1999 town car, check engine light code shows 3rd cylinder misfire...changed spark plug and coil and problem still there. Car runs rough. What next? Thanks. Ned [email protected]

AC has nothing to misfires or o2 sensors.

Start with the basics.

Check the spark plugs, or perhaps just replace them all. Or you can test, put plug 5 in plug 1 swap. Does the misfire move? If it does, the plug is the issue, if it doesn't is is the coil pack to it.

Clean throttle body and MAF.

Clean EGR

Run car for a week, and if it is still running rich, change the sensors.

OR, just go to an auto-electrician with a $5,000 scan tool computer although with a 1999, the data will be fairly basic but will diagnose.

https://www.google.com/search?q=1999+Lincoln+Town+Car+shakes+at+idle.+Cylinder+5+misfire+and+bank+1+and+2+too+rich

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Ok it has engine misfire coil pack cylinder 8 or change spark plugs when was last full tune up?

Compression check may tell you something.

Hello Frybird.

The codes you have are engine misfires.
Code 300 is random misfire (could be any cylinder).
Code 302 is cylinder #2 misfire and 303 cylinder 3 misfire.

Most common causes are ignition issues.
Spark plugs, ignition wires/boots and ignition coils.

Next would be fuel issues such as fuel injectors.
Next would be emission components such as EGR valves.
Then in a worst case condition would be engine wear parts (valves, camshafts etc.)

The place to begin is ignition as this is a common failure on most cars.

If you need further assistance regarding your question please ask me here in a comment.
Thank you for using FixYa.

KL

ck compression on cylinder could have burned valve if no could be injector or coil

change insulator and then if still bad swamp coil to another cylinder if acts up on another cylinder replace coil assy.

do a compression test then do a combustion pressure test if all good computer is questionable

When cleaning your engine, water/degreaser went down the spark plug ports. Try using a air compressor blow gun to remove the moisture from around the spark plugs and boots. The water was causing the engine to misfire on 3 cylinders at first and as the ports started to evaporate the moisture, the less misfiring was occuring. Dry thouroughly and hopefully coils do not have damage to them. Also check to make sure the boot is making good contact with the spark plug.

Hello I need a help.
I have 1999 lincoln town car 4.6L V8.They have check engine light on. P 0303 cylinder 3 missfire.
I was changed spark plugs,fuel filter. check compression test 150psi. fuel pressuer 50.
swiching cylinder 1 to 3 fuel injector and coil. but they still have engine code

Cylinder number 5 is misfiring. Check spark plug, spark plug wire and ignition coil for the number 5 cylinder. The number 5 cylinder is the closest to the front of the car on the drivers side. With engine running in dark (at night) take a spray bottle of water and lightly mist spark plug wires and coil and look for arcing. Autozone will test coil for free.