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02 3.8 caravan Misfire

16576 Views 18 Replies 10 Participants Last post by  Carbuff2
Hello all! Just wanted to hear some opinions on a problem with my van. Its a 2002 Dodge Grand Caravan ES with the big 3.8 v6. Had the van since new and it only has 59k miles on it, its been great and I love it! :thumb: However its run into some problems recently, I have a scanner and pulled 2 codes
P0135: 02 heater circuit (bank 1, Sensor 1)
The original sensor is on the van right now, would putting a new sensor on solve this problem? Also to note I get pretty low gas mileage and I keep up on maintenance such as air filter, cleaning throttle body, tune up etc..

P0306: Cylinder 6 Misfire detected
The van got new plugs and wires last summer, it is not a horrible misfire like its not bucking all over like a mechanical bull haha but if I put my hand by the tailpipe, the exhaust comes out a little uneven so something is up. I pulled the plug on cyl 6 and it looks to be ok, today I moved the plug from #6 to a different cyl to see if the code pops up again but on a different cyl this time. Any ideas what commonly causes misfires on these engines?

Hopefully I can get this all figured out soon because it has to pass NY state emissions inspection in a month. Safety is all good, I just replaced front brake pads and rotors and the tires have tread on them, oil changed etc I take good care of it! All the best - Anthony
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P0306? Can be several causes: http://www.obd-codes.com/p0306

P0135? Usually the heater coil in the sensor burns out. Can be wiring or the PCM.
I pulled the plug on cyl 6 and it looks to be ok, today I moved the plug from #6 to a different cyl to see if the code pops up again but on a different cyl this time. Any ideas what commonly causes misfires on these engines?
So what does this mean...did the code come back up on a different cylinder, or did it not? If it did, then I would suspect the plug may have a small crack, incorrect gap, etc. If not, maybe the plug wire.

The van got new plugs and wires last summer
So did the problem start with the new plugs and wire?
So what does this mean...did the code come back up on a different cylinder, or did it not? If it did, then I would suspect the plug may have a small crack, incorrect gap, etc. If not, maybe the plug wire.

So did the problem start with the new plugs and wire?
The code hasn't come back yet because I still have to drive the van more lol, but yes gonna keep an eye out to see if its on a different cyl or it stays on #6. The check engine light doesn't flash and it does not come on instantly, usually I have to drive it for a few days to a week for it to come back. And the problem started about 2 months ago so about a year since the new plugs and wires, thanks for responding!
P0306? Can be several causes: http://www.obd-codes.com/p0306

P0135? Usually the heater coil in the sensor burns out. Can be wiring or the PCM.
Thanks for your response! Would a new o2 sensor fix it you think? Also I have bad gas mileage could the 02 be the culprit?
Ok, so today I drove the van a bit and the engine light came on. Scanned it and it was the same 306 code misfire in cyl 6. So the plug wasn't the problem. How would I test a wire or even the coil?


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The O2 sensor has a pre-heater circuit which warms it up, and allows it to fully function quicker. This reduces emissions at start-up.

But, it has nothing to do with your miss.

If your state has emissions testing, you'll certainly need to change it, otherwise, it's up to you.

Can't help with your miss, other than to search all the usual suspects.
Since you have a 2002, you should check the wiring harness for the fuel injectors.
I am surprised nobody has mentioned it yet.

Please see this thread:
Melted injector wiring harness 2003 Town and Country
http://forum.chryslerminivan.net/sh...injector-wiring-harness-2003-Town-and-Country

One other issue as the vans age is the coil pack
Here is one thread on it:
P0302 code, how to test if coil pack is bad?
http://forum.chryslerminivan.net/showthread.php/30794-P0302-code-how-to-test-if-coil-pack-is-bad

Good luck
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Ok everyone, thank you all so much for responding! :) I ordered a coil and 02 sensor and they took forever to get here but today they finally came and I put them in. Gonna drive the van this week and see what happens! Also wanted to ask, could a very old and probably plugged fuel filter contribute to the problem? Mines never been changed :Wow1: I know its annoying to do because its on top of the gas tank ugh. Well thanks again everyone, hope its fixed already!
Since you have a 2002, you should check the wiring harness for the fuel injectors.
I am surprised nobody has mentioned it yet.

Please see this thread:
Melted injector wiring harness 2003 Town and Country
http://forum.chryslerminivan.net/sh...injector-wiring-harness-2003-Town-and-Country

One other issue as the vans age is the coil pack
Here is one thread on it:
P0302 code, how to test if coil pack is bad?
http://forum.chryslerminivan.net/showthread.php/30794-P0302-code-how-to-test-if-coil-pack-is-bad

Good luck
^^^ I like these answers a lot ^^^

If these are not the solution, a step that isn't too difficult would be to switch locations of the fuel injector #6 and another. If the misfire follows the injector, it's probably the injector.

I also suppose the suggested fuel filter is helpful but not likely, IMHO.
it's rarely the coin, but I chased the same problem and the solution was the coil.
Well after about a week of driving, the van finally decided to throw the p0306 code back at me. When accelerating hard I hear a popping sound occasionally and can almost feel it in the gas pedal. However if I put the van in park or neutral and rev the engine high like to 4000 RPMs it sounds fine. Only notice the popping sound when driving and accelerating hard, mostly at the higher end of second gear. Tranny fluid is good and clean so I'm assuming the gear might have nothing to do with it. Also the engine was bucking and such, did a little power braking and discovered that the front center motor mount and the upper driver side tranny mount were on their last legs so I replaced those.
At least the 02 sensor code hasn't come back on and the engine isn't moving around as much thanks to motor mounts.
What I have done so far:
Checked plugs and wires -(new set put on last summer) All seemed fine
Put a new coil pack in - this at least made the popping happen less often but it still happens
Added some lucas fuel treatment to the gas tank with hopes of cleaning up the injectors ( I know this stuff really doesn't do anything but my local store had a very good sale on it so I figured it was worth a shot!)

Well friends where do I go from here? Compression test? I have a tester just it would surprise me if that was the problem on an engine with just under 60,000 miles!But hey you never know.
What are good compression readings for this engine? Other ideas, cleaning any of the sensors like the MAP etc.. Bad catalytic convertor? Thanks all!
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As stated before check your injector wiring harness for the fuel injectors. It could possibly be because of that

Melted injector wiring harness 2003 Town and Country
http://forum.chryslerminivan.net/sho...wn-and-Country
Hey guys I think I may have fixed the problem! I had these weird bosch plugs with 4 grounds over the electrode and my friend told me those plugs are absolute crap, so I threw a set of champion platinums in there and just drove it, no more popping! Ill drive it for a week and keep my eye out for codes! If that was the fix, everyone stay away from those bosch plugs! Thanks all :)
Good move. Wisdom here is ONLY to use the Champion Double Platinum (as fitted OE).

Mine started misfiring at about 60 K miles also, seemed that the gaps were twice as wide as they should have been...

PS: just as a preventative thing, I'd check that wiring harness under the power steering reservoir...
Thank you Carbuff2! Hey we have the same car, same trim and color too! haha :ThumbsUp:
Yeah I generally stick with OE parts however last summer my uncle did the tune up with parts he got. In my chevy impala I have the OE delco plugs and I did a tune up, replaced everything OEM and it runs perfectly! I think the general list is GM- Delco Chrysler- Champion Ford-Motorcraft? Well I learned my lesson lol and yes the wiring harness which I got a nice look at when I changed the coil looked to be in fairly decent shape, not burnt or melted through thankfully! And yes I made sure all my gaps were good before I put them in today!
Hey guys I think I may have fixed the problem! I had these weird bosch plugs with 4 grounds over the electrode and my friend told me those plugs are absolute crap, so I threw a set of champion platinums in there and just drove it, no more popping! Ill drive it for a week and keep my eye out for codes! If that was the fix, everyone stay away from those bosch plugs! Thanks all :)
Yes these vans don't agree with any other brand of spark plugs other than Champion Double Platinum. I think the Bosch brand doesn't agree with these vans at all lol!
yes the wiring harness which I got a nice look at when I changed the coil looked to be in fairly decent shape, not burnt or melted through thankfully!
You DID remove the outer sheath to check the wires inside, I hope. :Wow1: The damage is not readily apparent from the outside. That is why many owners (and pro mechanics) miss suspecting harness damage ass a cause of their maladies.
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