GMT 900 Trucks General Discussion 2007 - 2013 Trucks | General Discussion

New problem :( rpm "flutter"

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Old May 8, 2012 | 12:28 PM
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Default New problem :( rpm "flutter"

A little history of events with my truck for those that havent been following. I put in an ls9 cam and the next day I somehow trashed the stock torque converter. Had my tuner just tune it completely out til I could get it replaced and drove around with it permanently unlocked for about 2 weeks. Bought a brand new Circle D converter (multidisk) and had it installed. Went back to my tuner the same day the converter was installed for him to turn the lockup back on and touch up the tune. Now I'm having a new problem.

Since the day the new converter was installed, I'm having an rpm "flutter" at certain situations. The two situations are during idle and while cruising at a constant speed. The rpms will intermittently jump up and down slightly. Like maybe 100-200 rpms. When this happens while cruising, it is subtle enough that you can't really feel it, but you can see the rpm needle move. When stopped at idle, it is just enough change in rpm to feel a small vibration. If you have the hood open, you can also see the motor "vibrate" when the small flutter happens. It doesn't happen when accelerating (either light or heavy). The rpms are smooth and right where they should be.

Neither I or my tuner can figure out what is causing this. does anybody have any insight? Do yall think its engine related? Trans related? I have done all the basic trouble shooting I can think of. Checked the plugs and plug wires, checked hoses for vacuum leaks, checked all wire connections, etc.

I will take a vid to show both situations.

I know this is probably trivial to y'all since there seem to be no negative side effects, but I am paranoid and dont want to hurt anything else if it can be avoided. Thanks.

Last edited by drummer0415; May 8, 2012 at 12:45 PM.
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Old May 8, 2012 | 12:36 PM
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Originally Posted by drummer0415
A little history of events with my truck for those that havent been following. I put in an ls9 cam and the next day I somehow trashed the stock torque converter. Had my tuner just tune it completely out til I could get it replaced and drove around with it permanently unlocked for about 2 weeks. Bought a brand new Circle D converter (multidisk) and had it installed. Went back to my tuner the same day the converter was installed for him to turn the lockup back on and touch up the tune. Now I'm having a new problem.

Since the day the new converter was installed, I'm having an rpm "flutter" at certain situations. The two situations are during idle and while cruising at a constant speed. The rpms will intermittently jump up and down slightly. Like maybe 100-200 rpms. When this happens while cruising, it is subtle enough that you can't really feel it, but you can see the rpm needle move. When stopped at idle, it is just enough change in rpm to feel a small vibration. If you have the hood open, you can also see the motor "vibrate" when the small flutter happens. It doesn't happen when accelerating (either light or heavy). The rpms are smooth and right where they should be.

Neither I or my tuner can figure out what is causing this. does anybody have any insight? Do yall think its engine related? Trans related? I will take a vid to show both situations.

I know this is probably trivial to y'all since there seem to be no negative side effects, but I am paranoid and dont want to hurt anything else if it can be avoided. Thanks.
Damn im sorry to hear about all the problems ur having kinda sucks the big one, how many miles does it have now? but post up some videos
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Old May 8, 2012 | 01:20 PM
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Here is an example cruising at 65mph. I am not modulating the throttle at all. I am holding it steady at a very light throttle to maintain 65mph. In the vid you can see one or two very noticeable jumps in rpm, and many small flutters.

http://i192.photobucket.com/albums/z...5/56f04ece.mp4

Not sure why the sound doesn't work but it doesn't matter cuz you can't hear the changes in rpm anyways.
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Old May 8, 2012 | 01:21 PM
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Not saying anything bad about your tuner here at all, but I might get a second opinion (different tuner) to take a look at it. It always helps to have a second set of eyes on a problem.
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Old May 8, 2012 | 01:31 PM
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I am considering that, thanks. I trust him, but maybe there is something he is missing.

Any other ideas?
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Old May 8, 2012 | 01:37 PM
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what Carbongmc said and after seeing the video i kinda wanna say its the tune since it was on cruise control but i could be wrong
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Old May 8, 2012 | 01:53 PM
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Mine does the same thing. Are you running a VVT cam?
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Old May 8, 2012 | 01:59 PM
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Originally Posted by cam
Mine does the same thing. Are you running a VVT cam?
no. it is an ls9 cam, non VVT. what about you?
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Old May 8, 2012 | 02:26 PM
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talk to justin/blackbear or flaco or any other number of tuners...and stop hammering the throttle all the time, your mpg is suffering!! lol
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Old May 8, 2012 | 02:37 PM
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Originally Posted by LS1Aggie09
talk to justin/blackbear or flaco or any other number of tuners...and stop hammering the throttle all the time, your mpg is suffering!! lol
How bout I hammer your mom instead?
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