02 Lincoln LS 3.9 V8 Misfire - Please Help!

[jdpowers]

I have a 2002 lincoln ls 3.9 v8. It has been misfiring in cylinder 4, and before that in cylinder 8. I found a good amount of oil in the plug wells in cylinders 7, 8 and 4. I changed out the valve cover gaskets on both banks as well as the plugs and ignition coils. I am still misfiring after all of that. If I put my car in park and rev the engine, every single time the RPM's hit 3000, the car starts continuously misfiring. In addition to this, when the engine load is high, and the RPM's are low (1500-2000) the car will misfire - almost like the car has hiccups.

I am just lost at this point, I know it could be a vacuum issue, or the cat is backed up, fuel injectors, or even O2 sensors. Any help would be much appreciated...

 

[RigsLS]

It's actually meant to misfire while in park or neutral @ 3000 RPM, it's a rev limiter.

It's listed in your OM (owners Manual) if I'm not mistaken.

http://www.lincolnvscadillac.com/tech/Lincoln-LS/2002LincolnLS-OwnersManual.pdf

 

[joegr]

As was said, you're hitting the neutral limiter, and on gen I it misfires on purpose when that happens.

As for the other misfires, you're no exception. Change all of the COPs, use Motorcraft coils, replace all the spark plugs (NGK would be good), verify all plug gaps are 1mm, no more no less, and check that all the coil and all the injector connectors are fully seated and locked in.

 

[cammerfe]

Joe just gave a perfect answer!

KS