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brownjeff
brownjeff, ASE Certified Technician
Category: Dodge
Satisfied Customers: 13886
Experience:  17 years experience, ASE certified, dealership certified, Service Manager for 15 years,
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I have a 2002 dodge dakota 3.9 litre with a rough idle no codes

Customer Question

I have a 2002 dodge dakota 3.9 litre with a rough idle no codes complete tune up including wires even changed the fuel pump to no avail
Submitted: 7 years ago.
Category: Dodge
Expert:  brownjeff replied 7 years ago.
Is it only rough at idle? It runs good other wise?
Customer: replied 7 years ago.
it does have a slight hesitation
Expert:  brownjeff replied 7 years ago.
From what your describing I suggest cleaning the throttle body with carb cleaner. Also removing the idle air control motor out of the throttle body and cleaning the idle control motor and the passage way it goes in. Then clean the injectors. You have carbon building up and this will take care of the carbon.
Customer: replied 7 years ago.
We have already cleand out the throttle body the scanner picks up no codes or misfires says everything is perfect rough idle and hesitation still
Customer: replied 7 years ago.
what else we have already done that
Expert:  brownjeff replied 7 years ago.
Then the next thing I suggest is running top engine cleaner through the engine to remove the carbon from the valves. The valves will stick when they get a build up of carbon on them and cause the engine to run rough and feel almost like a miss.
Customer: replied 7 years ago.
but it has a hesitation also like a bad TPS but the readings are good on it? so it is not only a rough idle we did change the fuel pump because it had 110 lbs of pressure at idle and when you shut it off it bled to zero in about 2 seconds the new one has 48-50 lbs and does not bleed down
Expert:  brownjeff replied 7 years ago.
It still could be an issue with carbon. Also I suggest taking a compression reading to make sure the engine is mechanically good.
Customer: replied 7 years ago.
compression done both wet and dry perfect across the board
Expert:  brownjeff replied 7 years ago.
Have you cleaned the injectors?
Customer: replied 7 years ago.
In what way do you suggest the motor does have a noticeable hesitation
Expert:  brownjeff replied 7 years ago.
The best way to clean the injectors is to disable the fuel pump and hook the cleaner up to the fuel rail and run the engine off the cleaner.
Customer: replied 7 years ago.
do you think that the injectors would cause a very noticeable hesitation
Expert:  brownjeff replied 7 years ago.
Yes they can certainly cause a noticeable hesitation.