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Random misfire between cylinder 2 and 3 on 2006 Rubicon

Robert Alford

New Member
Joined
Mar 29, 2018
Messages
9
Location
Beaumont, TX, USA
Ok gentlemen, Iam back chasing a new issue. This one may stump as I have taken most actions possible, and couldn't find a similar post. If i break any forum rules let me know and it will be fixed.
06 Jeep Wrangler Rubicon with a brand new engine.

Problem:
Random misfire usually between cylinder 2 and 3. I know this because the spark plugs will quickly (30 minutes) foul out. I can attach a video, but when testing the coil pack I noticed that randomly, and I do mean randomly some sparks won't fire at the appropriate time (this is where I think the issue lies). Have noticed the pipes will turn cherry red within 30 minutes, but the thermostat remains normal.

Actions Taken:
First the coil pack is a year old, will pass Ohm test (bought these items chasing a previous issue)
The OPDA is a year old
CPS is a year old
New Injectors, and can hear them firing
Cleaned IAC (was very nice)
Timing is spot on
 

Jerry Bransford

TJ Guru
Supporting Member
Joined
Nov 9, 2015
Messages
12,545
Location
Escondido California
Exactly what brand and model # spark plugs are installed? If they are platinums, are they single or double-tipped? As in is the platinum coating on just one or both sides of the gap? Single-tipped platinums will cause misfires on newer TJs with the ignition coil rail instead of a distributor.
 
OP
R

Robert Alford

New Member
Joined
Mar 29, 2018
Messages
9
Location
Beaumont, TX, USA
UPDATE: A couple weeks ago we replaced the COIL pack again, and that cleared up the misfire (wanted to make sure this was cleared before updating). PSA: The OHM test is not a perfect way to test a coil, as mine passed. We pulled off the rubber pieces and held the coil against a metal rod, to which we could see they did not fire correctly every time.

New Issue: Now the Jeep will randomly die at low RPM after driving around for awhile, like when pressing in the clutch for a slow speed turn or stop light. The idle RPM after warmed up will be around 500, and when the accelerator is pressed the RPM gauge will dip slightly before going up. About a year ago a very similar thing happened and was fixed by replacing the PCM, although this is a new PCM and I would like to think this would not be an issue.
 
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Reactions: Chris

Chris

Administrator
Staff Member
Joined
Sep 28, 2015
Messages
41,877
Location
Salem, Oregon
What brand of coil pack replacement did you use? It's possible that these things are picky about only using OE Mopar coil packs as they are with spark plugs and other sensors.

The other issue you are describing with the idle sure sounds like a dirty IAC / throttle body to me.