My 2002 crown vic is misfiring and the check engine light flashes when speeds of over twenty miles of hour are reached. Is it safe to drive. How can I fix this

Engine Misfire diagnosis can be complex and there are many reasons for misfires to occur. I suggest you read the article at this link that deals with engine misfires and the diagnosis of them and possible solutions to repair them.

Hello

The Engine and Automatic Transmission (not applicable to manual transmissions) in this vehicles drive train are fully electronically controlled by a computer called the PCM and TCM (Power Train Control Module, Transmission Control Module). When a problem like this or other drive-ability related problems occurs the computer stores a record of the problem (there are of course some exceptions to this, like the fuel pump, engine coolant temperature sensor and MAF sensor for instance) in the form of a fault code in its memory, to read these fault codes you must have the systems memory scanned with a special tool. Once the fault code(s) are read you then must perform the appropriate diagnostic testing to find and resolve the problem(s) DO NOT REPLACE ANY PARTS UNTIL A TRAINED TECHNICAIN HAS DIAGNOSED THE PROBLEM TO AVOID SPENDING YOUR HARD EARNED MONEY ON PARTS THAT MAY NOT CORRECT THE PROBLEM. Also always check fuel pressure for correct spec for your make and engine type.

Definitely have to remove the driveshaft on a rwd crown vic, or you have to leave the engine running and the car in neutral to keep the transmission lubricated

When the check engine light is flashing, it means that the system has detected a misfire condition that can cause damage to the catalytic converter if not repaired. Try to drive the vehicle as little as possible until the problem can be addressed. Look for bad coil pack or shorted injector or driver

I would start with plug wires rubbing on something and created a short.and is not compleatly worn through. a cheep place to start. good luck with it.

the check engine flashing means the engine is misfiring and can cause catalyst damage ,have it looked at right away,lots of problems with ignition coils and ignition wires causing misfires

I would try to replace your spark plugs, and spark plug wires, My 88 Vic did the same thing...now it runs like a champ....you could also try fuel injector cleaner.

You say you changed the cam sensor. A1391 code is a crank sensor on the top of the trans. bell housing.

I just came up with that exact issue in my 2003 with 98K police crown vic. And the last time I had this issue in a 2001 police Crown vic it was the crank shaft position sensor. A $20 part and about 30 mins to put it in. located near the bottom of the engine. I had to un bolt the A/C compressor and push it out of the way a few inches to get to the sensor. If you have about 100K mile on it and its an idled heavy police car, this sensor should be changed out anyway. It can leave you on the road dead and some dealers have a hard time find out whats wrong as the OBD 2 does not see it as a problem when it goes bad or becomes touchy as I think mine is.

take a look at the EGR valve it could be either vacum controlled or electronic either way what seems to be the problem is that the valve is stuck in the open position until the engine warms up you can gently tap the egr valve with a small hammer or a screw driver and you can see that it runs smooth, now if the egr valve is vacum controlled replace the valve. if it is electronoc controlled replace the valve and the module for the egr valve.