Oil light comes on, yet there appears to be sufficient oil in the engine

Oil pressure sensor, or most likely, oil level sensor, either sensors, wires, or connections.

The oil light comes on when the oil pressure sensor detects low oil pressure. The amount of oil has little to with it, although very low oil levels can cause loss of oil pressure. The best thing to do is to have the engine's oil pressure checked with a mechanical oil pressure gauge to ensure that the oil pressure is sufficient at all operating speed and temperatures. If the oil light is still flashing on and off and there is no indication of low oil pressure by the gauge, then replacement of the oil pressure sensor is recommended.

You need to find out why you have low oil pressure. It is normal that as engine rpm's increase, the oil pressure will rise- the oil pump is moving oil faster. Even though your light goes out, you could still have critically low oil pressure. There should be sufficient pressure at idle to keep the light off. The light will come on when your oil pressure is almost nil- I believe for some it's as low as 8 psi. Normally, oil pressure at idle is specified anywhere from 15 to 40 psi. You would have to check specifications for your Expedition. To verify oil pressure, hook up a mechanical gauge at the oil pressure sending unit on the engine block. Check with a local shop.

The causes run from easy, simple to budget busting ruin. Low oil level, wrong grade oil, real old oil, oil leaks, internal oil leaks, worn oil pump, worn crankshaft bearings. It was pretty common on older very high mileage cars to have a fluttering oil light at stops and idle. It was time for a rebuild, or time to look for another car.

Sounds more like an engine idle issue than a oil pressure issue. If the engine idle drops too low, the oil pump cannot provide sufficient oil pressure. If there is no oil light when the engine is idling normally, then there is no problem there.

check for oil pump and filter problem as it appears that the pump is not receiving sufficient oil at high rpm's

To see if this is anything that you can repair, drain the oil, change the filter, put new oil back in. If the problem is still present, the oil pump may have failed or the pick up tube has come loose inside the oil pan.

may just have been a faulty sensor , oil level being ok doesn't mean getting sufficient oil pressure

The oil pump may be going out - the light indicates the pressure is below the proper level and when you step on the gas it spins faster/raises the pressure back up to an acceptable level.

This is something to get checked RIGHT AWAY, as these cars have a history of engine failure....possibly due to low oil pressure.

Check this LINK for more info.

The emissions system may be related, but get the oil pressure issue fixed 1st.

GL,
TD

is this the oil pressure light? if it is u will need to hook up a oil pressure mechanical test gauge and verify you have sufficient oil pressure, the light may be right, if it is you are going to burn the engine up.

very concerned...have a mechanic check the oil pressure.. Don't drive it.