I love my truck, but I am having issues that I can not figure out. I have a 2002 4.7 Dakota. Here is the story.

Here is the deal. I will give you a time frame to work with. About a year ago I gave the truck a generic tune up and put Platnum plugs in it. Up to that point never had an issue. 6 months after the tune up, it started taking awhile to start when it was cold. I did not notice a miss and had no codes. A month later I get code-P0300 (random missfire). Figured it was just bad gas or something. Next month I get P0300 then P0303,P0305,P0307. (miss fire on 3,5,7). I tested every sensor I could find, all seemed to pass. Tried, dry gas and reset codes. Codes came back in the day. Checked coils- all good. Fast forward, from then till now- Injectors cleaned, coils replaced, Crankshaft PS replaced, vacume tested, fuel pressure checked. Nothing!!!! Talked to dealer when I took it for recall last week. He said it was the plugs causeing different resistants so it was tripping codes. He said go to cheap plugs and it will be fixed. Replaced plugs with champion cheap ones. All codes cleared. At about 70 miles I got the codes- 300, 303, 305, 307. Rechecked all sensors. TPS is on the dot closed but at wide open is low .5V. The truck is idling rough, and you can see the truck shaking (just a little). Unplug coil to 1 and nothing changes, same with cyl 3. All others cause it to run worse. I swapped coils around and nothing changed in the way it runs. I am lost, it idles rough, engine light is on, takes for ever to start when cold, you can smell gas when it does start cold, and new plug in cyl 3 has a lite brown glaze on them ( does not wipe off but comes off with sandpaper.) Reset codes again- now getting P303 and P307. HELP PLEASE!!!!! I am at a loss!!!!

 

try different plug brands. we on the forum generally prefer NGK V-power or the autolites 3923 is it? i dont remember the part # off hand but the autolites are one heat range colder.

 

champion plugs are what comes stock, they should be fine. are you gapping them properly?

 

It sounds like you might have some sort of valve issue, much like the 3.7 engines can develop. Thats the only "mysterious" misfire issue I have run across at the dealership. But if swapping injectors, ignition coils, and replacing the plugs didn't change the cylinder misfires, I'd put my money on it being in the heads.

 

after reading this again, i agree with 00dak/rt, i originally thought that when you replaced the platinum plugs with champion plugs it cleared up for about 70 miles, but then started misfiring again. But if it never did clear up the idle the problem could be in the heads or at least one since its only misfiring on one bank. the strange thing is that you can unplug some of the coils and nothing changes, which leads me to believe that it isnt firing anyway, but if you're putting coils that you know are good on cylinders that werent firing before and they still werent firing it must be some other problem than the coils. I would look into seeing if you can eliminate the cam sensor as the problem first. If it were the valves that would explain why you smell gas and idles rough.

 

i forgot about the cylinder head issues, oops.

 

could be a crank sensor issue... I had a bad one when I got my 5.9. Would idle, but misfire on every second cyl. Came up fine on the DRB too, so I replaced it and vroom the engine ran like a champ.

Just a thought. Do a cyl compression test. If nothing comes up do the crank sensor.

 

Crank shaft sensor replaced- a friend was over and we tested the camshaft sensor and it seemed to pass the test he had.

Yes- when I replaced the plugs it took about 70 miles for the codes to come back. Sunday we are doing compression checks on it.

Would it not be odd to have a head problem in 3 cylinders on the same side at the same time? What would be the issue?-- gasket, valves, ????

Thinking about just taking it to Dodge. Just afraid of the cost of them touching it.

 

well, i think since the 3 cylinders that are misfiring on one side does indicate it's a problem with that head. I never thought though, since the 4.7 uses 2 cams, you could possibly have a problem with the cam on that side, but you could have bent a few valves and thats what's causing the problems.
One thing you could do is take it to a dealer, and just pay them the cost of them just to find out the problem. if its something expensive for them to repair because of labor or parts, you could just take it home, find some cheaper parts and have maybe a mechanic friend help you fix the problem yourselves. Ive done that before simply because i didnt have the time to sit there and troubleshoot before.

 

yeah thats agood idea... good luck with getting it solved...