08 4.6 misses under slight (OD) load. no codes.

Well, as the title says.... I've got a skipping 4.6. I bought my 08 about 3 mos ago with 63k. Primary use is towing so it doesn't get used a lot. On my first trip i had a P0307. Seemed to resolve itself. Today at 65k, it sputtered and missed a lot (hotter weather). I can duplicate it. On the highway on-ramp, get up to to about 40 mph, lay back on the pedal so it shifts into 4th or OD (I can't really tell). As it approaches 45 mph or so, with slight pedal, it starts to miss, and skip. If I step on the pedal "noticeably" or floor it, it smooths out fine. No power loss. If I return to just a slight load, it happens again. (TPS?) The problem is, I drive like an old man. I try and conserve fuel, and never give it any more pedal than necessary. This is where the issue happens a lot. I used my Innova 3160 to capture the data 10 frames before and 10 frames during the skips. I just don't know how to interpret it. The dealer gave me SOME info about what THEY did to the car when they took it in in trade. Coils 2&6, and some steering and tire stuff.

Anyone wanna venture a guess on the cause? I wish I knew what to look for with the OBD II. I can get some of the data in graph format, but it's hard to save. I've heard a lot of peoaple on this forum mention about plugs. I do not know the status of them.

I read here that someone paid $70 for 8 plugs. Is that right? Are they special plugs? Seems kind of high. Also, someone mentioned a spark plug "Extractor". Does a normal spark plug socket no longer work?

Any thoughts, suggestions or comments much appreciated.

Thanks.

P.../NH

its another coil that went bad.

i have the same thing right now 5 out of 8 are replaced under warranty. waiting for others to fail.

I just got up and took it for a ride. only 70 degrees out (was 85 yesterday). Brought it on the same ride that I was able to duplicate it yesterday. No dice. Won't skip.

How do I know which coil went bad this time? Should I "guess" that it is number 7 from the previous P0307 on Memorial day? Again, I have n codes set this time.

Doesn't seem to make sense to replace all remaining 6 at once,

Is there a way to test these?

One more thing I want to throw out. Both times it started to skip was just after refueling. Yesterday I put about 7 gallons in with the car still running (not sure if this has any affect on it or not). I wouldn't think so.


I really have to develop a way to duplicate it. If I can do that, I have a local mechanic that can put a scope on it and go for a ride with me... As long as I can duplicate it. Hopefully that will give me more data.

Thoughts?

Tnx

P.../NH

#7 and 8 spark plug wells fill with water, check for water first.

I've seen a few mentions of "water in the 7 & 8 wells". Most reference the 4.6 L on the F150. Is it the same on the Explorer? How does it get in there? Poor drainage? I don't think I've ever driven this vehicle in the rain. Does it just drain weird while parked.

If it is water, is there anything I can do to prevent it?

If it is water what's the best way to deal with it? compressed air?

Thanks.

P.../NH

My experience

2006 4.6L V-8
Same symptoms; no codes
Had it checked out, nothing found. They added dielectric grease to the rubber boots on the "coil over plugs"; problem went away.
Good luck

I have 2006 EB V8 with 117K miles, all coils original. At 99K miles developed a miss, had to drive on D to keep the rpm high so it was not bucking. Number 8 sparkplug was dead, seized in the head, replaced all the plugs, no more problem. With 2008 you may not have an issue with the plugs removal, but check the build date on the cam cover. Sparkplugs are 12-20 bucks a piece.

Update:

Well I finally had some time to take some action. The skip is getting harder and harder to reproduce. I took the car to a shop that a friend of mine owns. He set up a laptop with a genuine "Ford" module on it. He set it up for me to take with me and drive until I got the engine to skip. It displayed a graph of "relative power" of each cylinder. When I finally got it to skip (just once) it called out cylinder 7. Graphically a deep dip in the relative power to cylinder 7. The one I suspected in the first place as this was the code (P0307) I got the very first (and only time) it happend back in May.

Having that data, I wanted to swap coils 6 and 7 to see if the problem stays with the coil or stays with the cylinder. Today I pulled the coils on cylinder 6,7 & 8. Bear in mind cylinders 2 & 6 were replaced 5-10k miles ago before I got the car. 6 and 7 came off pretty easy. 8 required significantly more effort but released undamaged. They all had grease on them. I presume dielectric. 6 had more then 7, and 7 had more than 8. There was no evidence the jumped out at me. Maybe you can find something I didn't see. Here are some pictures I took. 8 had a little dry dirt/sand/crud baked into it bit I was able to scrap some of it loose and blow it out with compressed air.

https://picasaweb.google.com/103956146819641847893/Ford46LSparkPlugWells?authuser=0&authkey=Gv1sRgCLextY3snLfVpAE&feat=directlink

Comments, thoughts, suggestions welcome.

Tnx

No idea where the dirt came from, I had none of it in mine after 99k miles. You are on the right path swapping coils......then swapping sprkplugs.

Update #2.

The issue seems to be able to duplicate itself pretty easily when I DON'T have my friends analyzer running in the vehicle. When we DO connect it, it is very hard to duplicate the issue. (via OBDII). It's just a coincidence. I drove 60 miles yesterday trying to duplicate the issue, and I barely got 3 failures out of it. Ordinarily (when it happens), I can just about duplicate it at will.

As I mentioned before, it does not appear to be temperature, water, or humidity related. Last time I cleaned spark plug wells 6,7 & 8, I also cleaned the boots, and swapped coils #6 and #7 (see previous post).

This time, fully expecting the graph to point to cyl #6 (now suspected coil #7), it called out yet 3 totally different cylinders. 3,4 & 5. You can see a picture of the graph here. (click on the picture, and then use the magnifying glass to zoom.)

https://picasaweb.google.com/103956146819641847893/2008ExplorerPowerBalance?authuser=0&authkey=Gv1sRgCM60wufM8a7wzwE&feat=directlink

Note the 3 very big dips on cyls 3,4 & 5. This after an hour or so of trying to duplicate it.


With what little data I have to go on, where I did NOT see any hits for cyls 6,7 or 8 (the ones I cleaned last week), I am going to conclude that cleaning them had SOME effect on the performance. I think I am going to clean all the wells and boots of the other cyls, and apply some dielectric grease to all of them and see if the issue returns. if so, I'll have to just see what the results are and act accordingly.

Anyone else?

Tnx

P.../NH

Fuel filter, fuel pump, injectors ??? Or ECM acting up and not sending correct sequential signals to injectors ? Just different theories.

That picture link doesn't work but I would just replace the plugs to eliminate them. Without doing that there's no way to rule them out.

Good post - I'm having the same problems with my wife's 2006 EB V8 and about 75,000 miles. It "stumbles" in the 40-60 mph range when applying light throttle - problem is intermittent with no particular pattern.

Local shop found no codes - recommended fuel injector cleaner first time. Seemed to work a little better, but still having problems. Also tried running higher octane fuel, but still occurs. Just had it back for the state inspection and they replaced the fuel filter this time. Problem reoccurred the first time out. Very frustrating!

I guess it's time to check the coils / plugs, although when I've had these fail on my '02 F150 (5.4, 160,000 miles), there's always been a code that identified the cylinder with the problem.

I've already been through all the transmission issues (1-2 shift, shifter not coming out of park, etc.) shortly after buying this as a low mileage used vehicle. After many years of great experiences with multiple Explorers and Rangers, I've pretty much had it with this one. Can't get squat for it as a trade and can't get it running well enough to sell it private party, so I guess I'm stuck with it until I hit the lottery...

Update/reply.
I took bnhsdad's advice and I figured a last ditch effort (before the arduous task of changing/breaking off) spark plugs would be to try cleaning the boots of the coils and adding dielectric grease.

I cleaned them with a rag sprayed with starting fluid, and bought a tube of Permatex Tune-Up /Dielectric grease.

I have driven the car for about 100 miles or so since and have had no skipping or misses. I realize this is not much of a "litmus test" but in about two weeks I will be pulling my 6000 LB trailer for about 200 miles. I would think this should show SOMETHING...

P.../NH

steve6534 said:

That picture link doesn't work but I would just replace the plugs to eliminate them. Without doing that there's no way to rule them out.

Click to expand...

Hi Steve, Sorry about the link. I just fixed it in the previous post. Here it is.

https://picasaweb.google.com/103956146819641847893/2008ExplorerPowerBalance?authuser=0&authkey=Gv1sRgCM60wufM8a7wzwE&feat=directlink

P.../NH

I had P0302 a couple of weeks ago. With my Scangage2, I was able to get the code after my wife got the engine light.

But after I swapped coils and cleared the codes, I noticed that I soon got some "Pending Codes" (same P0302). I learned from my scangage manual that some vehicles start holding these codes when they start seeing a problem, but not to the degree required to actually throw the check engine light on. You have to dig deeper to get these "Pending Codes". Sure enough, after some more driving, the light came on with the full code. So see if your scanner has this capability, because I know the Explorer/Mounty with throw pending codes.

For my issue, swapping the coils did not move the code to another cylinder. I swapped 2 spark plugs (carefully, by the TSB procedure), and the code moved. I found enough build up of carbon or something between the electrodes, that I think it was starting to short. 1 new plug and all is well. The previous owner had just changed plugs 20,000 miles ago (which I confirmed by the "Champion" label on the pulled plugs), so I'm not ready to change them all again (at $20 per plug) unless I get the problem on another cylinder.

Another update.

I took each coil out 1 by 1 and blew/vacuumed out the spark plug wells, cleaned each of the boots thououghly with a shop rag and some starting fluid, and put dielectric grease on each boot. I have drive about 400 miles so far (250 of that with a 6100 lb trailer) and no skipping at all. Some of it it wet weather too. Fingers crossed...

-P

If you get it skipping again, look for a "Pending Code". Once you have a code identifying a specific cylinder, you can swap that coil with another to see if the coil is the problem. If not, try swapping 2 injectors. If that's not it, then try swapping 2 plugs. If that's not it, it's in the wiring.

Subscribing.

My wife's 07 Mountaineer (63k mikes) just started this about 2 weeks ago. No codes, just a low rpm/high load miss.

Holy old thread! Did not notice this was from last Sept.

Big et al,

I suppose I should have updated this sooner. I have driven 1500 miles or so since I cleaned and lubed the coils and boots. No skipping. It appears that my issue has been resolved.