2002 Dodge Dakota Multiple/Random Cylinder Misfire ( 02 Dak

So you are getting a P0300 code? Did you do the tune up yourself? If so are you sure that none of the wires are crossed and all the plugs are gap correctly?

The tune up was done by Midas, I have taken my truck to the dealer ship as well as another local shop. They all tell me the same thing that it runs fine for us. Once I take the truck out of the parking lot it acts up again. I feel like I am getting know where with the shops that is why I am looking into possible sensors now.

Well I think you need to get the vehicle scanned and see what codes are stored. If you have any codes get back with me and let me know what the codes are. The thing is anybody could make a mistake so you could still have a wire crossed or a plug that is not gap correctly. Some plugs get hit during installation and that changes the gap anything could happen. Good Luck.

The codes that I have been getting and that are currently showing are P0300Multiple/Random Cylinder Misfire, and P0302 & P0304 Cylinder 2, 4 misfire. I have also showing P0305 and P0306. The reason I don't think its a crossed wire or a gap issue because the cylinder misfires have been changing cylinders. If it were a gap or wire issue wouldn't it continue to run ruff and not straighten itself out?

Well I think your right if it was a crossed wire are plug you would have this issue constantly.
Have you checked for vacuum leaks. Sometimes a vacuum hose can be unintentionally disconnected causing a lean mixture during warm up.
There are a number of things that could cause the computer to set this code. The tuneup you have just completed can theoretically rule out the secondary part of the ignition system (Wires and plugs.) And the fuel injectors. Did you replace the fuel filter? It still may be on the primary side. The coil packs could be breaking down and or the fuel injectors may be giving you a lean mixture. The other thing I am leaning toward is the cam shaft sensor. If I am not mistaken there were some issues with the Dodge 4.0 L cam sensor hanging and causing this random misfire. It is a little puzzling because of the cold weather issue. When it is cold the engine needs more fuel and the computer is running the engine on preset parameters. This is called the open loop mode because it is not regulating the spark and fuel based on input sensor information (The Closed Loop mode). So it seems like it may be a lean mixture problem since the engine does better after it warms up. That is the only thing that makes sense because a input sensor should be constant as well except for the O2 sensor which should set a code. The electrical problem on the primary side would get worse as the engine heated up. I would have the system scanned again make sure that you are not getting any other codes. If it were due to the other sensors you mentioned in your original post it should have a code stored in the computer. If not I would check fuel psi. And change the fuel filter if that has never been done. Good Luck please let me know what you find

Toolman,

Thank you for your help. I have not had the time to work on my truck but planning on doing that this weekend. I was thinking about the it maybe being the cam sensor. I think the fuel filter is a good idea period, because I haven't changed that since I have got the truck. I have replaced two of the fuel injectors already and that didn't seem to do anything for the problem, which is why I started leaning toward it being a sensor. I will have to look into replacing the cam sensor and the fuel filter this weekend. Now you were talking about because of the cold weather that the computer would run a leaner mixture. Would it still be possible for me to get the back fires while driving with a leaner mixtuer?

Sorry about the mis-understanding. Actually what I meant was a cold engine actually needs more fuel. Therefore the timing needs to be advanced in order to burn the fuel. There are many ways that manufactures have done this over the years the latest being the computer and sensors. One more question Is the check engine light staying on all the time? Please let me know how it goes maybe the fuel filter will clear it up for you? A lean fuel mixture will definitely cause a mis fire.
Don't forget to give me some feed back if you think I am deserving of it.
Good Luck

I went ahead and changed out the cam sensor and now my truck will not start. I went to double check to make sure the wires were set correction on the distributor cap and even moved them around. I don't know if I need to reset something to get it up and running again. The engine turns over but does not even attempt to start now. Is there a fuse for the fuel injection system that I might have blown that is not inside one of the fuse panales that I am not see. Second the fuel filter is a life time and is part of the fuel pump. The only way to replace the filter is by replacing the fuel pump. As for the fuel mixture being richer would explain why I get the backfires when I drive it when its not warmed up.

Sorry to hear that. Well the first thing we need to determine is are you getting a spark. Remove a plug wire from a plug insert a screw driver with a insulated handle which all should have. Hold the screw driver about 1/4 inch away from engine ground while someone turn the engine over. Make sure you have the metal tip of the screwdriver inside the plug wire. If you get a nice blue spark then let me know. It would be the fuel and or the timing. Get back with me when you find out if you are getting a spark. I will try to monitor this a little closer and respond quicker.

I just check to see if there was spark and there was. The spark was not bright blue but an orange color. Where is the next I should check?

There is a valve on the intake it looks like the valve you put air in your tires. Be careful when you do this if the fuel system is working there will be fuel under psi. Turn your ignition switch on for about 10 sec. Then take a small screw driver and push that valve in gas should spray out try to avoid getting it in your eyes ideally wear safety glasses when you do this. If you have a fuel psi gauge that would be the most efficient and safest way to check your fuel system. If you are getting fuel and a spark the only thing left is compression and spark timing. We can be fairly certain that you have compression because it was running. I think it is out of time a little you may even have your wires crossed. I think you said you moved them. Lets start by getting the no 1 up on TDC. This is very critical some people change many parts due to the static timing be off. Sometimes we assume the basic things have been done. So you take out the #1 plug unplug your coil and pull your fuel pump fuse or relay. Have an assistant bump the starter while you have your thumb on the hole of the plug. If you are by yourself you can put an old plug in to an old spark plug wire end. You just cut the wire off and stick the plug in make sure the old wire has the old boot on it because that is what you put in the plug hole. OK so as the engine is coming up on TDC you will feel psi build up and blow off your thumb. Find the mark on your Harmonic balancer if you get it close it is best to turn it by hand to get right on 0. Important! Do not turn it backwards if you pass 0. Just bump it over again until you get it on 0. OK now that we have the #1 cyl. Up on TDC take off your Distributor it should have a 1 on the distributor cap if not just follow your wire from the plug up to the distributor cap. If the wires have been moved then all you need to do is follow these directions. The 3.9 L usually has #1 at about the 9 O clock position. Another way to tell where it is at is the cap hold down screw should be between # 1 and # 6. Now what you need to do is make sure the rotor button is aligned with the notch on the switch plate if it is not perfectly lined up you will need to loosen the hold down bolt on the distributor and slowly rotate the distributor to get the rotor button lined up with the notch on the switch plate which will also align it with the plug on the tower. After that is completed make sure you firing order is right. The firing order is on the intake you will see the numbers stamped on the motor If I am not mistaken it is 1, 6, 5, 4, 3, 2 it rotates clock wise so trace each wire starting with
# 1 then going clock wise follow your wire from your # 6 plug. Plug it into the next tower. Just repeat this process. Cyl. 1, 3 and 5 are on the left side of the engine 2, 4and 6 on the right. Remember when refering to left and right on the engine you should always refer to it as if you are sitting in the drivers seat. Some people just can't get that not saying you are one of those people. But if you have to view it as if you are standing in front of the car looking at the engine then it is just reversed. So looking at the engine Cyl. 1, 3 and 5 are on the right and 2, 4 and 6 are on the left. Viewed from the front of the car. Sorry about all the redundancy. If you have Air, Fire, Fuel and compression you should be running but if you have all those things they must be occurring at the right time.

Good Luck let me know how it goes.

I have a question because my repair book is not very clear on the wiring of the plugs. You said that Cyl. 1 is at 9:00 and it goes Cly. 6, 5, 4, 3, 2 going clockwise. Is Cly. 6 in the 7:00 or 11:00 position?

The cyl. # 6 would be at 11:00 position.
Good Luck

The repair book was not very clear on the cyl wiring diagram. My truck is now up and running. I will drive it over the weekend to see if changing the cam senor made any kind of difference. I also want to drive it to see if the computer needs to sinc the cam and crank shaft sensors up.

Glad to hear the good news. Give me some feed back if you can. Thanks and Good Luck