see saw in your mind. As air going into the intake pushes up on one side, the other side is pushing down on the plunger in the FD. The control pressure is the resistance against the downward plunger force.
The lower the control pressure, the lower the resistance. Higher control pressure, higher resistance. Lower control pressure, more fuel. Higher control pressure, less fuel.
On a cold start, you need a richer mixture so the control pressure is lower. Once the engine warms up, the mixture leans out to normal (close to stoich). Under load, you need more fuel to make sure you don’t go lean. This was accomplished in different ways over the years. Measuring CCP and WCP is making sure the mixture is correct in these two states.
The WUR “bleeds off” system pressure to act as a CCP and WCP regulator.