Was driving home from work today up the highway. My truck did the usual cough it does till the thermastat opens..(can't seem to figure out why it does it) But today a few seconds later the CEL came on flashing? I hooked my scanner to it to see what code it was. I had a p0300 random misfire code plus 7 others which were a code for every cylinder 1-8 p0300-p0308. drove less than 3 miles and it seemed to do the caugh again and the light went out???? Anyone else ever encounter anything like this, or have a thought? I know it's not a clogged cat. Since it dont have one. Iv'e put plugs, cap, rotor on within the last 300miles. Ohmed out the injectors, MAP sensor and TPS as well as the IAT and they were all ok. seafoamed the intake through the brake booster vac. line. and also cleaned the TB with carb cleaner as best I could with out removing it. Also recently replaced the Crank pos. sensor with an aftermarket one BWD brand.

 

I would point at that pos. crank sensor, dodges dont seem to like aftermarket sensors in important places (BWD does tend to make good stuff though). Cant figure why it would make it misfire like that, but its worth a shot. Hows fuel pressure? Did you test/replace the coil along with cap/rotor? What temp were you at when this happened? If it was at/close to operating temp, it could be front o2 sensor related. Try unplugging it and see what it does. If it runs better without it, its time for a new o2.

If you have access to a shop with a more sophisticated scanner, it can pull up the pending CEL's that havent turned on an idiot light yet, might offer some more insight to your problem.

edit: Its a longshot, but ECT sensor could have something to do with it. Ran into issues similar to what youre experiencing a little while ago and the ECT was to blame. I think that would give you more noticeable symptoms though (temp guage went apesh!t on mine, and set a different CEL), but its possible

 

Check the cam sensor for damage and whether or not the connectors are tight, dirty or greasy. Your problem lies in what all you changed, especially the sensor noted in the above post.

Check the plug wires for proper routing, etc.

 

The aforementioned sensor would be my first guess, or, possibly the ignition coil.....

When mine did that trick, it was actually the cap that was the problem. Changing the coil fixed it for a couple days, and that was it..... but... yours is fairly recent. Where did you get it at?

 

Thanks for the input guys. Mad_Scientist: I had some freeze frame data on my scanner that said the engine temp was 79deg. its about 35 outside today. I do have a pending evap code. p0420 or p0402 evap emissions leak (very small). Fuel pressure I havent tested yet. What is the ECT sensor? The weirdest thing with this truck is once the thermastat opens the truck seems to run fine.

VWandDodge: I followed the service bulletin on the plug wires when I did the cap and rotor. While i had the cap off i pulled the cam sensor out and it looked ok no obvious signs of anything. all my plugs have a clear grease on them. assuming a di-electric grease. I was suspecting the crank sensor since i read in another post that a guy replaced his with aftermarket and his truck would idle for about 8-10 minutes then just shut off. Turn the key and start it right back up. Mine will do that on occasion as well.

This just in: Requested build sheet from chrysler on my truck. just got it a few minutes ago. States that the engine from factory is a 5.2L. the dips$%t I purchased the truck from told me it had a 5.9L engine in it and it had been replaced with another 5.9L engine out of a 99. He doesn't however know if the computer was changed. However if the computer was the issue, would it run good when the engine was warmed up. But not when it's cold. SO FRUSTRATED WITH THIS TRUCK!

 

Cap and rotor are BWD from advanced autoparts. does have copper or brass terminals. I do know the jacka$$ that i bought it from had the coil just barely hanging on with one bolt.

 

Yeah.... I would be lookin' real hard at that sensor......

 

has it always ran strange when cool? The reason I ask: when it's in open loop it runs off of tables coded into the PCM- when the loop closes, it can run off of real time data from your o2 sensors and such- and trim fuel, advance/retard spark.. If that PCM isn't the PCM you're supposed to have, or if it hasn't been programmed correctly, that could be contributing to your weirdness before closed loop.. If I'm off point here, I'm sure the smarter guys around will correct me..

As far as the rest of your issue- I'm with others as well.. CPS.

 

Taking into account that your truck was at 79* when this happened, we can eliminate the o2, it wasnt hot enough to warrant the pcm going to closed loop, and thus, the o2 is discarded from the equation.

As for the pcm not being correct: drewactual hits on an interesting point, however, i think it would have given you more interesting problems by now (not sure a 5.2 pcm will run a 5.9)

Your evap system doesnt come into play on the ignition timing or a/f ratio being off (which is likely what happened in your case), and is a completely separate problem (it can put the truck into limp mode though, had a fun time with that myself).

I have been told that a loose gas cap can register as a small leak. If that doesnt fix it, do this: Check all the evap lines for a leak (very tedious) or have a mechanic run a smoke test (easy, but am not sure of the cost). An evap problem can make it run like **** but it shouldnt cause misfires (the extremely large leak i had didnt anyway)

ECT: engine coolant temp. Mine was behind (and below) the alternator, but I think your truck is equipped with both a sensor, and a sendor (dodge changed to one sensor at some point, not sure when) I'm not sure where yours are located.

My problem with this sensor was much more pronounced (ECT shorted itself, making the pcm think it was running hotter than it was, causing it to meter a/f ratio differently, and killing the truck) it was due to the pigtail being loose and shorted somehow.

At this point I'm going to point (with 2 fingers) at the sensor vw suggested(cam position sensor), and the one I suggested earlier (crank position sensor). (switches to one finger) A pcm reflash might be in order if drewactuals beliefs are correct

Edit:Oh yeah, and maybe the coil (half a finger)

Good Luck

 

drewactual: I purchased the truck about a month ago. As long as i had it it has had the cold miss, pop, caugh the whole time till it opens the thermastat then it runs like a champ.

Mad_Scientist: my bad on the ETC. I did replace that. Actually both of them. the one for the gage and the one for the ecm. the gage didnt work when i got it since it was not hooked up. the intake only had provisions for one temp sensor. so I drilled and tapped a second one for the gage.


I made a mistake with the evap code i have. Its a p0456 evap code. and as far as the motor. I now believe the motor is a 318. I havent found an engine id chart yet, but the number on the driver side of the block is 58006714-31823. seeing the 318 part makes me think 5.2. when I purchased the crank sensor I bought it for a 5.9L engine. soooo that may be a prob.