99 expedition 5.4 random cylinder missfire also cylinder 4 missfire codes

[expo dude]

i went and degrease the engine after that had rough idle for half a day now i have an internment misfire at times while driving it will start to miss fire it has been a month since i have degrease the engine any ideas would be helpful less than a year ago i have done a complete tune up on it with new plugs and wire links. it had the coil over the plug system.

 

[splintrcel]

There is probably degreaser in the spark plug hole. If the boots are original they stop sealing correctly after awhile. Just pop the COP out and blow out the hole. Also do you have a rear aux heat? There is a split in the coolant lines to provide coolant to the rear unit. At the T connection it likes to leak from corrosion over time. This usually causes Cyl. 4 to misfire because the connectors sit right above the COP.

 

[expo dude]

it does have rear hear and air also the tune up was done less than a year ago with new plugs and new plug boots.

 

[splintrcel]

Check to see if your leaking coolant then out of those connectors and also check the COPs again. Depending on what brand you went with some just fail at random. You can use a multimeter and check the resistance of the coil. They should all have relatively the same resistance.

 

[expo dude]

most of the cop's are original equipment on this truck they still state there motorcraft while i check resistance where would i do that at?

 

[splintrcel]

One probe needs to be on the spring and the other goes on one of the contacts that attaches to the wiring harness for the ignition. It sounds to me though that its most likely the faulty T connector but thats the fun with a misfire, It could be like 50 things it seems.

 

[expo dude]

that t connector you talk about would you be talking about the harness connector of that coil

 

[expo dude]

also wanted to ad when i first start the truck and drive its fine when it warms up a bit is when i get the problem of misfire. and its not all the time its random.

 

[bedrck46]

Advance auto sells just the boots alone Autolite Boots