This is the giveaway and it has absolutely nothing to do with the plugs.

Change the plugs if their ready for maintenance, but that alone won't fix this problem.

 

Yes it can - for a while, as I already said. Cops have to work a lot harder to fire across a larger gap. Marginal cops may keep working for a while longer, till the new plugs start to wear. I'm going by what Bluegrass has previously posted, and I trust his opinions.

 

Alright, he can do it twice if he elects to. But I 100% guarantee if he changes the plugs and leaves the coils, he'll have the same problem. Mark my words.

 

No doubt - it's just a question of WHEN.

 

10 miles max, - after a fresh re-boot.

 

I got new cops and plugs just to be on the safe side. The plugs are NOT original (thank god!) but I will still probably need to spray some WD-40 to loosen them up a bit so I won't break anything on the way out. Not sure about the cops, though. They were Motorcraft and the tops looked pretty worn so they may be original. 192k on original cops anyone?!

Again, guys - I really appreciate all of your help. I was completely lost after spending, probably, 6 hours on the truck trying to figure out where the vacuum leak was coming from. If(when) this works I'll buy ya'll an e-beer - haha.

Eric

 

combsatl, please tell me if this works out, my truck dose the exact same thing!!! i wasted so much time trying to find out what causeing this and i was reading this threat and sound just like my problem, please tell me if this works out!!! PLS!

exept i have 250+miles on 98 4x4 5.4L

ps. i dont have anycheck engine light

thanks...

 

As soon as I get them installed I'll update the post. One other thing I'd check for is go through your engine and check for any dry-rotted hoses. You'll probably see a few leading to the EGR valve (the thing that looks like the Seattle space needle) and also you'll see a bunch of dry-rotted elbow joints and hoses on the PCV system.

If you see them, go to Advance and pick up some 1/4" hose and replace. You can actually get the whole PCV system from Ford for $38. While you're at advance, pick up a few cans of Gumout carb cleaner and some electrical component cleaner. Use the carb cleaner to extensively clean your intake (mine was NAAAASTY - I sprayed probably 2.5 cans down it) and use the electrical cleaner to clean your MAF.

Even though my main problem hasn't gone away, I've noticed a HUGE increase in gas milage since fixing all the vacuum leaks. I was getting around 10mpg and now I'm getting around 14mpg with a mix of city and hwy driving - pretty impressive.

I'll update as soon as my COPs arrive.

 

Yea, I jumped up to 16 mpg after my last plug change, using Denso's. That's City and Highway tho. It's never been that good in the city, but I updated coils AND O2 sensors at the same time. Spit shined the MAF as well. Oh, and I re-ported and polished + port matched the intakes before I put it back together the last time.

Make sure you grease those coils correctly. That's where people screw up the most. Use dielectric on plug ceramics before install .

 

You shouldn't spray carb cleaner down the intake. Remove the throttle body to clean it, that's the right way.

 

ok thanks and i'll will do thos changes to the hose and my MAP is only couple months old, hope you finish soon

 

I thought it time to replace my plugs and COP's since I now have 67,000 miles on my 1999 F-250 5.4. I read all the horror stories about changing the plugs and elected to have a mechanic (that I have known for the past 10+ years) do the job. I purchased the correct motorcraft plugs and ordered the COP's from Global. He installed everything and also changed the fuel filter. Apparently, I failed to do that in the past - oops. Anyway he said the truck runs great. I picked it up and within the first week I noticed a hesitation while at idle or when accelerating at low rpm. Skip/Bump I think another post has listed. Anyway, I told my mechanic about it and he asked me to bring it back. He pulled all the plugs and they look great. He bought new plugs and it did not help. He put in all the original COP's and that did not correct the problem and now he and I are looking for help.

 

so ur telling me its not the COPS? damn im so streesed trying 2 find the problem!!!!

 

Pull the throttle body and clean it.

 

COPs arrived today. What special do I need to grease the coils properly?

Thanks,

Eric