Help with rough running

M

megastang

New member
Here's the story. My wife started complaining about rough running in her 06 a while back. I scanned it with efi live and saw rail pressure was way high. replaced fca solved the rail pressure problem but the rough running was still there. checked balance rates and cylinder 4 was at 4mm. Initial fire up after injector replacement was very rough with lots of white smoke even after a couple minutes. Went for a drive and things seemed to smooth out but balance rate is still at 4.

what are the chances that a bad injector took out the #4 cylinder? I know on 3412 cats if you don't catch a bad injector you can take out a cylinder pretty quick. are these motors the same way?
 
These motors hide a bad injector well! Not until it's way past saving do signs show up! Pull the injector and have a look inside!
 
I finally did a compression test and it came in right around 500psi. Now i'm really lost. I had checked the cylinder wall with a borescope and could see cross hatch all the way around. I am going to try swapping the new injector to another cylinder and see what happens. Any chance that a burnt valve could be causing these symptoms but still pass a compression test?
 
alldata says minimum 350 psi. I did not put in a new crossover tube I figured I would take my chances. I switched #4 (the reman) to #1 and checked balance rates. #4 was previously at 4mm. now #4 is at 3.9 but #1 is at -2.2 and #6 is at -1.8. As far as I can tell it's not the injector or the rings but i'm not sure what else could be the cause.
 
i'm just about to the end of my rope with this thing. Last night I put some injector cleaner in the tank and took it out for about a 30 minute drive. When I first started the truck terrible white smoke and rough idle just like it has been doing since the injector issues. After the drive the smoke is gone and if there is a miss it is so minor that I can't tell if there really is a miss. :doh:
 
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