Engine skipping at low RPM under load.

[mlowry]

Hello, I have a 2000 Explorer xlt 4x4 v6 OHV. I took about a hundred mile drive today in sunny weather with no problems. However when I went out later it was raining. It started and ran fine until I started pulling a hill in OD. then the engine started to skip. when I first got it it had been sitting for awhile in the rain and ran very poorly until it warmed up, after that it was fine until it started raining again. I just replaced the plugs, wires, oil, coolant, and air filter. I was told it needed a coil pack when I bought it, does this seem right? It seemed to run fine until it started raining. thanks for any help.

 

[swetrid]

What plug wires did you use? Most aftermarket plug wires are junk, also double check the routing for #4 and 5 as they are close to egr and could be touching and melting wires.

 

[mlowry]

I believe they where autolight plug wires, I tried to be very careful and keep them away from the egr but I'll check and make sure. Also, engine ran rough before I swapped them, then it ran great until it started raining. Thanks for the input. I'm new here and don't know much about explorers.

 

[mlowry]

Update: went out this morning in the pouring rain, checked the spark plug wires they where nowhere near the egr, made sure they where all properly seated. also checked for vacuum leaks. It started fine and ran great at low rpm even under load, but now it seems to be hesitating between 3000-5000 rpm. Could this be a bad coil? Dirty injector? Also, when I changed plugs I went to NGK V-Power plugs, it had Bosch platinum in it before, could this be giving me issues? thanks.

 

[ERUSH97XLT]

Hello,

Sounds like ignition to me, either a misfire or timing.

These ignition systems are extremely sensitive to aftermarket parts: avoid Bosch like the plague. I'm not sure what electrode material NGK uses for their plugs, but I suggest reverting to Autolite or Motorcraft double platinum spark plugs. OEM specs require two different platinum plugs for both cylinder banks. One type has platinum on the center electrode tip, and the other type has platinum on the side electrode tip. Installing double platinum plugs eliminates the "which side gets what" confusion.

You may also be arcing from a small spark plug wire insulation break when the engine bay gets wet from rain. I suggest waiting until dark, running the engine, and spraying a fine water mist around the spark plug wires. Any arcing will be visible.

If it's timing, the only way to know would be to have your vehicle scanned while the engine is under the conditions you describe. The engine's timing must then be compared to specifications under a similar load. There are many sensors which affect ignition timing, so it will be difficult to suggest a particular sensor is at fault without a thorough scan.

A weak coil could cause a weak spark, especially under load. Do you have access to an Ohmmeter? You need to measure the resistances within the coil to see if it's within specifications.

Good luck; let us know how it goes,

ERUSH

 

[mlowry]

Update: It's been raining almost all day and I seem to have developed a consistent miss and it shakes pretty bad around 1700 rpm but seems to smooth out after that but still hesitates at higher rpm. I checked for any jumping spark in the dark and couldn't find anything, even while spraying mist around the coil and wires. I have an ohmmeter but what should I be measuring between? Also wondering if the spark plugs could have anything to do with it since they're not double platinum?

Thanks.

 

[ERUSH97XLT]

Thanks for the update. Please see the link below for measuring the resistance of your coil. Not the image on the bottom of the thread.

http://www.explorerforum.com/forums/showthread.php?t=236721

How long ago did you install you NGKs? If they're not double platinum or iridium, I suspect your gap may be too large for proper arcing due to ignition wear. The ford electronic distributorless ignition system (EDIS) puts out a surprisingly strong spark and will eat poor quality spark plugs quickly (especially Bosch).

EDIT: The moisture concern is another clue. It has to be electrical... my Mercedes ignition acts up when it rains, too. So, I stopped driving it in the rain probably a good plan anyway for her.

 

[mlowry]

Thanks for the link, I just went out and checked resistance and am getting anywhere from 13.4 k.ohm. to 13.9 k.ohm.

I replaced the plugs two days ago, They are not double platinum. so looks like I'm in for more new plugs and a coil

It's supposed to be hot and sunny tomorrow so I'll see if it clears up then. I'll keep you posted.

Thanks.

 

[ERUSH97XLT]

Hold on: That seems like a slightly high secondary resistance, but what is your primary resistance? Should be about less than 1.0 Ohm. I would also search around for Ford's coil specs. I cant' seem to find them in my service manuals, and I've seen conflicting resistance values among aftermarket manufacturers. The link previously provided specified an aftermarket coil, I think.

If you're going to get a new coil, I suggest genuine Motorcraft. It may be more expensive than your big-box retailer aftermarket brand, but you'll have some piece of mind knowing you have the correct coil with the correct electrical specifications. Plus, I've found aftermarket electronics fail prematurely, unlike the Motorcraft products. Again, just a suggestion. These ignition systems can be finicky without quality parts.

Hope this goes well, and best of luck to you,

ERUSH

 

[pitbulldell]

I have found that if i put any other plug besides Autolites in my 95 ex it will skip and or have poor gas milage, also before i would spend the full price for a brand new coil i would try one from a local salvage yard. i picked one up for ten bucks last time i was chasing a misfire problem.

 

[ERUSH97XLT]

before i would spend the full price for a brand new coil i would try one from a local salvage yard.

I would suggest this route, but be sure to test that coil's resistances before installing. If your performance improves or is cured, I would then invest in a new Motorcraft coil. If performance doesn't improve, you didn't waste money on a new coil.

Just my $0.02

 

[mlowry]

Well I went out this morning and bought some autolite double platinum plugs, put them in and wala! problem solved! I have full power again and no miss firing or skipping. So unless this is moister related I think I'm good for now. Thanks for all the help everyone! I'll keep you posted as to how it does in the rain.

Thanks.

 

[ERUSH97XLT]

Good to hear things are working well. Be sure to reset the PCM by pulling the negative battery cable or the PCM memory fuse so it can adjust to the correct plugs.

Be aware: I've had a similar problem, and new plugs fixed it for a few days, then the problem returned. Turned out to be a defective spark plug; the center electrode ceramic was cracked (probably out of the box). Plug replaced, and haven't had the problem since.

Hope it stays fixed

ERUSH