Need help! Rough idle and poor mileage

[KyleJP]

Hello, So I’ve got an 09’ 1500 Laramie with the 5.7 Hemi. My check engine light has come on and I noticed that my truck has also started to rough idle, not all the time though, and my gas mileage has gone down about 2-3 Mpg. I checked the OBD and it said multiple misfires on multiple cylinders and the corrective action is the change the Spark Plugs and ignition coils. I have got brand new Plugs and Coils and it hasn’t fixed anything and the OBD still says the same thing. So I figured what the heck and changed the 02 sensors while I was at it. No results. I’m going to have to take it in to a shop but I’m wondering if I can get any feedback on what the possible problem is. Thanks!

 

[Ramitiner]

Did you double check the gap on the new plugs? Did you go OEM on plugs and coil or aftermarket?

 

[17CrewCab1500]

Did you use COPPER plugs? OEM plugs?

What you describe is basically plugs that need to be changed. First thing to go is the MPG.

Hemi's do not like or want high performance plugs. Engineers want a cooler range plug, so if you replaced them with aftermarket plats etc, that too can make the truck run like crap. Seen it a few times!

 

[KyleJP]

Did you double check the gap on the new plugs? Did you go OEM on plugs and coil or aftermarket?

I put new Champion copper plugs in there. And I had double checked the gap on them before I put them in.

 

[KyleJP]

Did you use COPPER plugs? OEM plugs?

What you describe is basically plugs that need to be changed. First thing to go is the MPG.

Hemi's do not like or want high performance plugs. Engineers want a cooler range plug, so if you replaced them with aftermarket plats etc, that too can make the truck run like crap. Seen it a few times!

I put new Champion Copper Plugs in.

 

[Ramnewbie]

How long has it been since you've done any fuel system maintenance? Run a can of sea foam thru you're tank and you might need to clean you're plenum also, especially if you're not running a catch can.

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[Casper]

How long has it been since you've done any fuel system maintenance? Run a can of sea foam thru you're tank and you might need to clean you're plenum also, especially if you're not running a catch can.

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I'd suggest Seafoam through the intake and a PEA fuel/injector cleaner through your tank, not seafoam. That's sacrilege I know, but some folks accuse Seafoam of sludging-up fuel filters. The Ram's fuel filter is in the tank and if it gunks up, its a pita to replace. The jury is out for me, but Seafoam does such a good job for me through the intake system, I can let someone else have the glory for cleaning injectors. I get Techron by the case from the warehouse store, even though there are better regarded products out there, which makes it easy to have around and remember to add frequently.

 

[Ramnewbie]

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I'd suggest Seafoam through the intake and a PEA fuel/injector cleaner through your tank, not seafoam. That's sacrilege I know, but some folks accuse Seafoam of sludging-up fuel filters. The Ram's fuel filter is in the tank and if it gunks up, its a pita to replace. The jury is out for me, but it Seafoam does such a good job for me through the intake system, I can let someone else have the glory for cleaning injectors. I get Techron by the case from the warehouse store, even though there are better regarded products out there, which makes it easy to have around and remember to add frequently.

Yeah, I was just thinking something he could grab easily. Redline S1 and Amsoil pi has the highest concentration of pea I think, one version of gumout is pretty good too. Lucas deep clean has pea but not all that strong.

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