I know these situations have been posted before, but I'm hoping for some more specific help. Truck is a 2000 F150 4.6. The other day it started running really rough and obviously misfiring. It would kind of come and go. I thought maybe it was bad gas or the cold weather, but I let it sit for a while. Drove it today and it was still bad, then on my way home from work it got way worse. It finally threw a couple of codes. P0302 and P0303, misfire on cylinders 2 and 3. Can somebody give me some help on diagnosing the cause? I'm going to check the COPs this weekend when I get time and see if there's anything obvious going on. Thanks in advance for any help.

 

How long since the plugs were changed? If it's been awhile probably wouldn't hurt to change those also.

 

Well, I know for sure they were changed about 30,000 miles ago, but this is a replacement engine and I'm pretty sure my mechanic put in new plugs when he installed the engine in May. I went out and did a visual inspection of the coils and they all seemed fine except for #1 which seems loose, but it's not misfiring that I know of. I will pull the 2 plugs this weekend when I pull the coils on the 2 cylinders that are coding. The coils are original for the truck and have about 136,000 miles on them. When the engine was swapped we just swapped the long block and kept the intake and all the goodies from the old engine because they were still good. I'm hoping it's not a coolant leak... I already went through that headache with the last engine.

 

I was also thinking of swapping the coils over and clearing the codes to see if the codes followed the coils. Good idea?

 

If your coils are original at 136k... I would change them all and call it a day. Also, it sounds like you don't know if your plugs were changed with the swap, and if they were, what plugs were used. There are many plugs that most mechanics would otherwise look past that just don't work with these engines. Also, there is no real visual inspection you can do to determine a misfire. Of coarse if a boot was torn or something like that then yea, otherwise... not much you can do other than simply replace them.

 

Well, I haven't really had time to do anything with the truck with having no garage and a crappy gravel driveway, not to mention being low on cash. I did, however, go ahead and order 2 replacement coils. I wanted to get a full set, I just can't afford it right now. Figure if I can buy a couple each paycheck then I can have them all replaced soon enough. What I was able to do is go out Saturday and see if the truck would start. Fires right up and on all cylinders, too. Revved the engine a few good times with no problems, so I'm definitely thinking the coils are bad. The misfire didn't usually start until after it was warmed up, so would I be correct in assuming that the coils are probably getting hot and causing the trouble? That's my best guess and I'm hoping the new ones fix the issue. I will report back when I have the new coils installed.

 

...

 

Well, I got out there today. I'm a little concerned now. Checked the oil while I was working on it. The bottom of the oil cap was absolutely slathered in thick, creamy oil. That scared me to death, although I know some is normal during the winter and I'm pretty sure my PCV valve needs replacing. I got a little relief when I check the dipstick and the oil is showing exactly full and looks great and also smells of oil and not coolant. However, when I was pulling the coils out, I noticed quite a bit of moisture on the boot of cylinder 2. Not quite as much on cylinder 3, but still moisture. No signs of leaks from the heater hoses, but it looks like there may be some near the intake manifold gasket. I'm thinking that my issue is a small leak there. I put in the new coils and drove the truck around the block and I think I still noticed a slight misfire, but it could be my imagination. And what I was talking about with the loose coil is that #1 isn't tightened all the way down and won't. Mis-threaded evidently. I know that #5 was misthreaded because the Ford dealership that serviced the truck at 100k put a spacer in it so it would tighten correctly. At any rate, I'm going to drive the truck to work tomorrow and see what happens.

 

The gunk on the cap really isnt cause for concern its very normal. I've never heard of an intake leak unless its super bad, getting coolent in the plug holes. Probably water from the road or maybe your cowl gasket is bad. I'd do something about that loose coil bolt that can cause the coil to fail or worse a plug blow out.

 

There were a few other things I had planned on doing soon, so I figure I'll just go ahead and knock them all out. Going to pick up a set of Motorcraft plugs, new thermostat, new heater hoses, new PCV valve, and an intake manifold gasket set. I've also got a replacement thermostat housing that I've been meaning to replace but I've kept putting it off because the quiksteel I used to patch the old one has actually help up and I haven't felt like messing with it. I figure after only about $200 I should have it going pretty good again.... I hope. BTW, anybody know where I can get replacement bolts for the thermostat housing? I've got one that is all buggered up.

 

Started tearing into it today. Got the coolant drained, air intake plastic off, alternator removed, a few vacuum lines off, disconnected the throttle cables, and started on the EGR valve. The front bolt is being stubborn, so I soaked it with PB Blaster and called it a night. Getting dark and cold anyway. Hopefully tomorrow after work I'll have the intake off if I'm lucky. Once I got the alternator off I looked down under the intake and noticed quite a bit of moisture where the intake meets the head. It's not leaking so bad that it's running all over the place because everything was pretty dry under there, but I guess it's just building up and running down into the plug wells. Got the gasket ordered and the rest of the parts I'll pick up this weekend and hopefully have it finished Sunday if the weather holds out. Wish me luck. No doubt I'll need all I can get.

 

Also, I didn't bother driving the truck to work. I figured I'd just do all this work to it and hopefully be done with it... for now.

 

Worked on it some more this afternoon after work. Got the throttle body off and all the electrical connections disconnected from the COPs and injectors. Few questions: What type of fuel line disconnect tool do I need to disconnect the lines? Just a standard one? I used to have a set of small plastic ones, but I've lost them somewhere along the way. Also, it appears that I can just pull the intake with the fuel lines and injectors still mounted to the intake. Is this correct? Would make it a whole lot easier. I swear I think the engine got bigger... or the compartment shrank. And is it possible to pull the intake with the EGR still attached to the exhaust line? I can't seem to get anything in there to get it loose. Last question, what's an easy way to clean the EGR ports in the throttle body? One of the ports at the bottom is completely clogged with built up carbon. The rest of the throttle body looked pretty good. I can take pictures if I need to to show anyone what I'm talking about.

 

How did you get that stubborn EGR bolt out. I am in the same boat here and that thing is stuck in there. Tinking about heat but afraid of cracking the cast alum. housing.

 

No worries you won't. Dissimilar's aluminum/steel corrosion breakdown occurs at about 350 -400 degrees which isn't much more than a hot solder gun. SO, -just use a little propane and it will SNAP free. It may even sound like it broke - Nope! It broke free is all.

Now what you don't want to do is point that torch in the direction of the EGR diaphragm just under the top of the saucer piece at the valve itself. You'll fry it right up in about 2 seconds.