If the intake manifold is not tighten correctly, would this cause the exhaust manifold to turn red hot. Would it also cause the engine to run at a high rpm.
In take manifold on 1995 Jeep Cherokee
An intake manifold that is incorrectly tightened and allows air to be drawn in past the intake manifold gasket (causes a vacuum leak can give a high or erratic /surging idle speed and cause a misfire. If the vacuum leak is so severe that it causes the engine to run "lean" the exhaust manifold could get red hot in theory and power would suffer.
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It would also send fresh air to the Oxygen sensor which would make the computer set the mixture to full rich would would heat up the manifold, even to a reddish color.