1999 Dodge Truck rough idle

Tiny
MOPAR123
  • MEMBER
  • 1999 DODGE TRUCK
  • V8
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
My trucks when setting at an idle run very ruff it sounds like it is missing but it is not throwing any codes, I have replaced the entire ignition system and both O2 sensors but the symptoms are still there. The truck appears to run fine while driving I only noticed it while setting at a stop light idling could the issue be the fuel injectors.
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Saturday, February 27th, 2010 AT 8:25 AM

8 Replies

Tiny
RACEFAN966
  • EXPERT
When you say you replaced the entire ignition system what does that include (please list parts replaced). Have you checked anything else and if so what? Get back to me so I can try to help figure this out.
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Saturday, February 27th, 2010 AT 8:53 AM
Tiny
CARADIODOC
  • EXPERT
Chrysler has very little trouble with injectors. The engine computer should be memorizing a fault code related to a cylinder misfire if that is indeed what is happening. The best approach is to connect the hand-held computer to watch the sensor readings while the engine is idling. In particular, look for an unstable reading from the MAP sensor.

You should also check the engine mounts. If the rubber isolators are missing, or the two parts of the metal brackets are touching, engine vibration will be transfered into the passenger compartment. The clue is the engine will sound normal when you listen under the hood. Metal-to-metal contact of exhaust pipe hangers can do the same thing.

Also look for a sticking-open EGR valve. They only open at higher engine speeds when you won't notice the introduction of exhaust gas into the engine. When it sticks open at idle, the incoming air and fuel is diluted and will cause rough engine operation or stalling. The valve also should never open until the engine is warmed up.

Caradiodoc
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Saturday, February 27th, 2010 AT 8:54 AM
Tiny
MOPAR123
  • MEMBER
I have replaced the cap, roter, pluges wires, and coil. The only thing I did not replace on the ingnition is the distuburter
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Saturday, February 27th, 2010 AT 9:16 AM
Tiny
RACEFAN966
  • EXPERT
What plugs did you use and did this start before the tune up or after? Do you have a digital multi meter? I would like to ohm out a few injectors to rule them out. Get back to me
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Monday, March 1st, 2010 AT 8:48 AM
Tiny
MOPAR123
  • MEMBER
I used the same plugs I have been using for years. This problem started before the tune up and is what prompted the tune up. Yes I do have a digital multu meter
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Monday, March 1st, 2010 AT 10:05 AM
Tiny
RACEFAN966
  • EXPERT
If you would check your injectors first. I need you to unplug them and ohm them. They should be 10-16 ohms. The reason for the question of plugs and such was to get history so I wouldn't make you go through things you already covered. Let me know what you find and we will go from there.
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Tuesday, March 2nd, 2010 AT 9:30 AM
Tiny
MOPAR123
  • MEMBER
Thank you I will test them this weekend when I get back home I will keep you posted
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Tuesday, March 2nd, 2010 AT 10:01 AM
Tiny
RACEFAN966
  • EXPERT
Ok sounds good let me know what you find.
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Wednesday, March 3rd, 2010 AT 9:55 AM

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