2001 5.4 low idle, hissing, misfire(s?)
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2001 5.4 low idle, hissing, misfire(s?)
Working on a 2001 expedition 5.4, 160k miles. bought it with a misfire. It idles at 400 rpm, and i can only start it with my foot on the gas and slowly let it down to 400 rpm or else it stalls. Figured it was a coil, some are OEM and others are a mixture of aftermarket excitement. just to test I pulled the plugs off the cops one by one to check and see which ones were bad as I have no obd reader and the vehicle isn't registered ( it's a flip car). Seemed that sometimes some would be okay and sometimes the same one wouldn't make any change in idle. Started pulling coils for a visual and 5-8(drivers side) all tubes had coolant over the top of the spark plug. Pulled #4 and it looks dirty but dry as a bone. Cleaned, dried 5-8 and coil boots, replaced spark plugs on that side. This made little to no change. I notice a massive hissing sound behind the throttle body, more so on the driver's side but cannot find any loose or broken hoses. Where should I begin looking next? And could the obviously bad intake gasket (due to the coolant in the tubes)causing it to idle low? From my experience a vacuum leak creates a high idle, but this is the newest vehicle I've worked on, so I don't know
#2