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Beast
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Hi Ive had my 2003 dakota 4.7l quad cab 4x4 since 2009. I bought it with 107k on it. It has 184xxx on it now. Today I went on a short trip and it was running fine. When I started it after that the idle was very low and the truck was shaking. It hesitates when giving it gas but once it gets up in the rpm and moving it seems to be fine maybe a small loss in power.

It stalled a couple times, and took a bit to start a couple times. Braking feels normal until im coming to a complete stop it feels like trying to brake with the truck off. I went to Orileys and read the codes. It had 7 codes
P0300 x2
P0121
P0442 x2
P0456 x2

The evap codes have been on since I bought the truck, had it repaired once and the codes came back. I just clear them to pass smog. I have never changed the spark plugs in the time Ive had it, and not sure if they've ever been changed. I just did and oil change and cleaned the air filter on monday.

Im curious is it possible its as simple as a spark plug change to correct? Thats something I can do myself and would rather not take to a mechanic for that. Or what other issues could be causing it. Also is it safe to drive or am I going to damage something else driving it.

Here is a video of the sound. Sorry about the quality.

 

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Im curious is it possible its as simple as a spark plug change to correct? Thats something I can do myself and would rather not take to a mechanic for that. Or what other issues could be causing it.
Oh, it definitely could be something as simple as a bad plug (or bad plug wire).
184k is quite a few miles; do you know when the last set of plugs or plug wires was put in?
ON EDIT: sorry, I just reread & got the part about the unknown life on the plugs. Yeah, that would definitely be a good starting point for you, & it probably wouldn't hurt to do the plug wires as well.
The 4.7 is coil over plug, & I was reading on a GM forum (on coil over plug) about disconnecting and then reconnecting each connector one at a time & if you DCed one & it made no difference or very little difference in your idle, then you had found the bad cylinder.

If you did find a bad cylinder and you wanted to take that further, you could pull that coil & swap it with one on a good cylinder & see if the problem followed the coil (meaning a bad coil) or stayed at the cylinder.

The P0121 is the throttle position sensor. The TPS is fairly accessible & easy to change & shouldn't cost a lot. I've never had one go bad, but I did research the symptoms before & that is not exactly what it sounds like you've got going on, but you might do a google on that & see what you think.
 

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. . . oh, and as far as being safe to drive, I suppose that with a misfire going on, you are dumping a certain amount of unburned fuel into your cat which could ultimately lead to that part failing.
 

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Beast
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Discussion Starter · #5 ·
Oh, it definitely could be something as simple as a bad plug (or bad plug wire).
184k is quite a few miles; do you know when the last set of plugs or plug wires was put in?
ON EDIT: sorry, I just reread & got the part about the unknown life on the plugs. Yeah, that would definitely be a good starting point for you, & it probably wouldn't hurt to do the plug wires as well.
The 4.7 is coil over plug, & I was reading on a GM forum (on coil over plug) about disconnecting and then reconnecting each connector one at a time & if you DCed one & it made no difference or very little difference in your idle, then you had found the bad cylinder.

If you did find a bad cylinder and you wanted to take that further, you could pull that coil & swap it with one on a good cylinder & see if the problem followed the coil (meaning a bad coil) or stayed at the cylinder.

The P0121 is the throttle position sensor. The TPS is fairly accessible & easy to change & shouldn't cost a lot. I've never had one go bad, but I did research the symptoms before & that is not exactly what it sounds like you've got going on, but you might do a google on that & see what you think.
I have only replaced plugs and wires on older cars. Ive looked at how to change the plugs on this truck but dont see traditional plug wires. Just the connectors that plug to the coils. Which wires are you referring to?
 

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My fault; I ASSumed that the 4.7 coil over plug setup was like the coil over plug set up on my GMC. CoilS mounted to bracket on the valve covers and a plug wire from each coil to each plug.

Apparently the 4.7 has the each coil mounted directly on top of each plug. The coils look like this

and instead of a plug wire there is this between the coil & the plug


and note that there is an electrical connector going to each coil.
 

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So if you got the pickup at 107K and you've never changed plugs and it's at 184k, sounds like a good chance those may be original plugs, making the plugs a real good place to start.

With known good plugs in it, if that doesn't cure the misfire, then it looks like you could isolate the misfiring cylinder by disconnecting the connector at each coil and seeing if that affects the idle. If it doesn't on a particular cylinder, and at this point you have known good plugs, I would think that this would point to that coil on that cylinder as the problem.

I am just looking at poor quality black & white pictures in the 4.7 section of my Haynes; is getting at the coils & plugs on that motor a little bit of a bitch?
 

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. . . and, after changing plugs, if you did find a cylinder which you DCed a coil & it didn't affect the idle, instead of just throwing a new coil at it, that would be the point at which you would swap the suspect coil with one on a good cylinder to see if the problem followed the coil or stayed at the cylinder.

But I think that there is a real good chance that changing the plugs will cure the misfire.
 

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I agree with the others, start with replacing those old plugs first. The coil on plugs are relatively easy to remove. sometime hard to disconnect the electrical plug then one nut that holds it down. You will need to remove the air intake and loosen the heater pipes clips to get to a couple of them too. Also check for old broken ends of vacuum lines to the TB. Also check the Idle Air Control valve on the TB as well. That may need to be replaced. The evap hoses can also get brittle and crack causing a vacuum leak and would also cause the evap codes.

I have a 2002 Quad with the 4.7L
 

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I think that you have dropped a valve seat. With the mileage I would be willing to place a bet on it. Common problem with the 4.7 dodge, Chrysler, Jeep Engine’s. You know have a boat anchor. Good luck!
 
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