Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
1 - 4 of 4 Posts

·
Registered
‘04 Chevy Silverado 2500HD 6.6L LB7 Duramax
Joined
·
4 Posts
Discussion Starter · #1 ·
To make a long story short, I have noticed a lack of power along with lots of smoke upon acceleration in my LB7. I have checked the balance rates along with the fuel rate, but I’ve read different articles saying different things. I would just like to be sure as I need this truck for work and want to be positive before sinking the money on some new SAC style injectors. I do also have some concerns about the FICM since the rubber plug in the side of it is missing. There has been two instances where my truck has spit and sputtered after washing, and then seemed to clear up after a day or two. Thoughts on how I could troubleshoot that? I haven’t been able to find any info on diagnosing the FICM.

The balance rates are as follows:

Engine at operating temp, in park, idling, all accessories off.

Cyl 1: (-0.0)
Cyl 1: (-0.0)
Cyl 2: (-0.3)
Cyl 3: (-0.0)
Cyl 4: (0.1)
Cyl 5: (1.4)
Cyl 6: (-0.4)
Cyl 7: (0.1)
Cyl 8: (-0.4)
Fuel Rate: 10mm3

RPM: 680
DES FRP: 34 MPA
ACT FRP: 34 MPA
 

·
Registered
Joined
·
4,130 Posts
Balance rates look good, better than my truck.
Go to a parts store like O'Reillys and get your truck scanned. The codes give you a hint at where the truck thinks the problem is located.
 
  • Like
Reactions: David Love

·
Registered
Joined
·
292 Posts
Are you able to check your desired and actual rail pressure under acceleration? If my google translator is right, 34 mpa is just shy of 5k psi which is fine at idle but you should be near 23k in a hard pull or at wide open acceleration. You may also test by unplugging your FPR and see what your actual goes to. It should hit 23k even at idle like that and shake something fierce.

My truck did this too and I could see the desired climb along with the actual until around 16-17k and then the actual would drop back to around 5k and it would smoke and do lots of weird stuff. I also couldn't get 23k at idle with the FPR unplugged without running up the rpm. I had to replace the cp3 but my truck had 270k on it.

If your actual and desired match and it can hit 23k I would look toward it being an air problem then. Ron is right with your balance rates being good and if the pressure is good I would suspect a boost leak or maybe a plugged air filter.
 
  • Like
Reactions: David Love

·
Registered
‘04 Chevy Silverado 2500HD 6.6L LB7 Duramax
Joined
·
4 Posts
Discussion Starter · #4 ·
Are you able to check your desired and actual rail pressure under acceleration? If my google translator is right, 34 mpa is just shy of 5k psi which is fine at idle but you should be near 23k in a hard pull or at wide open acceleration. You may also test by unplugging your FPR and see what your actual goes to. It should hit 23k even at idle like that and shake something fierce.

My truck did this too and I could see the desired climb along with the actual until around 16-17k and then the actual would drop back to around 5k and it would smoke and do lots of weird stuff. I also couldn't get 23k at idle with the FPR unplugged without running up the rpm. I had to replace the cp3 but my truck had 270k on it.

If your actual and desired match and it can hit 23k I would look toward it being an air problem then. Ron is right with your balance rates being good and if the pressure is good I would suspect a boost leak or maybe a plugged air filter.
Balance rates look good, better than my truck.
Go to a parts store like O'Reillys and get your truck scanned. The codes give you a hint at where the truck thinks the problem is located.
I have a Snap On Solus scanner, so I am able to look at whatever/whenever on the truck. That being said, the only code I have stored in the history is a glow plug controller code. The security light is steady on in the truck, but it has been like that since I got it 2 years ago. I do know that my turbo is on its last leg, but I wouldn't think that would cause the slight rough idle?
 
1 - 4 of 4 Posts
Top