Hey guys, I got a 2001 Dodge 2500 4x2 with about 115,000 miles. It has the 5.9L 360 gas. I need help diagnosing my misfires. I have had it in for both compression and vacuum tests and they came back good. I replaced the plugs, wires, cap and rotor and also had the injectors cleaned. The side effects so far have been a severe lack of power, bad acceleration, terrible mpg's (about 9 miles/gal), and a pretty subtle shake as it idles, easily seen through my antenna. When i ran an OBD2 it also said i had a small and large evaporation leak. It is also fairly easy to hear through the exhaust if you know what your listening for. I was thinking it might have something to do with the fuel pump because i have had a couple of challenging starts the last couple days. Otherwise it is one of the fastest starting vehicles I've been in. Really would appreciate the help. Thanks

I also plan to run another test so i can figure out which cylinders exactly and i will make sure to put that up asap

 

For the Evap leak, make sure the gas cap is seaking. I had the same codes and that all it was.

As far as the miss, are the plug wires routred per the TSB? Also, for the cap, its recommended to go with brass terminals. Plugs, $2 basics; Champion, NGK seam to be the better ones. 9 mpg is not that far off either.

 

Hey thanks for the help kejobe. Im not sure what per tsb is sorry but i can tell you that i got the premium plugs and wires that oreillys offers. I can also say they are gapped right and the firing order for the wires if correct. Im pretty sure i bought the brass rotor also but i just got the best one that oreillys has again so im not pos. Funny thing is, now that I unplugged my battery the check engine light has gone off and has not come back on for about a week now??? Goofy? As for the gas cap, i was sure that would fix the leak too, when i bought a new one, and it did....... for about a month or two and now it came back with a large and a small leak. I love this truck but so far nothing but small issues that are very annoying to figure out. Again thanks for the help everyone, anything would help to figure this out. I don't have the money for $100 repetitive diagnostics, enough is enough hahaha

 

Check to make sure none of your spark plug wires are burnt through laying on your headers or anything.. Take it from me.. Lol

 

Blown plenum gasket, bad o2 sensors and clogging cat. https://dodgeforum.com/forum/2nd-gen...um-thread.html


And here is the TSB for sparkplug wire routing. http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

 

Thanks tatitup8 I went out and checked just to make sure, but unfortunately for me its not that easy. They all looked fine, but i really appreciate the time to help.
ZMAN17- Thanks for the info. I'm now thinking that it is most likely the o2 sensors or a clogged cat. I did a little reading into both of these and they sound like a pinpoint to the problems I've been dealing with. As far as the plenum gasket, I'm going to check and see if there is film build up in there but I really hope not lol I watched a few youtube vids and it looks like a real pain in the ***. Im going to be running out to run an obd2 again on my truck tonight around 7ish so hopefully I can get a better understanding of what is going on. I really appreciate the help guys and I will be posting the codes a little later when I get back.

Another question- Earlier today I replaced my thermostat but when I did i splashed some coolant into by butterflys. Thanks to dodge the air intake all has to come off to get to the thermostat and by placing it the way they do which is verticle on my truck with a goofy extension pipe for the hose, it makes it hard to be neat about things. Anyway the coolant splashed in but i think i managed to get it all up before i opened put it back together and the butterflies were opened. Would a small drop getting in do anything?

 

It might smell funny for a few minutes, but that's it.

 

I don't think a tiny bit of antifreeze would do anything.

Also with the gas cap, I kept getting the codes even after a new cap was put on. What I did and has been good for 8-10 months now is I put a little vaccuum grease on the seal. You can also use petrolium jelly (Vasiline).

With the plugs, a lot of these trucks don't like the "best" plug. There is a lot of info. in the DIY, Tech section, including a thread on plugs. That will give you a better idea on them.

 

After chasing the plug wires, plugs, rotor, cap and coil we run to the others. Tps, dirty throttle body, blown plenum gasket,evap canister purge solenoid and bad connection at ecu.
I went through all the garbage and money only to find that on closer inspection my rotor top (where it contacts middle of cap or coil feed) was for some reason loose. Grrrrrrr. Good luck, missfires can be like chasing ghosts!

 

Yea i know what you mean moparman, this has been an ongoing situation/investigation for months now haha grrrrrr is right. Im taking my time and going the cheap route tho but not on parts just labor.

*NEW PROBLEM*
Truck doesnt seem to building up pressure upon acceleration from stop. RPM's rev high but the truck hardly wants to go, still does but slowly. Gets better a couple seconds into getting going. If i let it worm up longer or sit and run for a minute this prob seems to go away. Hmmmmm....... Fuel pressure regulator??? Would this cause misfire???????

I ran another OBD2 and found that I now only have 1 misfire and solenoids out in my transmission which i knew about.

CODES-

*P0305- Cylinder 5 misfire
*P1740- Trans solenoid
*P1740- Trans solenoid

Also went through and firing order was good but my plug gaps were .045 to .046" instead of the recommended .040. Not sure it this is bad but i replaced them all anyway with the exact .040 champion coppers, factory recommended. As far as the wires, they all look good and are not showing sparks in the dark, boots seem find but i have noticed there a little looser than i feel comfortable with. They grab the plug just fine but the the boot itself seems a little sloppy and has to much play. I am running 7mm premium silicone Super Max core 10's. Anyway one of my buddies told me he was pretty sure there was a very common cylinder 5 misfire with the dodge 360, so i thought what a better place to find out than a bunch of dodge owners and/or enthusiasts. Thanks for all the help guys, this forum is awesome. Should also say that at idle with the new plugs it seems to run a little smoother but lack of power and pep is still very obvious. Not sure where the evap system leaks went either haha.