'98 3.8L Oil Pressure gauge flickering....WTF?

[UltraKla$$ic]

Tonight I noticed my oil pressure gauge flickering very rapidly as I slowed down to a stop and then it falls to the "L" at a stop. It goes back to normal oil pressure gauge level when I rev or take off and only flickers and falls to the "L" when coming to a stop again.

Oil level is spot on, and no motor noise noted. An ever so slight stutter in the motor when listening to it as it idles down during this episode.

Any ideas? Are there vacuum lines that control this gauge? Oil sending unit? Oil pump? WTF?

 

[UltraKla$$ic]

Can the cam position sensor be bad, or the alternator, or both? Maybe the RF signal from a bad alternator is "cross-talking" with the cam position sensor hence the irradic oil pressure gauge since the cam synchronizer runs off the oil pump?

Possible?

The car does not burn OR leak a drop of oil. The motor pulls like a freight train and the motor has been compression tested and checked out perfect.

 

[Skymarshal]

If it's rapid movement, it's probably just the harness or the sensor. The oil pressure sensors are known for going out. They're like $10 at the dealer and easy to replace.

 

[MustangLX-5.0]

I have had this problem for years.I spent a lot of time diagnosing this.

Let me try and explain this briefly.The oil senders on most newer Fords including the Mustang are NOT variable pressure senders like they are on..say a 92 5.0 mustang or F-150.The newer senders are simply on/off switches..Very dumb and a cheap idea of Ford.When the oil pressure is below 7 psi,the signal output reads 0 volts...or the gauge needle is fully to the left.When the pressure is above 7 psi,the pressure switch turns on and reads 5 - 6 volts....or the gauge shows the needle within the middle of the gauge (around "RM" in "NORMAL").So...its either "On" or it's "Off".If the needle flickers around like that,the cause can be a couple of different things.The most likely culprit,a bad pressure sending unit.An internal seal within the sender goes bad and oil gets into the electrical "pressure switch" causing variations in current flow output.Oil is an excellent insulator and extremely poor conductor.

The other possibility...as Skymarshal pointed out, a bad ground.Check the wiring to the sender pin.Remove it, scuff the pin with a wire brush then spray it with electrical contact cleaner.If this doesn't fix the prob..then replace the sender.If you do replace it,DO NOT buy one from Autozone.They have the worst quality.

 

[UltraKla$$ic]

Thanks for the input! I did change the oil sending unit and have the scars to prove it! LOL

It seems fixed at present. Crossing fingers!