Runs like crap again P0300 code-hemi 5.7

Discussion in 'Engine & Performance' started by silversides04, Jan 10, 2012.

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  1. silversides04

    silversides04 Junior Member

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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!
     
  2. ramhunter9

    ramhunter9 Supporting Member

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  3. BlackedOutHemi

    BlackedOutHemi Senior Member

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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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  4. 03MopaRamman

    03MopaRamman Senior Member

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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.
     
    Last edited: Jan 10, 2012
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  5. ramhunter9

    ramhunter9 Supporting Member

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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
     
  6. BlackedOutHemi

    BlackedOutHemi Senior Member

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


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  7. silversides04

    silversides04 Junior Member

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    I used the regular plugs not platinum, the stealership put them in less than 5K ago.
     
  8. silversides04

    silversides04 Junior Member

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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!
     
  9. 03MopaRamman

    03MopaRamman Senior Member

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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.
     
  10. bigbadram1500

    bigbadram1500 Administrator Staff Member

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    Welcome to the forum. :) Hope you get it fixed up. Let us know how it goes.
     

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