Non Mustang Ford COP Engine Issue?

[Isaac-1]

My mother has a Lincoln LS V8 with Coil on Plug ignition similar to our 99+ 4.6 mustangs. The car currently has abogut 50,000 miles on it, over the last year she has had repeated problems with the engine runnning rough, SES light on detecting missfires always on cylinder #3 (also excessive cranking to get car to start, but only in the middle of the after initial warm up). The dealer has changed out the Coil on Plug and spark plug 4 times now, each time the problem comes back, sometimes after a few weeks other times in only a couple of days. Does anyone have any idea what else may be causing this problem, the dealership is not much help they are 50 miles away, and all they say is bring it back in and we will look at it again.

Thanks Ike

 

[Superhereaux]

if it's always on cyl #3 and you've tried a new cop and plugs i'd suspect the injector next, the whole long cranking would suggest a fuel problem as well

if you can swap injectors do it and see if the misfire follows

 

[chuck943]

if it's always on cyl #3 and you've tried a new cop and plugs i'd suspect the injector next, the whole long cranking would suggest a fuel problem as well

if you can swap injectors do it and see if the misfire follows

I believe you are dead on with that.

Have seen several of these. You could try just lifting the whole rail on that bank leaving injectors in rail cycle key a couple of times to pressure the rail and see if that injector is dripping fuel first, if it isn't dripping fuel then try and swapping them around.

 

[bdcardinal]

this is so common on the LS 3.9L motors. at my dealer we usually keep 8 of those coils in stock.

 

[Mustang5L5]

Swap the COP's around and see if it moves the misfire to another cylinder