I have a 99 dodge 3500 van...had a reman.motor installed about 5 months ago..started having issues with aftermarket coils burning up..went thru 3....installed a mopar coil..so far so good..but motor will sometimes start missing to the point engine dies...sometimes check engine light will come on..had that checked..code is saying # 8 cylinder mis-fire..but then the light will go off..took it back to shop..they say oxygen sensor is bad...they replace oxygen sensor..runs fine for a day or 2..then the miss and die is back..light comes back on..today light is back off and it run fine...its driving me insane....so my thinking is this..#1 computer??? maybe alternator??? something electrical..or ...I now own a van posessed by satan...any insight at all would be greatly appreciated. steve

 

If you're only getting a misfire code on #8 then I'd say the problem is isolated to that one cylinder. This eliminates things like the crank and cam sensors, cap & rotor, and the computer as the likely culprits. I'd focus on a bad spark plug, plug wire, or fuel injector on the #8 cylinder. You can try swapping each of these components with another cylinder one at a time to see when the problem also switches to the other cylinder. Once the problem switches, you've found the bad part.

 

well the problem with that is it only has this miss thing at random times..and the check engine light also comes up randomly..I mean the light will come on when the engines not even having a problem..or at least I dont think it is having a problem

 

There are other factors (or a combination of) that can contribute to a random behavior. Hot or cold engine, rainy or dry out, vibration making or breaking a loose connection, an intermittently working sensor, just to name a few. The misfire code can be set without you feeling it because the code only needs a 1-2% misfire rate to be set. The code also needs to be triggered on two consecutive trips before the light will turn on.

 

Maybe a possible bad injector????

 

thought about that..but would an injector be that random??? it has ran fine for about a week and now today back to the same miss and die at a stop

 

With a puzzled thought in my mind ... Does the cap-n-rotor have aluminum contacts or copper/brass?

The reason I ask is because the aluminum contracts are pure junk. Some little inexpensive part could be the culprit to your problem.

Years back a vehicle of mine had a miss and seemed to be bad cylinder. (1992 Plymonth Acclaim) After going crasy looking for the problem, I have stumbled upon the cap-n-rotor while looking at everyting. Those contacts looked great except for the number 3 cylinder. That contact was worn like the rest, but the aluminum was flaking off of that contact. When I had replace the cap-n-rotor with a new copper/brass type, the problem of the number three cylinder and missing totally went away.

It's just a thought to check it out.