well most vaccumm referenced FPR Ive seen and dealt with typically run 1:1 psi drop per inHg. So typically youll see around ~35 psi at the rail during idle and will rise back to static pressure at WOT and if boosted should rise proportionally to boost.***NOTE FOR THIS ISSUE ID LIKE TO KNOW THE IDLE RPM AT THIS POINT CAUSE THE FUEL SYSTEM COULD BE FUNCTIONING FINE AND ITS JUST THAT THE HIGH IDLE IS CAUSING THIS**** Reason for this is that under vaccum in the plenum there is less resistance to fuel coming out of the injectors and as vaccum drops to atmospheric, atmo pressure puts more resistance on the fuel coming out of the injector so pressure rises to compensate. This function is required in a port fuel injection setup to maintain a consistant pressure vs vaccum. The only times this is not tthe case is with TBI which sprays in atmosperic pressure always so the pressure is set at a static number and also in rising rate fuel pressure regulators which add non proportional pressure to the rail in IMO slopped together forced induction systems.. Im thinking MAP for one reason and thats the huge drop in horsepower as shown by his 1/4 mile trap speeds. If he was complaining of only a high idle id look at the idle air motor as well and it very well could be screwed up as well BUT the additional air introduced by that staying open would be compensated for in this speed density system. The only time youd see a huge horsepower loss would be when the map sensor was no longer refrencing plenum vaccuum correctly. SO Id recommend this..
1) disconnect the IAC, if the idle changes substantially we can at this point assume that it is not stuck, if it doesnt then pull it clean it or replace it and retest.
2) Check MAP voltage, it should be ~1.5-2 volts at idle what we dont wanna see is 0 or 5 volts.
3) Check your static timing with EST unplugged, if it somehow got too advanced it would idle high and would cause pinging which would cause the computer to pull timing out by a bunch causing HP loss.
If none of this fixes any problems id say get back to us.
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