I have a 2003 2500hd. This weekend i took it out in the mud and it started to bogg out. The check engine light started to flash so i knew it was miss firing. I have changed the plugs and wires. The codeP0300says its a 'random/multiple cylinder misfire detected" Any one know what that could be or what else i should try

 

is it still misfiring? you might've just gotten some water in the engine and if you didn't bend a rod you should be good to go now if its running fine

 

As of yesterday it was. I let it set over night and it still misfired

 

You possibly could have messed up one of the coil packs (but I am just guessing). If it is still throwing the code, then I would say that you need to have it diagnosed to which cylinder it is and go from there. Then you will probably need to have the coil changed.Those code readersonly point you in the right direction, from there you must go throught the diagnosis touble shooting list. Basically there is a list of things tocheck and test after there is a diagnostic trouble code thrown. What you find wrong on that list of things to checkis what you will need to replace or repair.

Take for example, if you have an 02 sensorDTC thrown. Now you go down there and replace the 02 sensor becouse that is the problem right? Well maybe not, you also need to trace down the wiring and make sure it is not cracked or burned through on an exhaust pipe for example. In an actual repair manual that would tell you to test the amount of resistance to that sensor and then go to step 2 if it passes. So on and so on! That is the right way to do it, but who really does the right thingnow a days anyways?? Think about it!

Thats what I have to say about that!