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Rich is on to something with the ICP sensor, 26% at idle is high. 11-12% or so is normal. A queasy ICP could be the cause of the blip at idle too. Any oil in the connection? Wires look ok?
Ay Dave...on the hunch of oil in connector, i went and observed it. Alls' clean and the wiring is loomed/good bud. I got torque pro so, here ina few, will compare readings, and go from there...depending on findings, my buddy has the aeroforce gauge, and will connect that to truck and compare as well, but that wil have to be tomorrow...
That's cuz boost is calculated as: MAP - BARO = boost. at idle you can have a negative number since the actual atmospheric pressure in the manifold can be lower than at the Baro sensor.
When idling, the engine sucks pretty hard - it's a piston pump. The turbo has no real drive at idle, so the engine suck outruns the turbo blow and you get a slightly negative boost.