Engine missing when raining? Plugs? Bad gas?

[billb1981]

Figured you all might know the answer to this one....

I have a 2002 explorer, 135k on it. Got a tranmission replaced a few months ago.

Noticed that it will sometimes "miss" when I'm hitting the gas around 55, on acceleration. The problem has happened a couple times in the last week, but only when it's raining or wet. Could this be a plug or perhaps something as simple as bad gas?

I haven't changed the plugs/wires, and don't know if the previous owner did it, but I'm wondering if it's safe to drive a couple hundred miles on a trip this week. I'm assuming it might be something like a bad plug? Or would that be more constant?

I'm thinking about adding some heet and or octane booster in hopes it's something simple like bad gas or condensation in the gas tank?

 

[Cpl. Opey]

First thing is to change the plugs and wires. Added moisture in the air could be causing a plug that's on it's way out to miss more often. Next thing I would do is change the fuel filter and air filter.

 

[Carguy3J]

Is the check engine light on? Have you put a code reader or scanner on it, to see where/ which cylinder the misfire is occuring? This would be very helpful in diagnosing it.

It's hard to say if it's "safe" to drive it on a long trip. A little rough running or a slight, ocassional "hiccup", yeah that's probably ok. A definite and frequent misfire, no, you could possibely do serious engine damage, along with the possiblity of damage to the transmission, as well as the catalytic converter. Not to mention that your fuel economy will suffer.

If it definitely only happens when it is "wet", then I would lean towards, or at least start with plugs and wires, and go from there. Without knowing when they were last done, you should be doing the plugs/wires anyway, as preventative maintenance. Whatever you do, DON'T use Bosch plugs. Explorers don't "like" them for some reason. Stick to Motorcraft or Autolite plugs. Also be sure to get a good quality set of wires. The cheap ones can actually cause misfire/crossfiring, due to poor electrical insulation. I've watched brand wires arc on manifolds and metal brackets. It looks really cool at night, but it won't help your car/truck run right.

You may also want to consider/investigate the coil pack, if the plugs/wires don't help.

 

[billb1981]

Thanks guys, yes, only an occasional misfire, hasn't done it in a few days. I have a new code reader, will it read anything if the check engine light isn't on? (It's not on now)

Also....here's one for you. Pretty sure I'd change plugs myself.....but I called my local dealer, they said something about there not being wires, but coil on plugs per cylinder. $350 to change the plugs, and $100 per coil pack (per cylinder IF it needs it)

 

[Carguy3J]

Thanks guys, yes, only an occasional misfire, hasn't done it in a few days. I have a new code reader, will it read anything if the check engine light isn't on? (It's not on now)

It may. If the light was on previously, and you didn't reset/erase the codes by disconnecting the battery or something, then it will read the stored code.

What cheapy code reader can not do is provide live sensor data. Many times, sensor and components can be "bad", or reporting erroneous data, but not have failed in way that triggers a code. For example, if the ecm expects to see a temp range from the coolant sensor of somewhere between 32deg and 230deg, as long as the sensor is reporting a value within this range, no code is set, as the computer doesn't see a failure. However, the sensor could be "drifting" and reporting wrong information. It may tell the ecm that the coolant is 190deg, when it's really only at 110deg. In this case you may very well experience driveability issues, but have no code pointing to a coolant sensor. Instead, you may eventually get a code for an o2 sensor, showing a "too lean" condition over a period of time, even though the O2 sensor has nothing to do with the problem. (NOTE: this is just an example fo the limitations of a code reader. It's just a tool, not a magic wand. I'm not implying that your problem is related to the coolant sensor or anything else)

As I said, just do the plugs anyway, and go from there. When you pull your plugs, you may very well see exactly what the problem is.

 

[whiteboy91ranger]

does your truck have a distributor moisture in the dis can misfire

 

[whiteboy91ranger]

opps nevermind coil packs still your getting moisture somewhere and definately not a fuel problem check electrical connections near coil packs

 

[DLinkOZ]

If you have the V8, then it's a CoP setup. The V6 is a more traditional coil/plugs/cables setup. And you can pick up MSD coils for $46 each at summit, if you need them. Or an 8-pack of Accels for $200. Just making the point that they're not too expensive. Heck, even the Motorcrafts at summit are only 60 bucks each.