2003 Dodge Caravan 2.4L I4 Stumble at Idle

[Creed]

Hi all,



My 2003 Dodge Caravan 2. 4L I4 stumbles at idle, much more so when the A/C is on and in gear while not moving. It seems to run fine while driving down the road or while accelerating.



New plugs installed about 1000 miles ago. Fuel pressure is good; 66psi at the rail. No trouble codes are set and disconnecting the MAP sensor makes it only a little worse.



Does anyone have any experience, ideas or thoughts/pointers.



Thanks!

 

[PToombs]

Vacuum leak someplace? I don't know how much vacuum stuff is on the newer vehicles. My 95 gasser w/ 318 had a rough idle and a bad stumble when you stepped on it. Acceleration was fine. Had a bad leak someplace. I just plugged that circuit and it runs good now.

 

[BrianJ]

Just today I fixed my wifes '03 Ford Escape (V6) that was having "engine stumble" at idle and take off. Had a check engine light and scanner showed No. 5 cylider missing. Ended up being the coil on #5. I could see where there was some arc'ing on the coil.



Maybe something to look at in your scenario?

 

[Creed]

Thanks guys. Problem still exists and getting worse.

I checked for vacuum leaks and found none. In fact, the engine speeds up and runs smoother when I pull a vacuum line off. I checked the PCV valve (I've never seen one go bad) and it still rattles and breaths. However, while I had the PCV valve out with engine running, there seemed to be a lot of blow-by gases coming out of the PCV outlet. Not sure if that's normal.



I don't see anything really jumping around while monitoring the MAP, Intake Air Temp, Throttle Position, Ignition Advance, Calculated Load and Engine RPM. Not sure what to look for in Short and Long Term Fuel Trim.



I did get some undocumented trouble codes for a brief moment, then they disappeared:

P002C

PB325

P65FF

P4F59



And this one with a description:

TC1 -P0023 b) "B" Camshaft Position - Actuator Circuit Bank 2

Disappeared shortly after it was set.



Here's a full OBDII readout:



MIL is OFF 0 stored Trouble Code(s)

Misfire Monitoring Complete

Fuel Sys. Monitoring Complete

Component Monitoring Complete

Catalyst Monitoring Complete

Evaporative System Monitoring Incomplete

O2 Sensor Monitoring Complete

Fuel Sys1-Closed Loop Mode

# of O2 Sensors -------- 2

OBDII

Calculated Load -------- 9%

Coolant Temp ----------- 192. Deg F

Short Term FT,B1 ------- - 3. 1%

Long Term FT,B1 -------- - 6. 3%

Manifold Absolute Pres. - 16. 2inHg

Engine RPM ------------- 778. 5RPM

Speed ------------------ 0MPH

Ignition Advance ------- 11. 5Deg

Intake Air Temp -------- 127. Deg F

Throttle Position ------ 14. %

O2 Sensor1 Val --------- . 82 Volts

O2 Sensor2 Val --------- 1 Volts

Distance with MIL ----- 0Mi



Installed a new Idle Air Control valve => No change



Tested the ignition system:

Check spark plugs' gaps and conditions => OK

Check spark plug wires' resistances:

#1 > 3kΩ ; #2 < 4kΩ ; #3 < 4kΩ ; #4 = 4kΩ => All seem reasonable

Check ignition coil resistances:

Primary: #1 - #4 = 0. 5Ω ; #2 - #3 = 0. 5Ω => All seem reasonable

Secondary: #1 - #4 = 15kΩ ; #2 - #3 = 15kΩ => All seem reasonable



I will check fuel delivery next.

 

[mdilling]

Did you pull the air intake hose and clean the gunk from around the throttle plate? Prop throttle wide open and clean with a rag and o2 sensor safe carb cleaner or throttle plate cleaner. The more blow by the more often this needs to be cleaned