ok so i havent had the time or money to tune up my truck but am doin so this week but i really dont think it due to the tune up..i could be just driveing down the road and it will just start missing and backfiring like hell.it only dose it after dirveing the truck alot and after it cools down to 0 again it will run fine. the sputtering and missing will stop if it give it a little more gas but at 65 thats all the faster the law let me go so if im driveing at a constant speed it misses and backfires.ill put the tune up on it and see but it might be something more seariouse..any help will be helpful not rly a dodge guy love my bowtie duramax but love the dodge look.

 

Bad cap on the distributor. Do the tune-up, see what happens. My guess? It will clear it right up.

 

Check O2 sensors.

 

O2 sensors !!

 

Does this happen only at/around 65MPH, and not at 50? And not at 70? If this is the case I'd strongly suspect the Throttle Position Sensor has got a noisy spot on it.

 

I would pull the dis cap and check and see if the are fured up first. If your running champion plugs pull one and see how they look. the plug will tell the story. for the tune up I use napa wires and ngk v power plugs. Napa caps have never done me wrong except for the funk chevy cap for later 90's . remember you get what up pay for in this case. good luck. I think a bad o2 won't make it miss all by its self.

 

+3 on o2 sensors

 

im not sure id its the o2s ill put the full tune up than check and see if it helps any it dose is at 65 if im steady driveing for a while.. but the thing that gets me is if it ws o2 sensors it would miss all the time or really be bad missing goin on.. its only at constant speeds.and if i give it a little more gas it clears uo so ill let you guys know if it helps with the full tune up it needs done anyways.. but thanks for the help will have more questions later in the month and futcher..

 

My 94 318 has been doing it, like alot of sputtering problems addressed on here. I replaced alot of sensors. I last replaced the engine coolant sensor, and it did not fix it. After looking in every crack and corner of the engine, I found a sensor just behind the altinator. I looked it up and it a
temperature gauge sensor, I replaced that last night and my truck has stopped the sputtering completely. My truck idles perfect, I have gained alot of power. That's funny it takes 2 differant temp sensors, 1 for the engine, and another just for the gauge.
Anyway it is finally solved.