4.0L SOHC is revving high. | Ford Explorer Forums - Serious Explorations

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4.0L SOHC is revving high.


New Member
June 17, 2010
Reaction score
City, State
Chicago, IL
Year, Model & Trim Level
99' sport 4.0 SOHC
MY 4.0 SOHC engine races directly to the highest rpm....I just changed the plenum and Intake manifold gaskets...whats wrong with it now?

Nevermind the throttle was being held back by the linkage. But after two starts and revs all the up to 6000 rpm...the engine is making a squealing noise? Is that from the coolant being spilled on it from the thermostat change? Or did it revving that high mess something up...BTW are the intake gaskets supposed to be see-able in the middle part of the upper manifold/plenum where both meet?..(viewing from the either side with your head about level with the EGR).. the screws are torqued to spec and both manifolds are meeting... but on each side i can see the gaskets...just wondering if thats just how its designed or if i did something wrong...thanks in advance

Welcome to this forum! I've renamed your thread, and moved it into the stock 95-01 section. It sounds like you might have a vacuum leak. Spray intake cleaner onto the side of the gasket to see if the idle changes.