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Discussion Starter · #1 ·
I have an lbz and when it’s warmed up dfrp and actual frp read 4.3-4.5 , when it’s first started though they read 6.2 . Is this normal ?
 

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Thats normal
 

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Fuel pressure is used along with injector on time to regulate the amount of fuel delivered. As the fuel use increases so does the pressure. When the engine is cold it takes more fuel to overcome the resistance of thick oil so pressure goes up a little. When it warms up and the oil thins out, engine load decreases and the pressure goes down.

Your numbers look about right. It would be odd to have problems with pressure at idle, though it can happen. The more frequent problem is to not be able to make maximum pressure under heavy load. That is typically caused by low pump output, air in the fuel or really plugged up fuel filters. It could also be from a leak in the high pressure fuel system but you'd probably notice the fuel running onto the ground if that was the case.
 

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Discussion Starter · #4 ·
Fuel pressure is used along with injector on time to regulate the amount of fuel delivered. As the fuel use increases so does the pressure. When the engine is cold it takes more fuel to overcome the resistance of thick oil so pressure goes up a little. When it warms up and the oil thins out, engine load decreases and the pressure goes down.

Your numbers look about right. It would be odd to have problems with pressure at idle, though it can happen. The more frequent problem is to not be able to make maximum pressure under heavy load. That is typically caused by low pump output, air in the fuel or really plugged up fuel filters. It could also be from a leak in the high pressure fuel system but you'd probably notice the fuel running onto the ground if that was the case.
The only cause for suspicion for me was an intermittent knocking noise upon acceleration . I can’t seem to figure out what it is
 
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