# 2004 Dodge Ram Mass Missfire Help???



## habart30

My 2004 Dodge Ram 2500 5.7 Hemi suddenly started idling very rough. It won't idle by itself unless your giving it 2-3 RPM's worth of gas. Took it in for a Diagnostic and the code was T0300. They think it needs a compression test with a possibility of a broken valve spring/springs, but wanted to charge me $300 more to do that. It's not knocking or ticking, so that leads me to believe it's more of a fuel problem, or possibly the coil pack. The mechanics that ran the Diagnostic said the spark plugs were fine, and ruled out the possibility of a bad fuel pump or injector.

Any help would be much appreciated..thanks!


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## sweetk30

i do know the hemi enggines like only the oem plugs when tune up is done. and dont forget there is 16 plugs. and to get to the back 3 on the driverside thay say remove the brake booster. but if you got time and few extra 1" long extensions it can be done with socket in hole then drop in each extension and remove in same order. 

p300 is random miss fire detected. could be plugs or coild be a coil or 2 dropin out bad. 

would need scanner to find out what cyl's are dropin out on missfire counter padge to help pin point the problem. i am suprised thay didnt do that test its super easy. unless thay had a code reader only computer scanner.


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## habart30

yeah I don't think the plugs are OEM. I just bought this truck 4 months ago.


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## sweetk30

seen a few hemi's with non factory plugs run with skips and not right. 

swap them to factory replacement plugs and bam all gone. and the plugs we pulled out were like new just not champion and # correct. 

even seen this in chevys with 305-350 vortec motors 96-2000. my own truck even . skip under load on highway with od in and locked convortor. swap back to stock acdelco and gone. 

todays computer controled stuff is super sensitive to changes in the whole system.


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## RacingZR

Yep, probably time for a tuneup anyway. Do all 16 plugs and see if you still have a problem.


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## Green Grass

knowing the year of the truck there are good odds that you broke a valve spring. They have updated valve springs for the trucks.


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## plowguy43

2003 was the year for the bad valve springs. I agree with the plugs just plain jane non platium plugs are what the HEMI likes.


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## Green Grass

plowguy43;1179754 said:


> 2003 was the year for the bad valve springs. I agree with the plugs just plain jane non platium plugs are what the HEMI likes.


2003 and early built 2004 had valve spring issues. Compression test would tell you if they are bad.


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## habart30

Found out today I have a broken Valve Spring in cylinder 4. Both spark plugs in cylinder 4 were black, all the others were fine. Also has a split coil.


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## habart30

Got her up and running today thanks to a good buddy of mine. He had it diagnosed yesterday, got all the parts for very cheap, and had it fixed today by 2pm. Just in time to plow!!!


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## silversides04

*2004 ram 1500(5.7) error P0300*

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 code disapeared for a while). On a cold start she runs OK for 2-3 minutes and then wham! it runs like crap. 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 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!


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## Green Grass

They are known for breaking valve springs and have a revised valve spring


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## silversides04

Green Grass;1410908 said:


> They are known for breaking valve springs and have a revised valve spring


what are telltale signs that a spring is broken? and is there a service bulletin for it?
thanks


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## getsum

had the same problem with my last dodge. needed a tune and i had broken valve springs... $900.00+ fix at dealer. had the same problem, sounded like i had a huge cam in the truck lol


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## silversides04

getsum;1411236 said:


> had the same problem with my last dodge. needed a tune and i had broken valve springs... $900.00+ fix at dealer. had the same problem, sounded like i had a huge cam in the truck lol


My truck doesnt sound like big cam, sounds the same as when i bought it. the problem is intermittent but is getting worse.


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## Green Grass

silversides04;1411470 said:


> My truck doesnt sound like big cam, sounds the same as when i bought it. the problem is intermittent but is getting worse.


check compression to check for broken valve spring or remove valve cover and inspect. another possibility would be an o2 sensor cause they are not monitiored on start up for a couple min and on wide open throttle they are not monitiored.


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## silversides04

O2 sensor sounds like a likely problem, I'll check asap. thanks


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