I have a 2004 Dodge Durango 5.7L ...the check engine light is on reading the code P0308 and P0325. The check engine light does not blink but remains on till the code is erased. The P0308 has been there since I bought the SUV last year, the P0325 showed up after we changed the fuel injectors...So I'll let you know we have changed the fuel injectors, spark plugs, tested the spark plug wires (they are good), tested the coils (they are good), did a compression test (it was good), changed the intake sensor, the knock sensors, and the transmission speed sensors. We also changed the exhaust manifold gaskets and bolts as both side were leaking, there is still bolt that needs to be removed and replaced on the drivers side, I don't know if this would be related or unrelated. I am at my wits end as to where to go from here...The only symptom of the misfire is when the car is idling, it has a slight jerking feeling. Once driving you can no long feel the bumping... There is no loss of power when accelerating. I get about 400 miles per tank...Does anyone have any idea's what else could be causing the #8 misfire and the knock sensor code to be showing up. Thanks

 

The only things that come to mind is have the intake gaskets been changed out and are you running copper OEM spec plugs? These things don't seem to like anything but copper every 30k, and copper conducts the best but wears out the fastest. Mine never had an issue, ever, until after the 60k service when I tried platinum plugs.

An exhaust leak will cause an issue though because it can suck air in and foul up the 02 sensor reading at idle so the PCM compensates the wrong way. You can borrow a reader from the parts store to check your fuel trims at idle and if they're much over 5% it could be a problem. Does disconnecting the battery and resetting the PCM clear things up for at least a few minutes?

 

Thank you for the reply...The spark plugs were changed a few months ago, and I did replace them with platnium plugs, but wouldn't that cause multiple misfires? We haven't replaced the intake gaskets.

When I disconnect the battery and reset the PCM, it usually takes between 50 to 100 miles for the check engine light to come back on and the knock sensor code shows up first.

 

Have you moved the coil from #8 to another cylinder and reset to see if the fault will move with the coil? What does the #8 plug look like compared to another one?

When you disconnect the battery, is the running condition the same as before, jerking and noticeable missing or does it go away and then come back?

On mine the NGK platinum plugs never threw a misfire code....it just shut off a couple of times. Never happened in 60k miles of copper plugs. Mileage also got a little worse which didn't make sense as I did a full 60k service by the book (other than wrong plugs). Still got 12mpg towing 6000 lbs but normal mpg dropped. Check thread 10 here:
http://www.jeepforum.com/forum/f309/.../#post15750211

 

We did switch the coil with another cylinder...the code still came up as P0308.

After I changed the intake sensor (IAT) and the PCM was reset, the bumping or slight jerking feeling was gone, I thought I had finally fixed the problem, but after driving about 100 miles the check engine light comes back on and the bumping came back...and it only bumps when idling, when I'm driving everything is smooth, everything drives great.

I should maybe mention, one time I was driving home from Tucson and it was pouring rain...The windshield cowl on my Durango was not snug to the windshield, and was allowing all the water to run down over the engine...The vehicle shut off (no power steering, no power brakes) while I was traveling at 80 miles per hour...the check engine light was flashing, and the lightning bolt symbol light came on...I managed to pull over turned off the ignition, waited a minute and then restarted the car, the car started the lightning bolt symbol light turned off and the check engine light stopped flashing...I then drove in the slower lane all the way home, but this happened 11 times before I finally made it up my driveway. It has only done this once to me thankfully, and I have replace the cowl... but I don't know if this has ever happened to this vehicle before as I just bought it a year ago with 93,000 miles on it...I have since driven it another 13,000 miles with the misfire code. I don't know if the water issue could have been the cause of any of this.

 

Sounds like it's learning its way back to bad condition after you reset it. I would look at the fuel trims to see if they're getting out of whack due to something. Unfortunately if it's really misfiring that can also cause the fuel trims to adjust. Cylinder 8 is on the passenger side but your missing bolt is on driver side. Hmm. Did you swap injectors on that cylinder too? Swap the wires?

Changing out the plugs to copper might be the cheapest thing to try. Did you also move plugs from cylinder 8 to see? If I ever drop a plug, I just throw it away instead of installing it. They can be fragile.

The intake manifold gaskets are known to be an issue on these as well. If you get a can of starter fluid or brake clean and spray around the intake manifold where it meets the heads and the idle fluctuates you can have a vac leak. This causes issues also.

You've got an aggravating problem on your hands.

 

I had all the injectors replaced, and we did swap the spark plug wires also...still pulled up the misfire #8 code Tomorrow I will do what you suggested with the starter fluid to see if there is any difference, before I change all 16 spark plugs again lol but I think if it was the type of spark plugs, it would affect other cylinders as well, but I don't know you're right I have a very aggravating problem on my hands lol...Thank you for all your suggestions, we're going to be working on it tomorrow, I'll let you know if it gets figured out or not