Misfire in Cylinder 3 and rough idle

[StageLeft]

65k miles on a 2004 MPV, original plugs. 18 months and about 15k-20k miles ago I got a code, no symptoms. It was a cylinder 3 misfire. I ignored it and the check-engine light went off and has been gone since. Today I started it up and quickly noticed that the light was on and there was some small hesitation when accelerating with a rough idle and just something off, like that cylinder wasn't working. I got it checked and:

P0108 MAP/BARO circuit high input
300 random/multiple cylinder misfire
303 cylinder 3 misfire

After 5 more restarts of short trips and another 15 miles the light is off. After the first trip the symptoms were gone.

It was pissing down rain yesterday and also very humid today. Is it plausible that some moisture is somewhere in an ignition coil (presuming this vehicle has 6, that is). If a plug was bad, it wouldn't have self-repaired, which is why I wonder if moisture is a problem somewhere...

Thanks!

 

[Vette73]

swap plug and coil with another cyl. If they new Cyl comes up as a miss then replace coil and/or plug. If it still sticks to cyl3 then you have a problem in that cyl.

 

[StageLeft]

Originally posted by: Marlin1975
swap plug and coil with another cyl. If they new Cyl comes up as a miss then replace coil and/or plug. If it still sticks to cyl3 then you have a problem in that cyl.

Good idea--which would be the third cylinder? I cannot remember if this is commonly specified in the manual or not but I know cylinders go back and forth as to which is which

 

[alkemyst]

Originally posted by: Marlin1975
swap plug and coil with another cyl. If they new Cyl comes up as a miss then replace coil and/or plug. If it still sticks to cyl3 then you have a problem in that cyl.

and wire.

I had a Cylinder 3 misfire (coincidental) and my wire spec'd out ok for ohms, but it was still failing.

New wire fixed it.

 

[Zenmervolt]

Plugs and wires (if one has failed, it's best to change them all). If it has a distributor, replace the cap and rotor as well.

ZV

 

[SAWYER]

This was happening on my wife's van and I replaced the plugs and wires with no luck, then I discovered the coil pack was bad.

 

[StageLeft]

Google finds only questions, no answers, for cylinder layout. Would it be, when looking at the engine from the front bumper something like this?

123
456

?

 

[c3p0]

Matt, check here for the information you seek. Your problem is most likely plug wires. I would recommend changing all plug wires and spark plugs. If the problem continues after that then it's probably the coil. But the spark plugs and plug wires are the weakest link. Good luck!!!

c3p0
:beer:

 

[Vette73]

^

His car has no plug wires. It has 6 coils with 1 coil on top of the plug for each Cyl. Thats why in that type of problem I would switch the coil and/or plug from 1 cyl to another and see if ther problem follows the parts or stays with the cyl that has the miss.

Rockauto.com shows the coil at $48 each and the plugs anywhere from $2 to $8 each.

 

[AMCRambler]

He can't swap the coil without knowing which cylinder is number 3 though. Unfortunately I don't know how you can tell either.

On older cars the cylinder firing order was cast into the intake manifold or the engine block. Then what I would do to figure out which cylinder was number 1, I would take the plugs out of the first cylinder on the drivers side and the passenger side, put a long screw driver in one of the plug hole so that it was resting on the top of the piston, put a breaker bar on the crank bolt and crank the flywheel around until the top dead center hash mark on the fly wheel lined up with the mark on the timing cover and then check the screw driver to see see which piston was pushing the screw driver out of the plug hole the farthest. The one sticking up the furthest at top dead center was number one.

With newer cars you can look at the coil pack if it has one and usually molded into the plastic you'll see the cylinder numbers and you just trace the spark plug wire back to the plug and then you know which cylinder is which. Since this car has no coil pack my guess is its got to be labeled on the cylinder head somewhere. Or maybe on the intake manifold where it bolts to the head. But I'm not sure.

 

[Vette73]

^

c3p0 already gave a link above...

http://autorepair.about.com/li..._orders/bl-fo-0371.htm

 

[AMCRambler]

Originally posted by: Marlin1975
^

c3p0 already gave a link above...

http://autorepair.about.com/li..._orders/bl-fo-0371.htm

Ah ha! Nevah mind! Good find C3p0

 

[kalrith]

I had the same problem on my Mazda Tribute and found that I had two bad ignition coils by swapping them with others. If your engine's like mine, you'll have a heck of a time getting to the cylinder three (you have to remove the intake manifold among other things). If you do need to order new parts, look here first. I've ordered from them a couple of times and had a great experience both times. I saved about $40 by ordering my ignition coils through them instead of at AutoZone.

 

[StageLeft]

Thanks for the diagram. I'll switch coil 3 with 2. I had the problem this morning again but now I'm back in business once it runs for a few minutes.

Originally posted by: kalrith
I had the same problem on my Mazda Tribute and found that I had two bad ignition coils by swapping them with others. If your engine's like mine, you'll have a heck of a time getting to the cylinder three (you have to remove the intake manifold among other things). If you do need to order new parts, look here first. I've ordered from them a couple of times and had a great experience both times. I saved about $40 by ordering my ignition coils through them instead of at AutoZone.

Well of course, this had to be the most inaccessible one, didn't it? I've switched out some coils on a maxima before but it wasn't a big job. I'll see how this is. I am getting better at accessing the small spaces at least

I bet it is a coil.

 

[radioouman]

If the coil pack design is anything like my Sebring, the spark plug boot has a big spring running through it as the wire. Corrosion can develop on both ends of the spring. Obviously the end that touches the spark plug is easy to diagnose and to clean. However, the boot pops out of the coil pack, and then it is possible to clean the other end of it. I used a fine file to remove the corrosion. After I did this, the engine ran fine again.