1500 Running rough after new plugs

bzn · Jul 29, 2017

My 1998 RAM 1500 5.9l is running rough after I replaced the plugs. I thought it needed some TLC and replaced plugs. The wires (probably original) pulled the connectors out. So, I replaced wires also.

NOW, the truck runs worse than ever. Seems to be misfiring and Check Engine Light is blinking.

SOOO..I replaced all the plugs with Autolite double platinum. Runs a little beter but she still runs rough.

I 'm thinking bad set of wires.

The truck was running okay until I decided to fix it.

Any ideas where to go here?

Burla · Jul 29, 2017

What code are you getting?

BigSloth · Jul 29, 2017

Check your firing order on your plug wires. I'd put money on the problem being that you have 2 of them reversed.

huntergreen · Jul 29, 2017

You need to have the codes checked. Does your 98 have the turn key on and off x3 to pull codes?

07MegaCabRam · Jul 29, 2017

Double Plats run like crap in the 5.9. Really hot.

What are codes you pulling?

Ram Night · Jul 30, 2017

I have ran the 5.9 engine in a few different autos, and I have found that Champion plugs are your best bet. And check your firing order to make sure there is not two wires in the wrong location in the distributor cap.
And check the distributor shaft bearing to see if you can move the rotor around. I had a 440 that was running rough and I had a worn bearing in the distributor. I replaced the whole unit, and the Cuda ran great after that.

fastf · Jul 30, 2017

Ram Night is right you don't need fancy plugs for the 5.9 Champions are the ones and start checking your wires you may have on crossed.

Yeret · Jul 30, 2017

Those double platinum plugs are your problem. Platinum has less conductivity than copper but is much more durable against heat. As a result, they last longer but require more power in order to reliably fire. As such, platinum and especially iridium plugs require a hot ignition coil to work.

Our ignition coils are relatively "cold." As a result, platinum-coated firing tips won't fire very well, if at all. Bare copper firing tips should only be used with OEM-spec coil. Many, many people have tried platinum plugs in the Magnum engine because the parts store guys says they're better (but never actually gives any reason), and then wonder why the engine runs like crap with new plugs.

Champions have always worked well for me. I'm currently using NGK with a slightly cooler heat range at the suggestion of my tuner. People have also had luck with Autolite 3923.

Also, blinking CEL means you've got a very bad misfire. A cylinder isn't just misfiring occasionally, it's misfiring almost every cycle. This results in a lot of raw gas going through the exhaust which will almost certainly combust upon reaching the catalytic converter, which will quickly destroy it.

dodge dude94 · Jul 30, 2017

Dropped 3923s here. Runs great.

Route your wires per the TSB on ignition wire crosstalk, and ditch the double-platinum plugs.

anthony2558 · Jul 30, 2017

How about checking the gap?

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dapepper9 · Jul 30, 2017

dodge dude94 said:
Dropped 3923s here. Runs great.

Route your wires per the TSB on ignition wire crosstalk, and ditch the double-platinum plugs.

This

1500 Running rough after new plugs

bzn

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Burla

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BigSloth

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huntergreen

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07MegaCabRam

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Ram Night

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fastf

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Yeret

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dodge dude94

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anthony2558

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dapepper9

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