This is on my dads 99 explorer 4.0L sohc is getting this code. He came down this weekend to visit and said he had it in the shop most of last week. Said they changed out the spark plugs and the MAF sensor. Me said that it ran good for the first 15 miles then it started spuddering and lost power. I looked at it when me got here, pulled the # 5 and 6 plugs to see if they were getting fauled? and they still look brand new. so we went to auto zone to have the codes read. They said that cyilnder #1 had a miss fire. Checked the plug wire and it was loose , put it back on and disconected the battery to clear the code. It seemed to run goodfor the first 12 miles down the road then when we stoped to turn it started to spudder again. Any Help would be great.

 

pull the spark plug out if it has anitfreeze on it, you need to get it to a shop and have some gaskets replaced before you buy a new motor. Had number 4 misfiring and i noticed plug wet blew out the hole and replaced. Truck ran good for few months until it blew

 

Sounds more like the plug wire isn't staying seated on the plug (or the coil).

Find out what brand of plugs and wires were used by the shop, they might have been el-cheapos with inferior or wrong fitment.

If they were correct, perhaps the wire plug connector needs tightening to get a better grip in the plug. A pair of pliers will usually tignten things up if they are, in fact, loose.

Steve

 

As far as the plugs go they were autolite. The wires didn't get changed he said but were checked? how I don't know. my dad said driving it this week it would run great one day and like $h!t the next. He took it back to the shop to have this guy look at it again. They put new O-rings on the intake thinking that it mite be a vacume leak. tested the injectors, pulled off the plug wires one at a time to see if it run any worse with diffrant cylinders down. Installed new O2 sensers {has 108k and still oem}
Would the EGR make it run like crap one day and not the other? My dad lives 2 hours away so I can't look it over to try any thing out. There comming down this weekend if it runs ok there going to bring it. so i'll have a little time to look at it.
One more thing. When the coil pack goes bad could it drop cylinders every now and then or do they allways just quit.

 

I recently had a coil on plug (COP) go bad. Your dad has a 4.0 while I have a 5.4, and I know that COPs and coil packs are not the same, but they do perform the same function.

When the COP went bad it might start up and run fine. Then I might start it up 5 minutes later and it would run like crap. Also I would start it up, drive a while with it running bad and then all the sudden it would run fine.


So yes, I think when they go bad they work intermittently.

 

ended up being the #1 injector was bad. Changed it out and it runs great.