Cly4 Missfire Cracked plugs

[rsilva708]

I have a cly 4 misfire problem. It happens every 4000 - 6000 miles, and my explorer will start to miss, and then throw a cly 4 mis code. When I pull the plug it will always have a hairline crack. Change the plug and the problem is gone till another 4000-6000 miles. I have included pics of the last two plugs I have changed. The plugs are Autolite APP 103 Double plat.

2000 XLT 4.0 OHV

 

[jfman]

Old dog's trick:

Remove the injector from that cylinder and exchange it with another one on the truck. If the problem migrated with the injector, then you will know it's that injectors fault.


Might not be this but I would try it, wont cost a thing.


I dont know if you have coil on plugs but if you do , you can try that same technique with the COP.

 

[Josh]

Just curious how the injector would cause this problem?

 

[jfman]

Just curious how the injector would cause this problem?

Clogged/bad injector. Bad fuel delivery, detonation, lotsa heath, cracked plug.

 

[Turdle]

Clogged/bad injector. Bad fuel delivery, detonation, lotsa heath, cracked plug.

Something is making that cylinder run hot, I agree

Intake leak? Carbon buildup raising compression?
Dirty injector?

See the red color--doesn't that indicate a lean burn sometimes?

 

[Brandons]

Thought id look in the haynes book for spark plug conditions, closest one is detonation (reffering to the crack in the insulator). Did you check the other plugs to see if they have the crack in them as well? This is probably pretty pointless to post but i heard detonation mentioned earler in this thread.

 

[exploded99]

I don't think that tip looks too bad. On either the Motorcraft plug site or the Bosch plug site I read that the reddish hue is from gas additives - you might look at the pictures of tips there.

Is the grayish/whitish stuff on the threads at the end of the plug anti-seize compound?

Is there any evidence on the upper portion of the plug it has been getting wet?. Are you losing / using coolant?

 

[rsilva708]

I don't think that tip looks too bad. On either the Motorcraft plug site or the Bosch plug site I read that the reddish hue is from gas additives - you might look at the pictures of tips there.

Is the grayish/whitish stuff on the threads at the end of the plug anti-seize compound?

Is there any evidence on the upper portion of the plug it has been getting wet?. Are you losing / using coolant?

The grey stuff on the threads is not anti sieze. I used it when I changed the plugs after I first bought it, bit since I know I will change the plug almost every other oil change I haven't been putting it on.

As far as fuel additives, are you talking about what additives come out of the pump, because I haven't added anything.

It did seem like I did loose a bit of coolant, that I didn't notice leaking out, but not much.


Also, for a little history, I bought the Ex in Jan 05, and it had a leaking headgasked that I found a week after I bought it. I brought it back, and new gaskets were put in under warranty.

 

[exploded99]

Yes, the reddish color is from fuel additives normally found in unleaded gas. I meant to say I found out about that on the AUTOLITE website. Go to autolite.com, click on car care, scroll down to plug tip diagnosis, and take a look at plug 2.

I would pull the plug from another cylinder for comparison. I think you will find the following:

1. The plug from the other cylinder will not have the grayish stuff on the end of the threads.

2. The tip will look about the same color, but of course no cracking. That would suggest your injector is working ok - . Except for the crack, I would look at that plug tip and say everything looks fine.


Dunno - I am guessing there is a problem with the head or the head gasket based on the gray stuff on the threads. Detonation will crack a tip like that, but I would expect it to happen much more frequently - once a cylinder starts detonating it is usually from a pretty serious problem, and it keeps doing it. Do you have any pinging from the engine?

If you are under warranty, take it back and have them look at that plug. If not, I guess you will get to keep changing plugs. Unless you want to pull the head.

A wild guess, aka a WAG, take a close look at the #4 plug hole with a bright lite and see if it has been helicoiled. If someone stripped the threads in that plug hole, they may have drilled it out and helicoiled it.

Maybe somebody else can come up with something?

 

[Brandons]

Well i decided after reading this to check my spark plugs, and heres one of them.

No description in haynes for it... Well the closest one i can think of is TOO HOT...

 

[Turdle]

Fuel mixture too lean brandon
Intake leak?

 

[rsilva708]

First off, thanks for all the help so far.

As as asked above, I checked the #4 plug hole, and it does not appear to habe been helicoiled.

I also pulled out #4 again to see how it looked after about a week. No cracks yet, but it was wet. It was hard to tell what the wettness was, coolant,oil,fuel, but it was wet. when I pulled the #6, it was dry.

I also pulled the #6 plug to compare to. It is the same type APP103 Double Plat, that has been in for about 20K. It looks like it is in much better shape than all the plugs that come out of #4

Pics Below

Side by side with one of the damaged ones

 

[Turdle]

That is one hot cylinder
Fuel injector?

 

[rsilva708]

I don't know if it's an injector, coolant leak, or combo. As exploded99 said above, there is a lot of crud on that plug. exploded99, what do you think, a collant leak?

 

[shamaal]

As a suggestion,
A compression test may be illuminating. It will give an indication of the health of the cylinder. If within family, it would point towards the injector.

 

[jfman]

this is not good buddy.


I would defenetly do a compression check. (have you tried swapping the injetor for one cyl to another ?)

GOood pics btw

 

[rsilva708]

this is not good buddy.


I would defenetly do a compression check. (have you tried swapping the injetor for one cyl to another ?)

GOood pics btw

I have not tried swapping the injectors around yet. The way it looks, I would have to do a lot of work to get to the inkectors, and if I'm going to do that much work to get to them, I might as well spend the $40 for a new injector so I wouldn't have to go back in again to replace it if it is bad.

I will see if I can get my friends compresion tester and check it out. Would it also help to tell if I'm loosing coolant into the clynder by doing a pressure test on the coolant system?

They say a picture is worth a thousand words. It is easier to show everyone than try and explain what they look like.

 

[jfman]

Would it also help to tell if I'm loosing coolant into the clynder by doing a pressure test on the coolant system?

.

If the compression IS lower than it should then you will know its a mecanical problem that is contaminating the plug ie: bad piston rings

 

[rsilva708]

If the compression IS lower than it should then you will know its a mecanical problem that is contaminating the plug ie: bad piston rings

Is there a standard compression range I should expect to get on a 2000 4.0 OHV

 

[budwich]

sorry I haven't looked it up but where is cylinder 4.... by any chance its on the passenger side in the middle (ie. another cylinder on both sides).

forget it, I see that it on the front driver's side....