Runs rough

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I noted you are a mechanic. Have you checked fuel pressure? Also, take a live data scanner and watch the rpm signal to see if it consistent. You may have a bad crank sensor or even cam sensor.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

Also, what are the fuel trims reading both long and short term? Have you checked for a vacuum leak?

Let me know.

Joe

Welcome back:

Fuel pressure should tell the story.

Welcome back:

Do you have a live data scanner? If so, I wonder why you can't see the readings. Let me know what you find with the pressure.

Take care,
Joe

Welcome back:

Your scanner should be able to show fuel trims. Can you tell me what they are, both the short term and long term trims?

As far as the fuel pressure, it's your call. It may have nothing to do with the problem, but it could at the same time.

Let me know.

Joe

Welcome back:

Believe it or not, that is helpful. If you note, the stft are different for each bank of the engine. When you have a negative trim like you do on bank 1, that indicates the computer is trying to lean the bank by reducing fuel. Bank 2 is the opposite, it is trying to add fuel. So what does this all mean?

Negative fuel trim corrections can be the result of maf sensor issues, high fuel pressure, faulty evap components, an oxygen sensor issue, exhaust leaks before the o2 sensors, a problem with the engine coolant temp sensor and so on. It can even be related to engine timing. But, there is another side we have to look at before we start checking.

If the engine is running too lean, you will see a positive fuel trim which can be caused by MAF and O2 sensor faults, vacuum leaks from intake gaskets/hoses, unmetered air entering the combustion chamber. A dirty fuel injector, or an exhaust restrictions, such as a bad catalytic converter (partially plugged).

In a perfect world, you want the trims to be as close to 0 as possible. Since the banks are opposite, then I suspect either you have an exhaust leak on bank 2, an issue with one of the o2 sensors, or the catalytic converter. I say this because of if it was a vacuum leak before the exhaust (bank 2 exhaust manifold) or one of the components I mentioned, the computer would show very similar readings on both banks. Additionally, there could be a leaky injector on bank 1 throwing things off. We can narrow down that certain components will cause bad readings to be the same on both banks

Is there any exhaust leak you hear when the vehicle is first started? Most times, a small exhaust manifold leak is most noticeable when the engine is started cold and sounds like a tick. Also, is there any odd smell from the exhaust that could indicate an issue with the catalytic converter associated with bank 2? Have you ever tried cleaning the fuel injectors?

Just fyi, when checking fuel trims, you should check in neutral at idle and at 2500 rpm's. I don't know how close you were to that.

Let me know if that helps and if you ever noticed an exhaust leak.

Joe

Welcome back:

Have you checked fuel pressure yet? At this point, I wonder if there is a leaking injector. You need to check pressure and leak down.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the specs:

2002 Kia Truck Sedona EX V6-3.5L
Pressure, Vacuum and Temperature
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Specifications Pressure, Vacuum and Temperature
PRESSURE, VACUUM AND TEMPERATURE
Fuel Pressure Specifications

Idle vacuum connected .................... 39 PSI

Idle vacuum disconnected .................... 46-49 PSI

Hold pressure .................... No specification provided by manufacturer

If you haven't, this needs done.

Joe

Fuel pressure is perfect. When you first started working on this, there was a misfire on cylinder 2. You replaced plugs and wires and all was good for a very short trip. Is it acting the same as it did before you replaced the plugs and wires? Have you pulled cyl 2 plug to see if it indicates any issues?

At this point, if there are no vacuum leaks, the fuel pressure is good, and it is holding pressure (which tells me there are no injectors leaking), then we may have a compression issue or a timing issue. You have checked about everything that is common to cause it to run rough with nothing showing bad. I guess it is time to do a compression test to see if there is a low cylinder (#2 Possible). Honestly, if the compression is within spec, then the timing is most likely not the issue.

You have checked to confirm there are no plugs or wires arcing, correct?

https://www.2carpros.com/articles/how-to-test-engine-compression

Here are the directions specific to your vehicle. The attached picture correlates with the directions.

____________________________

2002 Kia Truck Sedona EX V6-3.5L
Component Tests and General Diagnostics
Vehicle Powertrain Management Tune-up and Engine Performance Checks Compression Check Testing and Inspection Component Tests and General Diagnostics
COMPONENT TESTS AND GENERAL DIAGNOSTICS
Checking compression pressure
1. Before checking compression, check the engine oil level and that the starter motor and battery are all in normal operating condition.
2. Start the engine and wait until engine coolant temperature has risen to 80 - 95°C.
3. Stop the engine and disconnect the spark plug cables.
4. Remove the spark plugs.
5. Turn over the engine to remove any foreign objects in the cylinders.
6. Attach the compression gauge to the spark plug hole.
7. Depress the accelerator pedal to fully open the throttle valve.

pic 1

8. Turn over the engine and read the gauge.
Standard value: 1,200 kPa (12.2 kg/cm2, 170 psi)
Limit: 1,050 kPa (10.7 kg/cm2, 149 psi)
9. Repeat steps 6 through 8 on all cylinders, making sure ensuring that the pressure difference for each of the cylinders is within the specified limit.
Limit: Max 100 kPa (11.0 kg/cm2, 14 psi) for all cylinders.
10. If a cylinder's compression or pressure difference is below the specification, add a small amount of oil through the spark plug hole and repeat steps 6 through 9.
1) If the addition of oil causes the compression to rise, it is possible that there is wear between the piston ring and cylinder wall.
2) If the compression doesn't rise, valve seizure, poor valve seating or a compression leak from the cylinder head gasket are all possible causes.
Tightening torque Spark plug: 20 - 30 Nm (200 - 300 kg.cm, 14.75 - 22.13 ft. lbs.)

____________________________
Other than that, there was a technical service bulletin regarding a rough idle. It required the throttle body to be cleaned.
https://www.2carpros.com/articles/throttle-actuator-service

Here are the specific directions from the TSB.

2002 Kia Truck Sedona EX V6-3.5L
Fuel System - Throttle Body Cleaning Procedure
Vehicle Powertrain Management Technical Service Bulletins Fuel System - Throttle Body Cleaning Procedure
FUEL SYSTEM - THROTTLE BODY CLEANING PROCEDURE
VOLUME
3

GROUP
Fuel

NUMBER
010

MODEL
All

DATE
September 2005

SUBJECT:
THROTTLE BODY CLEANING

This bulletin provides information relating to throttle body and plate cleaning on all Kia models. Residue from fuel additives and/or carbon deposits that result from normal fuel combustion can accumulate on the throttle body and/or upper combustion chamber over time. Dirty throttle bodies can cause a variety of vehicle drivability concerns and may result in MIL illumination under certain circumstances.

When the engine is started, the incoming air sometimes carries residue back to the throttle body and deposits it just behind the throttle plate because of the sudden drop in air pressure behind the plate.

pic 2

When the engine is running, crankcase vapors enter through the PCV system and work their way into the intake system. These vapors carry with them residue which accumulates on the idle passages and throttle plate. This build-up eventually blocks the air gap between the throttle plate and throttle body bore, causing less airflow while the throttle plate is closed. Over time, the computer compensates for the reduced airflow with fuel trim adaptive logic adjustments, as it becomes more difficult for the computer to control the idle, especially when coming to a stop or when the throttle is "snapped". Do NOT replace the throttle body before the throttle plates are cleaned for any condition related to fuel trim values.

THROTTLE BODY CLEANING PROCEDURE:

pic 3

1. Remove the intake duct hose that is connected to the throttle body.

WARNING
Make sure the application straw is securely attached to the throttle plate cleaner nozzle. Failure to do so may result in a straw that has come off and is now stuck in the intake manifold assembly.

pic 4

2. Using throttle plate or equivalent cleaner, open the throttle to the Wide-Open-Throttle (WOT) position. Clean out the throttle body bore and throttle plate using a small soft metallic (brass) or stiff bristled brush as necessary.

3. After the cleaning is complete, reinstall air intake duct hose. Be sure all throttle cables are routed correctly then, start the engine. The engine will run rough until all the throttle plate cleaner is burned off from the internal vacuum circuits. Shut engine off.

4. Remove the ECM memory fuse for 10 seconds and then re-install. This will reset the fuel trim adaptive values. Not all models use the scan tool to clear the adaptive fuel trim values.

Note:
Removing the ECU memory fuse will not affect the loss of voltage to other control modules requiring the windows to be initialized, ETS, sunroof, overhead displays, radio station presets.

pic 5

ECM Memory fuses are as follows:

5. Road test the vehicle approximately 2-3 miles before returning the vehicle to the customer.

pic 6

PART NUMBER INFORMATION:

Note:
The Throttle Plate Cleaner and other chemicals are NOT available on Kia's DCS system and must be ordered through Kia's Chemical

Let me know what you find.

Joe

Welcome back:

You are very welcome. I hope something I mentioned help you out.

Take care and let me know what you find.

Joe