Ignition Mis-Fire problem

[03Mach1]

Vehicle: 2003 Explorer 2wd 4.0 auto ~ 80k mi.

Drove the X last night and everything was acting normal. Started the X up this morning and it felt rough, I figured maybe it was just because it was like 40deg outside and this was just a typical rough cold start and after it warmed up a bit it would go away.

I let it idle for a few, still acting rough, before I decided to pull off and see if it would warm up and settle down. Pulled out the driveway and got about 1 block away when the CEL came on so I turned around and came back home.

Got it in the driveway and shut it down, then re-started it. Once re-started it still felt rough but no CEL at first. Truck ran for about 2 min before the CEL came back on.


Popped the hood and had someone start the truck and the motor was rocking which accounted for it feeling rough, thinking maybe somehow something went wrong inside the engine(spun bearing or something) I was pretty irritated so I figured I better check the codes first before throwing a fit. So I pulled out the OBD II reader and got PO300, PO301, and PO302 - Random mis-fire, Mis-fire cylinder 1, Mis-fire cylinder 2.

I have been searching for over 2 hours trying to figure out how to check the coil pack. I understand checking the primary ohms and secondary ohms but my Haynes manual has no info on the specs or how to test it. I have found diagrams online but I see all different info on what the readings are supposed to be. If anyone has this info it would be very helpful.

Plugs and wires were both replaced within the last year or so, when replaced nothing was wrong but I think the truck was at like 65k or something so I just replaced the plugs, wires and fuel filter when I was doing an oil change.

I also find it hard to believe that 2 plugs or 2 wires would go bad at the same time which is why I am suspecting the coil. The only thing that has me worried is that it is cyl 1 and 2 rather than 1 and 5 or 2 and 6 which operate off the same coil. So in essence I have 1 of 2 coils working and 1 of 2 not working on two seperate coils if that makes sense.

 

[03Mach1]

And so the saga continues. When it rains it pours.

So I decided to bite the bullet and replace the coil pack. Got it put in and re-started the truck. Vibration seemed to go away for the most part. Since I disconnected the battery during the R&R the codes that I was getting were wiped out. Let it idle to operating temp in the driveway and no CEL. From watching and listening to the motor I could tell there was still a mis-fire but seemed like it was not nearly as bad as before. I could hear the "connecting rod pulling the piston noise" every now and then as well as see the slight shudder which meant mis-fire.

While R&R the coil pack I pulled the #1 and #2 plug to see what they looked like and they seemed ok. While looking I noticed on on the back end of the passenger side valve cover there was oil. I figured well the truck has 80k on it so for there to be a small oil leak is probably par for the course and since I am not loosing any signifigant amount of oil between changes I blew it off for the time being and figured I will just replace the gasket at a later date.

Once the truck was up to operating temp, still no CEL, I figured I needed to get it moving and under load to see how it acted. Well drove it for about 10 min going from anywhere from a stop up to about 60 and the problems became more complicated and more confusing.

When I got to the first stop the car shuddered and almost felt like it was going to die for a second. Then there is a clicking noise, goes a noise every few seconds to a repetative noise for a few seconds, then to no noise at all. Does this constantly. The noise does not match with the speed of the vehicle nor the RPM's just here and gone in varrying levels of volume and repetativeness. Still no CEL light.

Got to a red light and noticed slight smoke coming from under the hood. Turned around and drove home popped the hood and noticed the smoke was coming from the passenger side header. It was being caused by that oil leak I spotted earlier on the rear of the passenger valve cover. Seeing as this has never happened before(the smoke) I am assuming that leak was never there until this morning. So still no CEL. The leak must be pretty decent seeing as within 10 min of parking it I had a fresh puddle about 4" round. I got in there with a rag and wiped it clean and did not see a new flow so its hard to tell where it is coming from. It still mis-fires but not nearly as bad as it was when the CEL came on earlier this morning so I am clueless at this point.

I guess its time for a trip to the dealer

Just what one wants around Christmas time.

Probably won't be able to get it there until Monday or Tuesday so if anyone has any suggestions or things I should check out I am all ears.

 

[swetrid]

The rear timing chain cassete has probably broken causing the misfires. The guide breaks apart and then gets jammed in valve cover or chain wears through the valve cover causing the leak.

 

[OneLever]

I did a little forum search to get the ball rolling for you.

From what I found I'd say STOP RUNNING THAT MOTOR! Get a shop manual and take off the valve cover to look at the issue. Or take it to the dealership who will probably tell you you need a new engine...

Here is the main link that got me worried for you: Link
You can find many similar results using the forum search "03 valve cover".

 

[03Mach1]

I figured as much as far as stop running it. Thanks for the help with the search. I probably came up dry because I was looking fir the PO300 ect. Codes and didn't notice the oil till later on. I might try to pull the valve cover tomorrow and see what I come up with. While I am worried about the chains/tensioner setup the only thing that makes me hopefull is that if there was enough slack in the chain it would gave jumped a tooth and the motor would not be running as smooth as it does at anything above 1k rpm. I looked again and did not see any hole in the valve cover so I know the chain didn't wear through it. Also since I wiped it the oil is not leaking but that's just becasuse it's not running so no oil pressure.

Not sure what to as of now. I know a trip to the dealership is in my future as I don't have the time to pull it all apart.

I think I might pull a valve cover and look at a few other things just incase it's not the chain setup. I know I had to deal with the chains when I swapped motors out in my 01 GT so I am not unfamiliar with working with them. Wish this was a V8 as the chains are all on the front and don't require a motor pull.

 

[OneLever]

There are a bunch of threads on the forum about replacing the chain and guides yourself. But it looks like a fairly involved job that will take a few days of dedicated work. Definitely take a look at it and post some clear photos on here.

You can at least research those threads to find out what a fair dealership charge should be. They will likely try to make it out a catastrophe even if it can be salvaged. If you wanted to be really smart you could essentially figure out what the job is exactly, parts and all, and have them charge you for labor only. Walk in with the parts and have them install them.

 

[03Mach1]

Well I got back into it this morning. I was considering pulling the valve cover off to see what things looked like under there. Was hopefull that maybe just a lash adjuster failed and possibly kicked out one of the rockers.

I decided to feel around the valve cover in the back corner to see if there was possibly a hole that was on the fire wall side of the cover which is why I didn't see it. Well there was no hole but after running my finger across the area there is a crack in the cover. The crack goes from the top of the cover on the back outside corner all the way down to where the rear corner bolt is.

Here are my thoughts, an outside perspective would be greatly appreciated.

My choices are:
Pull the valve cover and have a look around. There may be nothing wrong with the chains or the guides but seeing as the crack is right where the chain is I find it highly unlikely.

There is a place about a mile from me that will put a remanufactured engine into the car. I e-mailed them so I am hoping to have a quote on that in the morning. The plus to this is not having to wrench on it myself and the re-manufactured motor can have up to a 3 year warranty on it. Downside is going to be cost. I am going to guess a minimum of $2500.

Last option would be to do the repair myself. I really don't want to pull the motor out though. I was wondering if this repair can be done by removing the tranny. It would be tight quarters but it might be faster than pulling the motor.

My worry about replacing it at home is that if a part broke, there is a pretty good chance that there is a piece of it in the oil supply. I would hate to go through the time and trouble fixing it only to get it back together and have the piece work its way into the oil pump or something and destroying the engine. Anyone know if there is any kind of screen on the oil pump pick up?

 

[OneLever]

My choices are:
Pull the valve cover and have a look around.

I wouldn't buy any parts or new engines until you take off the valve cover and look at the damage. Do you have another form of transportation?

I was wondering if this repair can be done by removing the tranny...there is a pretty good chance that there is a piece of it in the oil supply...any kind of screen on the oil pump pick up?

I can't see how this job can be done without pulling the engine out. There is a decent chance that bits of plastic fell into the oil pan. However, with the engine out it is easy to get the pan off and clean it up. There should be a screen on the oil pump pick up.

 

[03Mach1]

I probably will take the valve cover off just to see what things look like.

As for another vehicle to drive I am setting up a rental this morning.

Whats killing me is time. With the holidays here there is alot of other things that require my time so time is at a premium right now.

Here is what I am worried about. Lets just assume it was the rear chain for now.

I spend my time to pull the motor and get everything apart. Once out of the car I start digging into it and find that there is a bent valve or something like that. If the valve is bent then there should be a matching mark in the piston. Now I have to figure out how to locate and have a new head shipped or find a shop that can fix the head. What do I do about the piston? Shouldn't something be done about the knick that the valve caused?

I wonder if I pulled the cover if I would be able to tell if there is a bent valve in there before I pull it apart?

 

[03Mach1]

I guess the next thing to consider is what is the cost of all of the replacement gaskets as well as the parts needed to replace the guides. Also since the motor is out I might as well replace the ones on the front too while I am in there right.

I got a quote this morning for $4,100 for a re-man installed with 3yr / 100k mi warranty on parts and labor or $2,900 for a used motor no warranty. Both prices include labor.

 

[OneLever]

I wonder if I pulled the cover if I would be able to tell if there is a bent valve in there before I pull it apart?

The only way to check that I can think of is to perform a compression test. But then the question is: Is it ok to bump the engine a few times to do this? My personal, non-professional, opinion is that if you were having valve to piston contact there would have been noticeable noise from this.

I guess the next thing to consider is what is the cost of all of the replacement gaskets as well as the parts needed to replace the guides.

I don't have that information but some of the threads you can find on the forum might.

Also since the motor is out I might as well replace the ones on the front too while I am in there right.

That sounds prudent.

 

[03Mach1]

Well I drained the oil and so far all I found is some small coils of black plastic. I am getting ready to remove the lower part of the oil pan and see what's in there. I thought the tensioners were orangish plastic so now I am wondering what could create little coils of black plastic??

 

[03Mach1]

Pulled the bottom part of the oil pan out. Found pieces of the orangeish plastic that the chain guides are made of.

All in all the pieces I found probably would not cover the surface of a quarter.

I called the Ford dealership and they are quoting me $1700 labor plus parts to replace all of the chain guides and tensioners. He said after parts and tax I would probably be looking at right under $2,500. Anyone know if this is reasonable.

I am considering it but the one fear I am having is this all started with cylinder mis-fire codes so I am thinking the chain jumped and the timming is off which possibhly caused piston/valve contact.

 

[OneLever]

It sounds like you don't want to do the work yourself. Out of the options you've listed the dealership is the cheapest. Which would be on an engine who's history you know. What is the warranty on their work?

$4,100 for a re-man installed with 3yr / 100k mi warranty

$2,900 for a used motor no warranty

...right under $2,500

You can ask them if the $2,500 includes pulling the heads and inspecting them for damage. I'm guessing it does not.

 

[03Mach1]

It sounds like you don't want to do the work yourself. Out of the options you've listed the dealership is the cheapest. Which would be on an engine who's history you know. What is the warranty on their work?



You can ask them if the $2,500 includes pulling the heads and inspecting them for damage. I'm guessing it does not.

Truth be told I really don't know the history on the existing motor. I bought the truck used in 08 with about 54k or so on the clock already.

I am capable of doing the work and have the needed equipment but with the limited amount of free time I have right now I think the only option will be to have someone else do the work. Sucks as I would prefer to keep the labor money in my pocket but I can't drag this out for 2 weeks by working on it when I can.

The dealer price was an over the phone conversation. I did mention to the service guy that I was worried about valve/piston contact and he said they would check that out and that if the head needed to be re-worked that would be in addition to the $2500. So while the cheapest up front it does have the potential to be more expensive. If the head needs to be re-worked or possibly replaced the cost could easily come close to a re-man enigne.

The shop that will replace the motor has been in business for over 45 years so I do trust that they are not just going to run to the junk yard and find a replacement engine and stick it in the X. People I know have either heard of or dealt with the shop and none have anything bad to say about them.

I really don't plan on keeping the X for very long after it is fixed 6-8 months max so spending the $4100 for a re-man is pointless when I compare what I have into the truck vs. what I can get out of it when I decide to sell or trade it.