I have a 2005 FX4 SC with the 5.4. I have an ongoing problem when at high speed (does it when empty, worse when towing or loaded) the engine bucks or stumbles. It only seems to do it when on the road for a long period at high speed. I had it checked at the dealer and they diagnosed a # 5 cyl. spark plug fouling due to a bad injector. It did not fix the problem. The problem seemed to start after I installed a K&N filter, but has continued since I installed a Volant CAI. I am going to clean the MAF with CRC MAF cleaner when I get home, but I am wondering if anyone has any other ideas. Thanks.
Happy New Year to all!

 

What are you thinking - maybe some oil from the K&N contaminated the MAF ? Sounds like it. Something to check.

 

Some 04 and later engines go lean when the intake track is altered.
If you can't find the cause, go back to OEM stock intake tract for a trial test.
I would test the fuel pressure for being close to spec and a fuel filter change if it's time.

 

my .02... all my stumbling problems on my 4.6 (i know its not the same motor yadda yadda) was from bad plugs and wires. once i had this problem from a cracked plug porcelain, really freaking hard to see too.

 

I can't beleive this, but mines doing the same thing - it started on the way home this morning. I drove it again tonight about 40 miles on the e-way , It would still hold 80mph on cruise and buck every so often.

On the way back home I got off the exit just before mine and then got right back on. I poored the coals to her tho - That's all it took , now I got a blinking light (MIL) + misfire. I will get it read in the next couple of days at AutoZone to identify the cylinder that's acting up.

I've done this before - The only way I can get an engine light to come on is if I give it hell - If I stomp on it and I'll get a light to come on if it's a misfire prob.

I just replaced those COP's last spring , but my dielectric grease has wore off in spots and it's been raining here - I prolly got a coil wet and it shorted out ..

If I were you I would replace coil 5 - or buy the whole COP kit on eBay if you have allot of miles on yours - There cheap!

 

Update - took the truck just up the road and now the lights blinding me (on steady) I wiggled all the COPs around and checked to make sure they were plugged in. Geezz mosy of the dielectric grease I put on is gone!! I guess you have to keep on it .. It's a clasical mis-fire with mine.

Hope you get yours worked out - I 'm takeing mine to Auto Zone tommorow , I heard they stopped giving thr free readings there for some reason ?? Oh well - I may have to buy the tool - hope it's not to costly..

 

I have found that the dielectric grease does not last beyond about 500 miles or whatever heating takes place to change it to a semi hard state.
I have been chasing what felt like a low speed, light load intermittant miss and so far found it not to be plugs or coils.
Every so often there is a complete power drop out.
The next thing done was to swap the PCM relay with the trailer relay. So far the problem has not shown it'self and it's raining pretty good here now coming off a trip.
I learned a lot about plugs, boots and coils while chasing my problem.
Found a way to enhance the plug to boot insulation and the boot seal at the top for head seal against water intrusion.
One thing was, that the bad reputation Bosch plugs seems to enjoy is not justified as I am running those plugs (regular single plats) in lue of 2 new sets of Motorcrafts that was tried and seen the same missing. Much of the time it's not the plugs causing the problems.
At this time and for the duration of my problem, I can't pin the seeming miss, on coils either because it's not there for weeks at a time.
Hopefully the power drop out pointed to the relay as the problem causing low/ intermittant voltage to the PCM and affecting everything.

 

I can only imagine how much trouble shooting time it must have takin to come to that conclusion or even to try said experiamentation between the two relays.

So , from what I gather it could be the motorcraft plugs as well , but you can't be sure - it could of been the relay , correct?

Yes that grease dosen't last long. The opening in the weelwell is what I'm questioning . On the 4x4 there about a 10 inch gap exposing the manifold and it seems water could find it's way into the plug chambers in a heavy rain.

Did you make some sort of chamber insert out of heat resistent material that seals the chambers?

thanx

 

My problem never was a water intrusion. The missing action occurred under all conditions of temp, rain etc and as an intermittant low load rollon the throttle.
I have spent many months chasing this to the relay point because of the violent drop out that just took place. It becomes clear it was not really the ingition as a base fault after all. But this resulted in a lot of searching and trial testing.
There was nothing to point to the problem except to think hard what would cause the drop out. There was never any codes.
A power drop out could not set a code in any event.

As for plug seal enhancements, I am running 2 # 110 O rings on the plug insulators to take up the space between the boot and the plug body.
Old OEM boots enlarge their tips with age so the tight fit on the plug is lost.
At the top where the boot is supposed to seal in the head, I use a #10 O ring set in the top grooves. These numbers are industry standard ring #s.
All these should be well greased for the best chance of having everything slip on and seat with out hangup.
The plug rings will not interfere with a plug socket except possibly one that has an internal rubber guard.
I made a device to install the rings onto the plugs when they are already in the heads, otherwise the plugs need to be removed and put back in.
I think this ought to benfit the off roaders and others who have a water intrusion problem.

In addition; research has brought to light how this system can be improved in power tranfer efficiency but it cost some big bucks. Hot coils are not always the answer and makes faults like plug boots even more critical.
Reason is even with stock coils, when the plug can't fire, the spark has to go somewhere so guess where? Hot coils makes this even worse. Does things like sneak out from under the boot tip, thru the boot causing holes and even back at the coils causing them to fail and even sending trash back to the PCM upsetting it's operation and other engine control functions. A combination like this can create a tough time running it down because the engine can act in a lot of different ways until it gets sorted out.
Within the above is the reasons why Bosch plugs are not alway that bad but something else is causing the problems when it seems like the plugs are to blame.
Most know that Bosch makes OEM parts for Ford and many many other companies. There is no positive proof that I have yet to see 'WHY' this make is any worse than any other. They are all made using the same process as any other mfger. The electrode design may be different for alloy and shape but they still work just as well. Certainly a $2.75 plug is not meant to last 100,000 miles but be chaged at reasonable intervals to keep engine performance up. This is the only real difference between the low priced and the hi priced plugs, one of being extended life. It's a lot like the debate over oils. It's what is expected out of the service interval and where the owner stands on doing the service work
On OEM plugs, Ford has superceded the originals with a plug that has higher center resistance. This little fact can make a missing condition come even faster. It lowers power tranfer efficiency along with providing extra RFI protection. So it's not all good IMO.
The Bosch plugs I currently have running, have been slected to be like the originals that came out, for center resistance.
All these things came about in the search for the original problem.

 

Good info - I seen one guy so far that had boots for his coils lol , I didn't get a chance to talk to him - I wondered where he go them. Anyway , It's close to 10 years now with this COP system and that's great fix for sealing the chambers . Greasing that big gap between the head and the boot has the shortest life and is the first to get compromized.

Why did they change the stock boot design in 99? I always thought this might of had adverse effects. The inside of the stock boots on the 97 & 98 model years consisted of brass and copper and a thicker dense outer boot. Maybe you've seen these before ? As you know the newer design consits of a spring and a piece of steal (round stock lol in the center of it) If not I'll take pics of the two and post later today. All of the green stickerd COP's came with the older style boots. The pic below of the boot set up with the shorter springs actually say "Ford" on the boots and that brass piece that the short spring slides over is fastened to 18 guage copper wire that pretrudes out the other side 1/32 of an inch and comes in direct contact with the top of the plug. These seemed to be a better design , but a more costly one. MHO- this is why they may have been inlliminated.

That big gap in the wheelwell is needed for heat reasons , that's why I never sealed it off.

Interesting findings about the Bosch, ; that was a bit strange how Bosch can make so many componets in the automotive industry, but seem to fall below standerds with plugs. It's also very baffelling why Auto lites fail in my motor aswell - I compared and they look identical.

Well , I 've been looking for a way to test coils under a load without haveing to go to the dealer and found this below - never seen probes like these, do they load test? - it prolly just test spark.

I can see how those O-rings would work perfectly - great idea!! I need to install a new set of heater core hoses as well - so I'll purchase those O'rings while I'm at it. I ordred some original Ford clamps off eBay - just waiting for those to get here (they actually say "Ford" on them lol)

I found some other pics of the boots and compared the two -

 

The only true way to see what the total system is doing is via a scope display.
On that display you can see all the operating parts of the system.
Getting educated to the systems and being able to interpet the wave form parts tells you exactly what is happening. The ramp testing is all important.
On these waveforms you can see a coil with a slow rise time, internal 'fuzz', a plug that is leaking,fouled, by the high voltage spike height etc.
It's beyond most of us to have that kind of equipment so we have to tough it out by deduction and parts sub where the problem can't be pin pointed.
Reason I know about scopes and waveforms is my living was made in the electronics field but I still don't have that kind of equipment at home.
As a trouble shooter over the years, you become good at logic deduction when analysing the fault by how it acts but still can get fooled until each area is eliminated.
On my peticular fault, I ruled out the coils early because the fault was intermittant and low speed low load related. However the plug changes did seem to clear the problem for long periods of time and fooled me to a large degree. This is why I did the plug testing with all the side mods. It also seemed to prove the plugs are not the cause but did find that plugs themselves are not a great cause of problems by mfger. The BOSCH #6241 is a single fine embedded wire plat and works fine but is not close to being a 50,000 mile plug.
I do see that all plugs begin to 'burn down' both the tips and the ground in a relitivley short time increasing the gap originally set. This in it'self makes the plug harder to fire even in a short time. I install with a sleightly smaller gap to account for this errosion.
The times when the engine puts the most load on the plugs are after decelleration when the fuel goes lean and hard accelleration. Both conditions are totally different for the plug. These are usually called tranient operating conditions. In my fault, only one condition was present.
Any fuel additives that cause deposits on the plugs such as some octane improvers, will likely cause a missing condition at some point. One of the sensitve points for this would be during EGR operation when the combustion is very difficult due to exhaust gases mixed with the intake air and fuel is lean.
All in all there is a lot more to all this than the averge owner realizes when experiencing a drivability problem. The best senario is a fault code for the cylinder involved then it's easy.
One thing I would caution on, that is about moving a coil from cylinder to cylinder playing checkers. What I often see is after one does this to find a bad coil usually another coil goes bad. I think the reason why is as follows;
The original defective coil location could have lost the coil from a bad plug or boot or even moisture. Moving another coil to that cylinder can lose another coil when the problem is not really the coil as the root cause. So the expense and frustration mount up. The reason the coils can get lost is the PCM drives the coils no matter what the conditions are with the plug and boot. The hi-voltage has to discharge and is hard on insulation breakdown within the coil that you can't see or measure. Carried to extremes the coil quits, over heats
etc then you usually have a code for sure without haveing to play checkers with coils.
The total circuit with the coil secondary in series with the plug center resistance and the variable second phase spark resistance under varying cylinder conditions gets quite involved so much so that the load the coils see is all over the range.
Is it any wonder ignition is so sensitive to faults with the plugs in a deep well yet. Seems the cars don't have as high a failure rate as the trucks due to the engine bays being more closed along with other factors.
Theres a lot more to it yet if one wants to learn.

 

Sorry for the late reply just got in from the road late last night, Yeah I installed the K&N straight from the box and it looked pretty oily, more so than any of the others I've installed, but I figured it was OK. This condition first started on I-10 while climbing a long grade in California in the desert with 100 degree plus temps, maybe the high temp and fast air flow made some of the oil get on the MAF. It started to miss and buck, lost power, got a check engine light and I pulled over. After a minute or so I fired it up and it ran but continued to miss at high speed, 75+, and under load pulling a grade. By the time I got home to AZ and got it to the shop the code had been cleared and they couldn't find anything. This was B4 the Volant CAI and exhaust and the Edge programer. I then went on a rescue mission to get my step son's blazer in Tahoe and while pulling it on a trailer the truck missed and bucked on every grade, it was barely 32 degrees out at this time. I took it back to said shop and they diagnosed a bad #5 injector, that was sticking open, fouling the plug. It did not feel like one fouled plug to me but after 4 days I wanted my truck back. I travel all over the Tucson valley and had had 0 problems. I have since installed the Volant stuff and the programmer and had it programed in all settings with no problem, except my right foot is a little heavy :-) Then this trip to Cal and it starts doing it again, anyway here is where the story gets even more strange...I finally got so pissed I had my wife drive when we were leaving the L.A. area last night...The truck never acted up at all and she was driving no different than I do. I am flabergasted, stumped, mad and just plain confused. So now what? I am going to clean the MAF sensor and see what happens. The K&N was the only change I had made when the truck 1st acted up so that's where I'll start. Any ideas appreciated and I'll keep ya'll informed of my luck. Happy New Year to all.

 

Bluegrass - I played checkers last spring which turned in to a big headache . I never did pinpoint the root cause besides washing the motor and I really pored the water to it - no battery was present so I thought I was safe. I intended cleaning every wire and blowing out every connector anyway, and I did. I think it was two days after washing and cleaning that I finally re-installed the battery. I had a misfire at idle, along with multiple misfire codes as well. I also received misfire under 1000 rpm's codes. Checkers (swapping cylinders) - Primary, Secondary and the old fashion ground it to the block tests where done. The coils always passed those tests.

Off course I realize now they were failing under certain loads. At that time those coils (still stockers)had 170,000 miles on them and I believe that somehow I shorted them all out. Each one had its own failing point under different loads. I ended up replacing all coils, plugs and even installed new type 3 injectors all in one shot. After that, The 5.4L had new life , and I still can't recall the truck ever running that strong.

Well I just got back from Auto Zone. It's #8 this time , I think I know what happened . My fuel rail supply line spring clamp connector came apart about two months ago . The spring rusted inside of the connector and broke (a good portion had disintegrated) . When it came off I was doing about 60 mph, most of the fuel being pumped was going over the top of the transmission. I pulled over and the truck was still idling , must have been feeding off fuel left in the injectors and rail because it was completely severed continuing to pump fuel. I shut it down ASAP.

Coil #8 had a fuel bath .

I'm thinking without the dielectric grease that was present at that particular time , It may have ignited that fuel and the truck and possibly me might have been history.

So then what gap are you starting with on new . I'm betting your going with .052 or 3 your explanation. The low side of gap parameters.

 

I gotta get going - just wanted to say - This one went out kind of like that , It ran good, then bad, then good again and finally it stayed bad lol - freakin thing !!, But , yeah , they go out in different ways.

 

I pulled the MAF and could not see anything, but could feel an oily residue on the little housing, so I'm off to find CRC MAF cleaner. P. S. My truck only has 32K on it and this started at about 25K!