Ok, sorry it’s been a minute since I’ve posted. I finally was able to access my GM website and check out the relearn procedure. I printed it out and I will try to perform it tomorrow after work. It is a throttle/idle relearn procedure. I thought I did it last week but from what I have read, I need to perform a few more steps. I’ll let you know how it turns out. Thanks again!

 

CRANK is done with scan tool.

 

Sorry, it’s been a while since I was here. On my 06 Vue with the 3.5, I have made the misfire problem go away. For a little history, I’ve been in the repair business for over 35 years. Work on everything but planes, trains and helicopters. This is one I have never seen and makes no sense. I have replaced the fuel pump, tested the MAP sensor function, replaced the CRK sensor and performed the relearn process per GM’s website. Hooked up a scope on 4 coils and checked patterns up to 3000rpm. Everything I can think of with fuel and ignition. This thing came with a K&N cold air intake and the filter was choked up. Cleaned the filter also. Every time I tried something, I would test drive and still had misfire counts on all cylinders. I was about to give up but I decided to rotate the tires due to a vibration on the right front. After rotating the tires, my misfire problem went away. I have driven the car about 400 miles after the rotation and still have a vibration but in the rear. I’m going to replace the tires soon anyway. My thing is, how can a tire vibration cause the CRK sensor pick it up as misfires. This is with the old and new sensor. Makes no sense to me but that’s what fixed this car. If anyone has any insight into this, I would appreciate it. Thanks all!

 

07 Vue v6 J35 engine
Serendipitous timing and curious that I found your post, while searching for the same problem! Getting flashing CEL for a few seconds, at around 75mph, codes show as pending but do not record (not showing on subsequent start). Shows misfire on all cylinders when it occurs though there is no such problem at similar rpms in other gears (and no wheel vibration is present).
(P0300 P0301 through P0306 as pending codes)
Also worth noting, there does not appear to any misfiring taking place that I can tell.
What struck me was that I was getting noticeable front wheel vibration - only at that speed (75mph). So I've been wondering if the misfire detection was caused by the wheel vibration.
I don't know about the J35 engine but on the BMW straight six I have there are 2 sensors on the side of the engine that detect misfires through vibration I believe.
I was thinking about rotating the wheels front to back as the front are a little unevenly worn on the outside (just replaced the front struts and had it aligned) which is what I think is causing the vibration.
Could do with 2 new tires and balancing but will see if the rotation makes a difference first.
Can't seem to find much about misfire detection on this engine other than "crank and other sensors", so maybe someone knows whether the knock sensor plays a part.

 

Could it be very very light vibration that is at just the right frequency being transferred through the knock sensor?
Might not set a knock sensor code because there is nothing wrong with the sensor. However, with the information passed on to the PCM, who knows what's done with it. While somebody does but it's not me. Putting premium in the tank won't help if it's not a real knock.

Put a huge mass on top of the engine, secure it down, and go for a drive. If it doesn't misfire, then the signal is sneaking its way in through the vibration of the block. But if you lower the residence frequency of the block plus Mass, that just may not happen.

All of this is subject to testing and laughter