P0300 code on my 03 2500 5.7

[mrmudd]

Changed plugs ,wires and changed crank shaft positioning sensor, and tested all injectors and all tested good. Any ideas, and how test coil packs.

 

[17CrewCab1500]

You most likely have a bad ECU.

With the P0300 is a random thing. If it was say P0301 it would be cylinder 1. P0302, cylinder 2 and so on.

I just had to swap out my wifes ECU on her 2006 Dodge Durango because of this.

I went to carcomputerexchange.com and got mine for $200. Took maybe 30 mins and no more message.

Make sure with your motor, you are using FACTORY CHAMPION SPARK PLUGS!!!

 

[mrmudd]

How did it run before replacing the ECU? My truck runs rough and intermittently acts like it's going to stall.

 

[Marley]

PO300 code will make you pull your hair out, constantly throwing parts at it......until you get an ECU.

At least I have all new parts.

 

[Fast69Mopar]

The real next step would be to get a scan tool hooked up so you can see the actual misfire monitor. P0300 can be a pain especially when the PCM doesn't set any other cylinder misfire DTC's.

Do you feel the engine missing while under a load like accelerating from a standing stop?

How about if you put the trans in drive, set the parking brake and perform a stall test. Do you feel it missing here?

Has this motor ever been apart? Cylinder Heads ever been off?
Do you hears the lifters tapping?

 

[Fast69Mopar]

I also forgot to add something to my earlier post.

You said you changed the plugs and wires.

What spark plug did you put in this motor? Did you take the parts store recommendation or did you ask for a specific spark plug by part number?

Did you happen to put a platinum or iridium type plug in this motor?

Did you change the plugs, wires and crank sensor because of the P0300 DTC or did the P0300 set after the install?

Did you follow a diagram to remove and replace the plug wires? Have you verfied that they are attached to the correct coils and their corresponding cylinders on the other bank?

 

[mrmudd]

Used the plugs they said were recomended for the vehicle. Changed crank sensor and wires due to code. Drew my own diagram before disconnecting the wires. They are installed correct. I also checked fuel injectors and they checked out.

 

[Fast69Mopar]

Alot of parts stores will recommend a platinum plug or an iridium plug for the 5.7 HEMI.

Did you have the P0300 before you changed the plugs? Did you actually have a misfire on any cylinder? How many miles were on the plugs and wires that were in the motor?

5.7 HEMI's come with a copper plug for a reason. I have seen too many 5.7's come in the shop with a P0300 only to find a platinum plug was recently installed.

 

[mrmudd]

Code before everything was changed. There was over a 100,000 miles on plug and wires. Acted better after changing everything. Use to act like it was going to stall after a couple minutes of idling. Now it acts up after driving about 5-10 miles(like it's going to stall).

 

[mrmudd]

Also changed out exhaust system including catalytic converter and both sensors.

 

[mrmudd]

That seems to be when the trouble started.

 

[17CrewCab1500]

How did it run before replacing the ECU? My truck runs rough and intermittently acts like it's going to stall.

It ran rough, idled rough, stalled at times for no reason.
Runs like a champ now.

Also, try this. Reset your computer. Unplug the battery for a good 30 mins.