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OK guys have a question, but first here's a little background

2002 dodge ram 5.9

Replaced spark plugs,wires,cap,rotor about 4 months ago, haven't had a problem since this week.

Check engine light comes on at start up, codes P0300,0302,0307. Engine isn't running that bad, but you can feel a little miss. Hooked up the scanner, and watching the misfire counters it is mainly on 2 and 7 (counts go above 50). other cylinders have lower counts of around 2-3.

Pulled plugs, they all look fine. Did a compression test, all are around the 155-160 mark. Pulled cap, didn't see any carbon tracking or anything weird.

I'm stumped as to what the problem could be. The only real correlation I can see between 2 and 7 is in the firing order, as they are right next to each other on the cap. You don't suppose the cap is bad? possibly the ignition pickup?

If you need more information just lmk, hoping some good ideas pop up
 

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Hmmm, that's a tough one. I would start by checking the simple and cheap stuff first. I would check to make sure the cap is not damaged. You could swap the plugs from another cylinder into cylinder 2 to rule out the spark plug.

My initial guess is the crank position sensor, but only after you check the other small items.

Keep us updated on your findings.

Good Luck!
Mike
 

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Any luck?? I agree with it possibly bieng the crank sensor.
 

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Hi guys new to this forum, I too have the same issue as catfishjoe, I took mine to autozone and the reading said misfire misfire misfire misfire etc... The employee suggested a new cap, rotor and plugs (which I did not buy yet) but im wondering about the crank sensor now- The code scanners do not indicate a bad sensor or can they be bad but "read" good?
 

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Artycat thats a good question.. So good infact im not able to answer that at this time. But im confident someone more knowledgable than me will be able to.
 

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I did some research (although I still didnt have luck finding a testing procedure) and from what I have found, the #1 reason for crank sensor issues is in the sensor wiring harness whether its corrosion or chafing.
As far as a fault code for the crank sensors, my manual says the ODB-II reads-
P03165- No crank sensor learned
P0320- No crank reference signal from CKP sensor at PCM
P0335- Crankshaft Position sensor circuit lost
P0336- Crankshaft Position sensor signal
P0337- Crankshaft Position sensor circuit- voltage too low
P0338- Crankshaft Position sensor circuit- voltage too high
P0339- Crankshaft Position sensor intermittent
P0219- Crankshaft Position sensor over speed signal
P0300- Multiple cylinder misfire

So I think I might go and get my own code reader (new toy!) today to give me a better idea as to what type of misfire I have. Honestly I didnt know I had a misfire issue because the truck runs fine, my engine light came on last week so I had it checked yesterday and here we are!
 

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Hopefully this will shine some more light. My 5.2 threw me P0308, missfire cylinder 8. Clearly mentioned already there are simple explinations such as plugs or wires. Here's some other causes

Faulty coil(pack)
Faulty oxygen sensor
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter
Poor compression
Defective computer (hopefully not)
Running it out fuel

Mines due for plugs and wire anyways and I'm gunna assume that's my problem. You could always plug in a scanner and reset it and see if it comes back haha. Kidding.
 

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Hopefully this will shine some more light. My 5.2 threw me P0308, missfire cylinder 8. Clearly mentioned already there are simple explinations such as plugs or wires. Here's some other causes

Faulty coil(pack)
Faulty oxygen sensor
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter
Poor compression
Defective computer (hopefully not)
Running it out fuel

Mines due for plugs and wire anyways and I'm gunna assume that's my problem. You could always plug in a scanner and reset it and see if it comes back haha. Kidding.
Good thread here guys, I'm having a problem with my 5.9 which is similar to what you all are talking about. My OBD II indicated one of my o2 sensors is faulty when the check engine light came on. What if I have a faulty catalytic converter? Will my scanner pick up that problem? The cat is going on 11 years old now.
 

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Good thread here guys, I'm having a problem with my 5.9 which is similar to what you all are talking about. My OBD II indicated one of my o2 sensors is faulty when the check engine light came on. What if I have a faulty catalytic converter? Will my scanner pick up that problem? The cat is going on 11 years old now.
My experience with a cat going out....it starts to rattle, then one day.....poof..if a piece breaks off and plugs the outlet.....engine dies and stranded on the side of the road. If it's 11 years old, for cheap insurance I'd recommend replacing it with a nice high flow unit. I've been running my magnaflow one for a few years and I love it. You don't need to buy one specific for your truck either....that's all BS and another way to take your hard earned $$$. Just buy one that is the same size as your exhaust pipe. I'd recommend a simple universal 3 inch or so......that's exactly what I've had for many years now with zero issues.

To answer your original question...if you have a code for an 02 sensor.....I'd replace it.

Forgot to mention: The above is on my Dakota with a 5.9...not my Ram
 

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I've had the same misfire issues on my truck lately with rough idle at start up. I just did a tune up and it helped a little but still has a rough idle after the truck has been sitting for a whil, so me and a mechanic friend have about determined its the injectors in my case, dont know if this is the same problem earlier mentioned or not but just thought I'd give my input haha. ill prob be changing injectors out soon so hopefully this will solve my problem!!
 

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Any luck?? I agree with it possibly bieng the crank sensor.
+3 on that.. I have a missfire issue im trying to track down too...I have the new crank sensor already but havent gotten the old one pulled out (bolts are out though) they are tough to get to but not as bad with a body lift....I've replaced injectors and tuneup parts as well as leakdown and compression test myself...

If its not the sensor I fear a collapsed lifter or worn cam lobe... I just pulled a cracked header on the side effected by the misfire and am replacing them with ebay stainless ones (which are identical in design ironically superior welds than my old pacesetters but that for another thread) On the old header you can see the exhaust holes are all black but cylinder#1 (the one giving me misfire code p301 under load) which is light brown so its lean somehow even which new injectors...valve issue not opening enough? Being that it all started after the tranny was rebuilt I'm hoping the crank sensor just got damaged when they removed or installed the transmission since its right there..
 
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