03 dodge ram 5.9 gasser blows black smoke under heavy acceleration?

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mcCraw

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Charleston,sc
Ram Year
2003
Engine
5.9
ok so i bought this truck used its got the cat removed true dual setup im not getting any codes relating to this and horrible gas miliage what is causing this ? thx
 

ramhunter9

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P-Star Jeep Wrangler
Um ... its a 5.9 V8 Magnum ...LOL

Welcome to Ramforum .

Want better MPG'S ... tuner , CAI , full tune up .

But dont expect to get over 15 with that beast .

Black smoke could be a few things ... gummed up . To rich .. ect ... just tel guys you have a cummins LOL

Im sure more 5.9 guys will chime in

Again welcome to the forum
 

adamwilkes14

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Do you get a faint gas smell when the engine is idling? Are you still running your O2's
 

adamwilkes14

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Yeah, reason why I say the O2's is, if the PCM is not getting info for them, it could just be dumping fuel into the engine, causing the black smoke. How do your spark plugs look? Are they carboned up?
 

ramhunter9

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^^ that is why I thought it was running to rich ... good call Adam
 

wermbang

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Iowa
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2001 Off Road
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5.9L V8 Sport
Welcome to the site!

Yeah check whats stated above.

The 5.9 is no mileage queen. I am getting 12 with a Superchips, Catback exhaust, and a CAI. I also have a 4:10 rear so that hurts it a bit too.
 

txbass06

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NE Texas
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1996
Engine
5.9 Magnum
I wish I was getting 15 lol. I'm getting just under 11 with 35's, cai, and 3.55's


Sent from my iPhone 4 using Tapatalk
 

talon6

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Location
ohio
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2002 QCSB 4X4
Engine
supercharged 5.9
plenum gasket needs replaced.

and with my mods i average about 10mpg.
 

nim81

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5.7L
+1 on replacing plenum gasket
Hughes make a great replacement kit that will fix the problem

I've owned 2 5.9 magnums and a 5.2 magnum and have had to replace the plenum on all 3. Also keep a close eye on your oil level cause with the plenum leaking oil into your intake manifold it will run out fairly quick!


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BlackMagnum2000

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Agreed on 5.9s not being good on mileage. I'm getting less than 7 now. On a essentially brand new engine with intake exhaust and an economy tune.
 
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