Runs like crap again P0300 code-hemi 5.7

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silversides04

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I just got this P0300 code 2 days ago(the first time was 3 months ago and they said I needed new plugs so I got it done and CEL disapeared until 3 days ago). Today on a cold start she runs OK for 2-3 minutes and then wham! it runs like crap. 3 days ago it started running very bad while I was 50 miles from home. 3 months ago it started being a little hesitant of the line on a gentle accelerate and when it got over 1000rpm would kick in better. I had plugs and EGR changed recently. The only time it does run proper(tried it today) is when I hammer it to the floor and it runs like it always did-fast and hard! otherwise its barely alive and dies once in a while. Is it possible I have valve spring issue? It's got 168,000km(105K miles) on 5.7L Hemi.
ANY IDEAS GUYS? feel free to ask any questions
thanks!
 

BlackedOutHemi

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He said at the top he just changed them 3 months ago when he had the first problem, so has to be something else.


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03MopaRamman

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I have had this issue on and off for 2 years and finally figured out the Problem.

Dirty Fuel Injectors for Sure.

I have remidied my situation for now using STP Fuel Injector cleaner Bottles run through 4 consecutive tanks in a row while doing 1200 mile Trip. I have not had the P300 in about a month or so. Prior to this I suspected the injectors and would do an STP cycle and about 1000 miles later the light/code would come back.

The light/code will go away on its own to tell you they are working clean again.

I plan on paying the approx $169 for a profesional treatment next time which will yield some long time results but I am pretty sure that is what your problem is and like Dave said check your plugs and maybe replace them anyway.

Another sign of this is white residue on some/not all of your plugs before the 30 K interval.
Seeing the age of your Truck I would recommend changing the PCV Valve and the Map sensor ($50 bucks for both) Also if your wires are stamped 2004 along the leads they are probably weak as well.

Just my 2 cents, Bud. And Welcome to the Forum.
 
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ramhunter9

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He said at the top he just changed them 3 months ago when he had the first problem, so has to be something else.


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What I was trying to get at is .. what plugs ? Did you use the champion copper plugs or some platinum plugs ? Platinum = no good
 

BlackedOutHemi

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I see. And completely agree. Goodluck man! Hope you get it fixed.


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silversides04

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I have read so many different remedies for this issue on many forums and posts, but I will put injector cleaner in. BTW I have been running Chevron 91 for a yr now.
Thanks for advice and the welcome note!
 

03MopaRamman

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You will need to do a Highway Trip and after 200KM you should start to feel improvement and by the end of the first tank your light should go away on its own during a self check. But it takes a couple of Tanks to totally disappear. Don't let it sit in the tank for too long though. And if you fill up before its empty just add more. A 350 Ml Bottle treats up to 80 L so guage for the extra 20L on the first go so like more than one bottle to start. Once your problem is fixed treat it every oil change and if it persists further/comes back after 2000 KM then they require treatment again or have them cleaned Proffessionaly at say Fountaine Tire.

I also fryed a $200 set of NGK Iridiums in the last year and learned my lesson about putting in other than Copper plugs. All along I thought it was related to my Crazy Spartan Cam and Tuning Issues but now realize it was my injectors all along and i too was running 91 Octane Fuel.

BTW my problems started at around 235 K Km (Metric Talkin Eh!).

And please report back your findings on here as I am Pretty Sure it will Help with your Problem.
 

KGBIGCOUNTRY

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Fallow Danny's advise just needs the system cleaned real good.
 

perriott

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dodge ram 5.7 hemi

Hello everybody, am new here. Need some help I just bought a 2005 dodge ram 1500 hemi. I have the same p0300 problem doing the fuel treatment seeing some progress. One question is it normal that my RPM doesn't go over 4000 when in park?
 

Buddys30

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P0305 misfire

Recently I purchased a 2011 Ram 5.7 with 92,000 miles on it and after about two months, got CEL, shaking and loss of power over 3000 rpm. Dealership replaced spark plugs, de-carboned engine, cleaned throttle body and injectors and checked the coil packs. $650 later I was driving down the freeway and same problems occurred; right back to dealership. This time diagnosis was bad cam/ lifters and valves. Fortunately, I had purchased an extended warranty that covered internal engine parts in order to finance a high mileage vehicle. Long story short; dealership still has vehicle ( waiting on back ordered lifters) and reassembly for 4 weeks! At least it will be covered.
 

bhonshell37

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Is anyone monitoring this thread? I could use some help with a misfire code as the title reads.

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stc315

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Posted response on wrong thread. Doh!
 

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