I have a 96 Dakota 4x4 auto. I have a miss that can rear it`s ugly head at start up or hide for hours and sometimes a day or two. It did this before and a pick-up coil was at fault. During the process of both problems I changed cap.button,plugs,wires,coil,pick-up coil again.and most of the sensors except for MAP, O2, and crank sensor. I went to parts store for a read out and they couldn`t get it. Is there a way to track the beast or is an expensive trip to the dodge garage in order. I have another 96 with a 6cyl. to experiment with different parts. At one time the code showed up as the O2 but after a reset it doesn`t come back on. If it`s the O2 wouldn`t it do it all the time? Is there a possibility it could be a fuel pump or filter?

 

First do you have a Check Engine Light? You can check it yourself easily. Check the FAQ for instructions and the code list.

Next to find a miss unplug a fuel injector connector one at a time while the engine is running. You wan to see which one does not make any difference in the way it runs.

 

I do have a check engine light and that`s where I get the 21 code for the O2 sensor. I haven`t tried to do the injector yet but I did remove 1 plug wire at a time that really didn`t show much. After Each one was removed it changed the idle.

 

Recheck the work you did for loose connections, etc. Run some sea foam through the next tank of gas, to clean your fuel system. If your fuel pump is good, you'll hear it energize when you turn the key on. On your 96, I believe the fuel filter is in the tank...bummer. Check the connections on your MAP and crank sensor. Does the miss only occur after the truck has run awhile? If so, sounds like something affected by heat...like an electrical connection.

 

If you do the plug wires you can shock your self pretty good. It is safer to do each injector plug.

 

I`ve used a good bit of fuel system cleaner (Lucas) and water remover hoping that was the problem but no change. I`ll go back over what I did and recheck it. The Haynes book I have shows the filter/regular connects to the top of the tank. Heat doesn`t seem to matter. sometimes it does it at startup.

 

did you try unplugging the o2 sensor since that was the code you got?

 

Wouldn`t that just cause the code to stay in there? That`s how I checked the MAP sensor. When it was running I unplugged it and it showed on the next code check.

 

Just a quick update. After rechecking the work I did I found nothing. Then after moving a vacuum hose on front of the throttle body I caught a break. O very small crack in the plastic part. Changed it out and it`s much better. It still wants to miss on cold takeoff but levels out and runs OK. When checking the code with the switch I get 3 21 codes consecutive. It`s the O2 code. Guess I`ll take it to a proffesional to figure it out.

 

Put some penetrating oil on the sensor when the truck engine is cold, then start it and let it warm up for a bit...more oil, then pull the sensor...it could be pretty ragged if it is stock.