Running rough after spark plug and wire change.

[portedav]

I've searched the forums and cannot find anything that I am sure applies to my situation.

Today I changed the spark plugs and wires in my 2008 Explorer XLT 4x4. It has 125,000 miles on the original Motorcraft plugs and wires. Other than a slight drop in MPG over the past eight years, I've had no issues, so this was mainly scheduled/preventative maintenance.

The idle was smooth, and during my test drive around the neighborhood, I had no issues. Success?

However, during a 8-9mi drive to the grocery store I had multiple issues with hesitation or stuttering. Usually under acceleration.

Accelerating from a stop I had a slight hesitation or stutter pretty consistently. Under constant speed (est. 40-45mph) I had a smooth ride except twice when the engine speed increased to maintain speed going up hills. One the interstate portion of the drive (approx. 70-75mph) I had a smooth ride only once did I notice a slight stutter.

It almost as if the gas is cutting out. I don't want to diagnose myself, that's why I am here. But, the sensation is not a regular misfire, as if a plug or wire is out, but rather a sudden, very brief loss of power.

I hope this description makes sense. Looking for advice on things I could check. Trying to avoid taking it to the shop for what could be a simple check/fix.

David

 

[BootyDo]

First, welcome to the boards!

As for the issue, there are more experienced folks than myself, but a few suggestions can't hurt

When you installed the new plugs and coils, did you verify the plug gap and make sure the connectors were attached firmly and in the correct order - meaning no crosswires? Also, what engine was this on - the 4.0 or 4.6? And lastly, did you disconnect your battery by chance when doing all this? Might just need an idle relearn.

 

[4D X]

Maybe the computer needs time to adjust for the slight changes from the spark plug change? If so it should get a little better every time you drive it

 

[portedav]

Thanks for the replies and the warm welcome. Nice to find a place dedicated to Explorers!

So, I was REALLY having an issue when I first cranked. Shaking. Popping. Rough idling. I had switched the 4 and 6 wires on the ignition coil. Fixed that and the cranking and idling was MUCH improved.

Also, rechecked each boot. Seem to be seated correctly.

I checked spark plug gap. It was a tight 0.052.

I'm using Bosch Platinum if that matters. I've seen some complaints about Bosch plugs. The wires are Motorcraft.

Potential screw up alert! - I did NOT disconnect the battery. Read later that I should've. Would it make sense to disconnect it now, let the engine computer reset, and then try again tomorrow?

EDIT: It's a 4.0L.

 

[BootyDo]

Good Luck! And if you haven't found FordTechMakuloco on YouTube, a LOT of great information. This is his idle relearn. I do the gator clips as well but I'm sure you can use any wire you have lying around. And if I'm not mistaken, I thought I saw something like disconnecting the battery and turning on something like the headlights, (which probably wouldn't power up), would drain the PCM capacitor too. Main thing is making sure you have enough time for the idle relearn.

Also, I know you didn't mention it before, but if you're at 125,000 miles and doing an idle relearn, might be a good opportunity to clean the MAF & Throttle Body. Maybe 1 hour from disassemble to reassembly for a "fun" Saturday morning project.

 

[Tech By Trade]

Funny, its usually 5 and 6 guys mix up as they are reversed. battery wont make a lick of difference. If its still having issues take a real close look at the wires. My last set (NGK) was replaced 3 times before I got a set that wasn't damaged from factory or missing a wire in the box.

 

[portedav]

Have been searching and reading through some other, older threads today and have a couple of new (maybe rookie) questions:

1) I see a lot about needing to swap out plugs and wires that are DOA? Is it really that common? Is it likely the new set of wires and plugs are bad from the factory?

2) In another thread I saw the hesitation and bumping while accelerating as feeling like a "rumble strip." Today driving to and from work, I realized that's a decent description for what I'm experiencing. So, anyway to tell if it's the torque convertor vs. bad plugs? Wouldn't it be a HUGE coincidence for the TC to go out immediately after a plug and wire change?​

David

EDIT: Formatting.

 

[Flag Gibby]

Have been searching and reading through some other, older threads today and have a couple of new (maybe rookie) questions:

1) I see a lot about needing to swap out plugs and wires that are DOA? Is it really that common? Is it likely the new set of wires and plugs are bad from the factory?

2) In another thread I saw the hesitation and bumping while accelerating as feeling like a "rumble strip." Today driving to and from work, I realized that's a decent description for what I'm experiencing. So, anyway to tell if it's the torque convertor vs. bad plugs? Wouldn't it be a HUGE coincidence for the TC to go out immediately after a plug and wire change?​

David

EDIT: Formatting.

If you are purchasing motorcraft brand plugs or wires, no it is not common, but bosch and champion brand are known for issues straight out of the box. V6 or V8 motor on your vehicle, because those issues have completely different possibilities depending on the engine?

 

[BrianDye]

I cant offer much insight here, as im chasing a rough idle problem that I hoped would be fixed with new plugs, but from being on this forum over the years, take those Bosch plugs out as fast as you can and swap them with the OEM Motorcraft or Autolite plugs. Nobody ever has anything positive to say with Bosch plugs/wires on these forums.

I am running Autolites, and have had no issues. Swapped my OEM plugs around 85k.

 

[fordbluefamily]

I have nothing nice to say about Bosch plugs in a 4.0 other than they run better when I pull them out. There are no improvements to be had in this engine with regards to spark plugs, so I would get some motorcraft double platinum plugs and change them. The waste spark system these use is very hard on plugs as they fire twice as much as they need to. I also have better luck with motorcraft wire sets. A bit pricier but worth it to me.

 

[BootyDo]

When you guys are saying spark plug wires, are you referring to just the coils? I will say I went with Accel coils, (it was actually cheaper for a set of 8), and the improvement was immediate. That said, one of my stock coils went bad so of course it would be immediate. I noticed no difference on the OEM Motorcraft spark plugs, (also around 85k).

 

[fordbluefamily]

Nope. Talking about a 4.0 v6 that still uses a single coil assembly and spark plug wires. The op never told us what he had though, although with either engine I would never use Bosch

 

[swshawaii]

Post #4

EDIT: It's a 4.0L.

 

[portedav]

Post #4Quote:
Originally Posted by portedav View Post

EDIT: It's a 4.0L.

You got it. Thanks for noticing my edit.

Message received loud and clear and for about $18 I'll have the OEM Motorcraft plugs (SP412) delivered tomorrow. I'll get them in right away. Should go quicker this time as I've recently practiced. Will update here once I see how it's running with the OEM replacements.

One question about routing the wires - on the driver's side, it's easy, lace them through two wire looms and onto the plugs they go. The passenger's side is a different story, they go into a "tray" behind the alternator, make a hard right down the side of the manifold and then drop down to the plugs below a mess of air intake, A/C parts, and vacuum hoses. Any suggestions on how to get the new wires into that track? Or is routing them a different way possible?

David

 

[fordbluefamily]

I actually removed the alternator to get them into that tray on my 04. It is fairly quick to do. Just make sure you know which one is which after you get them routed there. Or you could just lay them behind the alt. The PO of my 04 Mounty cut the factory wires and left the chunks in this this thing and just laid the new ones on top....it looked ridiculous

 

[portedav]

...Or you could just lay them behind the alt. The PO of my 04 Mounty cut the factory wires and left the chunks in this this thing and just laid the new ones on top....it looked ridiculous

I considered this, so I'm glad you've confirmed it's a bad idea.

Also, thanks for continuing to follow and comment. This is my first thread here, and really the first time I've attempted my own maintenance, so it's good to feel like there's a place to go for answers and support.

David

 

[BrianDye]

I considered this, so I'm glad you've confirmed it's a bad idea.

Also, thanks for continuing to follow and comment. This is my first thread here, and really the first time I've attempted my own maintenance, so it's good to feel like there's a place to go for answers and support.

David

I've joined the corresponding forums for almost every vehicle I've owned, and this one by far is the most helpful, and active. You can always find answers here and if not, someone is always willing to go the extra mile to help.

Let us know as soon as you swap the plugs, very anxious to see if that fixes your issue!

 

[fordbluefamily]

I considered this, so I'm glad you've confirmed it's a bad idea.

Also, thanks for continuing to follow and comment. This is my first thread here, and really the first time I've attempted my own maintenance, so it's good to feel like there's a place to go for answers and support.

David

I don't know if it's a bad idea really, it just looked bad with the chopped wires hanging out and does increase the chance of a wire being pinched. This forum is a good one and really helped me through the years.

 

[portedav]

I'm back with an update!

Motorcraft SP412 (OEM) plugs delivered on Wednesday. Wasn't able to make the swap until this morning.

In the meantime, I had to drive to work and back Thursday and Friday. By Friday evening the CEL was on... So I was REALLY hoping the plug swap would clear things up.

First thing I noticed was all of the Motorcraft plugs were gapped in spec and consistently from plug to plug. The Bosch plugs I put in last weekend were inconsistent between plugs, and, even though they were supposed to have factory-spec gap, they were all under gapped at about 0.050.

Following advice from this forum, I disconnected the battery before doing anything this time.

For each plug I pulled the boot, cleaned the inside, removed the plug, and cleaned the threads on the block. With the new plugs I was much more careful with the anti-seize this time. I don't think it was an issue, but was extra particular in making sure the the electrodes and ceramic were spotless. The new plugs seemed to go in much easier than the Bosch. Same as last time I used a flat-blade screwdriver to smear a small amount of dielectric grease inside the boot. And, of course, I finished by fitting the boot back onto the new plug.

Knowing which extensions worked best for each plug location, and keeping things organized better made the job go much quicker this time.

So, all six were done, and the battery is reconnected. I turn the ignition. No CEL. Instead its in "limp" mode with the wrench light on and n throttle response. I let it idle for a few, cycle the ignition, and now no lights. Perfect idle. Great throttle response.

I finished up with a drive around the neighborhood, up and down a few hills, and a couple of hard accelerations. Night and day vs. last week with the Bosch plugs. And much smoother acceleration and idle than I've had in probably 30-40k miles!

Thanks everyone for all of your help and advice. Without you guys I probably would've rattled and rolled and backfired my way to the shop assuming I had messed something up.

Hope everyone is having a great weekend!

David

EDIT: Fixed a typo.

 

[BrianDye]

Awesome! Glad the new plugs fixed your issues. It's amazing how bad those Bosch plugs really are!

I was also pretty surprised how easy it was to change the plugs on these trucks. I did it with no special tools, just a couple extensions and the plug socket. Previous vehicles for me have been nightmares trying to change plugs out, including one of my past generation Explorers, one of the plugs was nearly impossible to get to.