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Question regarding the boost gauge. I used the power elbow tapped port for my boost gauge. After I did that, my boost needle vibrates from 25 lbs and up when under load. What is the cause of this ?
Well if you are getting excessive needle flutter either the gauge is defective or your turbo is surging (usually do to sticking vanes or bad actuator).
How many miles on your truck and what mods?
Well as stated previously, it could be a deffective gauge, turbo surging do to sticking vanes or bad acutator. It could also be caused by your A/M air intake or the tunes in the SCT.
i am refering to dynamics of pressure in a closed system, reading with a simple mechanical gauge of course you will see fluctiations thats what i'm saying, what you wont see (without a rapid 120 to 240 hz transducer) is a accurate representation of true system pressure at any given moment, & given the inconvience of strapping a multi chanel oscilliscope onto the dash a mechanical gauge is good enough as a average system pressure is all we need to see, therefore point of sample is irrelevant & the map sensor hose is exactly as accurate as the elbow,as is the compressor outlet. Does this make more sense or am I just forgetting my theoretical physics (it has been 21 years) that is possible!
i am refering to dynamics of pressure in a closed system, reading with a simple mechanical gauge of course you will see fluctiations thats what i'm saying, what you wont see (without a rapid 120 to 240 hz transducer) is a accurate representation of true system pressure at any given moment, & given the inconvience of strapping a multi chanel oscilliscope onto the dash a mechanical gauge is good enough as a average system pressure is all we need to see, therefore point of sample is irrelevant & the map sensor hose is exactly as accurate as the elbow,as is the compressor outlet. Does this make more sense or am I just forgetting my theoretical physics (it has been 21 years) that is possible!
You are probably correct that the sample point is irrelevent. But lots of people have reported excess needle flutter by tapping into the MAP line , myself included. I tapped the stock elbow before I got the power elbow and the fluttering needle went away.
I have a theory as to what causes the needle flutter when tapped into the MAP line. My theory is that since line deadheads at the MAP sensor and the line carries less volume each time the intake valves open the drop in pressure is registered. I left the T in the MAP line and when I switched to the Isspro gauges I tried the MAP line first and then went back to the elbow as it had the same fluttering needle issue the Western Diesel gauge had.
Last edited by OregonF350; Jul 5, 2007 at 06:45 PM.