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Unread 05-03-2014, 07:47 PM   #1
agony691
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Wj Rough idle black smoke

kk, i have a 4.7 wj 2000, w/206000 miles. Its idling rough... i mean rough.
I have tried a new tps, seafoam in the vacuum line in the gas and in the oil to no effect, replaced all the injectors. also it has overheated twice bad water pump (replaced). im thinking coil pack .... but they are expensive so trying to make sure before i buy.... HELLLLP!!!

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Unread 05-03-2014, 08:17 PM   #2
Justindbrooks92
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Try used coil packs.. Craigslist is awesome if you know the jeep ran fine before than the new coils should still work for yours if that's the problem
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Unread 05-03-2014, 08:44 PM   #3
gold01wj
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Quote:
Originally Posted by agony691 View Post
kk, i have a 4.7 wj 2000, w/206000 miles. Its idling rough... i mean rough. also it has overheated twice bad water pump (replaced).
How's the head gaskets... 4.7s don't like overheating...although blown head gaskets don't often produce black smoke (usually white) that has my attention...
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Unread 05-03-2014, 09:31 PM   #4
PirateB
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Black smoke indicates rich condition. Head gasket usually white-sweet smell from the exhaust.

Why do you suspect coil packs? I'm sure you could test them with a multimeter. Have you looked at the plugs for signs of coolant or oil? Oil in the coolant, or vice versa?

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Unread 05-03-2014, 09:39 PM   #5
gold01wj
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Thus the reason I said a blown head gasket produces white smoke... I was alluding to the not so great history the 4.7s have with overheating... If It were me I'd be keeping a close eye on that especially being it happened more than once.
Op do you have any codes present?
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Unread 05-04-2014, 02:45 AM   #6
MadderThanMax
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O2 Sensors!! & TPS....
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Unread 05-04-2014, 07:47 AM   #7
agony691
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Had a loss of tps signal code gotta new one, cleared the codes. that code has not returned as yet. no white smoke at all no coolant in oil.
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Unread 05-04-2014, 08:37 AM   #8
MadderThanMax
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Still Black Smoke??
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Unread 05-04-2014, 04:44 PM   #9
agony691
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yep still black smoke, and a idle so rough that the truck might shake apart.
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Unread 05-04-2014, 04:48 PM   #10
MadderThanMax
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Video Please??
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Unread 05-04-2014, 07:26 PM   #11
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If it were me, I would start with cheap stuff first and move on from there. Maybe check for fouled plugs first. I cant be 100% sure, but I would think if a coil was bad it would show a misfire via a trouble code. However if you had bad plugs I dont think that would show. You should know that using seafoam in the vacuum line has been known to foul plugs. I always change my plugs after running it through the vacuum line (intake manifold)


This is what I would do first (this is assuming your plugs arent brand new, if they are skip the new plug part). Go to nearest auto place and rent a compression checker (they are free by me, just leave a deposit in case you lose it). Get new plugs and take the old ones out one at a time. Before putting the new one in check the compression of that cylinder. Compare the #s and you also just eliminated 1 piece of the ignition. I would say if you had a misfire, you could see what cylinder it was from via the code and then swap the coil with a known good cylinder and see if the code changes. In my experience the coils on these engines are pretty reliable. However if you need some, I believe the 3.7 in the liberties and dakota and ram use the same coil.
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Unread 05-05-2014, 12:15 AM   #12
bradywgn71
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Change your fuel filter above the rear axle (~$30). It is also the fuel pressure regulator. Chances are the fuel pressure is sky high. After that, change your oil because it is probably thinned out with all the extra fuel being pumped into the cylinders. If you don't change the oil, you can destroy your engine bearings. Pull your oil dipstick and sniff it for gas fumes.
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Unread 05-05-2014, 04:52 AM   #13
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The black smoke indicates that the fuel isn't burning efficiently. The engine is choking off and not getting enough air. Last time you changed the air filter? Is the air box clean free of debris? Any vacuum lines plugged or kinked? Any codes? Likely this is not a coil problem unless you can confirm a genuine misfire condition and even then what happens is that the unburned fuel gets pushed into the CAT and you would have a fuel odor and not black smoke. Could be O2 sensors but I would look for the simpler items first and if you can check for codes or pending codes.
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Unread 05-06-2014, 09:51 AM   #14
agony691
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I bought a code scanner will update shortly
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Unread 05-12-2014, 07:07 PM   #15
agony691
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ok got my scanner today, im getting a p0202 error on cylinder 2, so i changed that injector cleared the code.... ran it code came back. i cant see any corrosion on the cable but... cant be sure. Suggestions?
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