Something outa balance

[5LTREATR]

so when my truck is in park and i ev the engine up to about 1500 it seems like something is outa balance im not sure how else to explaine it. I had some one else step on the fuel and i watched the engine and it seems to run perfectly. What could the issue be?

 

[gmduramax]

Smoke out the exhaust?

 

[5LTREATR]

there is a little smoke but nothing major sometimes it will and sometimes it wont in hot humid weather it smokes alot more.

 

[MMLMM]

How big of a tune are you running? How fast have you spun the Engine?

 

[5LTREATR]

about 450 rwhp and have never went over 105 miles an hour and 3250 rpms i was wondering if the torque converter cold be a little messed up because i still am running the stock trans and converter.

 

[LBZ]

Your balancer could be loose or hooped.

 

[5LTREATR]

how does that happen and would the engine still visibly look like it is running smooth and wouldnt there be a check engine light?

 

[LBZrcks]

Flex Plate maybe?

 

[moore428]

Rev the motor up slowly, if it is smooth until you hit a certain rpm, then smooths out again at a higher rpm, it's the torque converter.

 

[jneal]

My truck does the exact same thing at the same RPM, 1500. I have seen a couple of other trucks do the same. All of them being LBZ's. I personally think it is nothing to worry about and has nothing to do with hard parts. My engine done it before the build and after the build. Rotating assembly balanced, SOCAL dampner, suncoast converter and still no difference. I think it might have something to do with the base programming, since I 100% believe that it's not a hard part issue.

Just curious is your operationg system 12606128 ?

 

[jneal]

Rev the motor up slowly, if it is smooth until you hit a certain rpm, then smooths out again at a higher rpm, it's the torque converter.

Please explaing this theory. I've seen injector failures do the exact same thing, among numerous other things cause a specific RPM vibration.

 

[LBZ]

Please explaing this theory. I've seen injector failures do the exact same thing, among numerous other things cause a specific RPM vibration.

X2.

 

[x MadMAX DIESEL]

I have same thing come and go... The truck also vibrated in high gear when I was cruising... Dropping a gear killed the vibration... My engine never shook either at that rpm in park but I could feel something vibrating aswell. Never did find anything but I think It was something in the trans... Maybe a loose mount for it??

 

[x MadMAX DIESEL]

Heres a link to my thread.. Nothing real technical but just kind of a releif that nothing has broken in 2 months since the vibration

http://www.duramaxdiesels.com/forum/showthread.php?t=18035

 

[moore428]

If you have a bad torque converter, the first sign is a vibration at approx. cruising rpm. In gear and out of gear. It will seem like a driveline or tire vibration, not a horrible shake or rattle.

 

[Dazedandconfused]

My LLY does it also but its only in a 200RPM band from 1300-1500 RPMs. I just wrote it off due to miles on my engine.

 

[EDP]

Check your damper. It will take the removal of the crank bolt and a flash light and a mirror look into where the crank pin is located. If it comes and goes good possibility when shutting the truck down the damper is spinning ever so slightly and throwing the bottom end out of balance. after a few cycles it can find its home again and balance itself back out. For whatever reason we are beginning to see this on trucks that do a a lot of start up and shutdown through the days time. Not sure if the used a softer pin somewhere in production but we are seeing it become more and more frequenlty.