Originally Posted by
grizz1
The high reving after WOT run (machine gunning) is normally associated with a lean top end / maybe rich bottom end combination, or a very lean bottom end.
With the erratic idle, if the idle goes from normal to high this usually indicates an air leak somewhere. If it comes in high and drops this indicates a rich bottom end with a too wide idle gap (and normally too lean a top end to compensate).
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the better way to say this is... if the engine comes off a high speed run ( WOT ) and comes down in stages.. you'll hear it. too rich on bottom OR to lean on top. *FIRST*lean LSN slightly and slowly until it goes. or what grizz said about air leak.
otherwise richen top if it wont disappear via leaning LSN.