P0300 on startup

[djhartm]

Hello all!

I have a 2014 Limited 1500 with the 5.7L.

I have a Hemifever tune and a few other mods, but generally have seen very light duty.

Always have run Mobil 1 & changed the oil & filter long before the DIC says to.

With 53k miles on her, I began getting the P0300.

After clearing it goes away, usually for a few days, then shortly after startup, it will return.

No other symptoms.

Sean @hemifever said it could be the start of the MDS lifter failure.

I get no other specific codes (i.e. P030x).

Not sure where to begin troubleshooting.

I did a cursory check for intake leaks but found none.

Any thoughts\suggestions welcome.

 

[Burla]

It might not be fatal, like you said it hasn't nailed down specific cylinder. I would say switch coil packs and see if it travels, but you can't because you don't have a specific cylinder reading for the mis fire yet. Keep running codes until you do.

 

[Burla]

Just c&p the long possibilities. So no rough idle, I'd say you are a ways off from being able to say it is lifter/cam, but surely it is possible as we know.

• Faulty spark plug (s)
• Faulty ignition coil (s)
• Clogged or faulty fuel injector (s)
• Intake air leak
• Fuel injectors harness is open or shorted
• Fuel Injectors circuit poor electrical connection
• Ignition coils harness is open or shorted
• Ignition coils circuit poor electrical connection
• Insufficient cylinders compression
• Incorrect fuel pressure

 

[H1Chester]

Watching thread!

Nearly the same exact thing happening to me. Second code on start up in about a month. 2015 5.7, just hit 45k miles. No racing, highway city driving, occasional "pull". Also have the HEMIFever tune... Cleared the code and reloaded the tune. Fingers crossed.

Edit: also wanted to say that it also happened on start up. No rough idle or missing...

 

[Tach_tech]

There was a software update for 2013-2015 DS trucks for a bunch of issues, one of them was for P0300.

 

[djhartm]

^My 2014 had all affected updates\recalls recently applied.

 

[H1Chester]

There was a software update for 2013-2015 DS trucks for a bunch of issues, one of them was for P0300.

When did this recall come out? I was not aware of another recent one. Last one I got was the tailgate latch recall. mopar.com says I'm all caught up.

I don't think it is a software issue though. I had a little rough first start this morning, no light or code. Second start leaving the store was much better and normal.

 

[djhartm]

Mine has the same symptoms.

Occasional rough cold start & P0300 thrown, especially if sitting for a while.

No issues once warmed up or after ~10-30 seconds.

I just keep clearing it with my Trinity.

 

[Tach_tech]

It wasn’t a recall, just a TSB. So it wouldn’t be done unless a customer came in with a problem that was covered in the TSB. It came out Feb of 2017.

 

[djhartm]

My battery is at 12.07V sitting. I read this can cause P0300. It's the original battery - 7 yrs old.