1999 Ford Expedition 5.4 Vacuum leak at PCV Hose
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This vehicle had no codes or symptoms that were mentioned before testing and was
just a random hookup. When Escan first came online with the vehicle, it was showing
Fuel trim out of range on both banks of the info bar lights. We decided to run a
Fuel Trim Chart test for this 1999 Ford Expedition with a 5.4 |
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This vehicle has High LTFT at lower RPM and they come down at off idle, higher
RPM. They are also even from Bank 1 to Bank 2. This type of trim pattern leads itself
to a possible vacuum leak. At idle a vacuum leak has more of an effect on an engine
than at higher RPM. After locating a leaky PCV hose we went for another test drive
and we came up with the chart below. |
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You can see here that the idle LTFT came down about 6 to 7%. The higher RPM's were
not effected. This vehicle still exhibits a higher than desired LTFT and could be
a cause of concern but the owner declined further repair/diagnosis.
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