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| Timing Rattle with GDE?? http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=49434 |
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| Author: | Tinman [ Tue Jan 19, 2010 4:37 pm ] |
| Post subject: | Timing Rattle with GDE?? |
Since getting the GDE eco tune, I have noticed a strange rattle. This ONLY occurs when the truck is coasting with the TQ unlocked. Mostly this is in first or second gear at slow speed. It doesn't seem to be chassis related. I was wondering if it could be timing rattle from the advanced timing of the tune. I goes away with any load (not moving in gear) or any throttle, or at idle. Timing rattle is a term used on the Cummins forums for a rattley sound that a CR motor makes when timing is advanced beyond a certain point. As the timing advances, the cylinder pressure rises and gets to a point where the pressure spike is audiable and the motor starts to sound like a non-CR motor (the classic loud diesel sound). If that's what it is, I'm not worried, but I am curious. |
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| Author: | GreenDieselEngineering [ Tue Jan 19, 2010 5:31 pm ] |
| Post subject: | Re: Timing Rattle with GDE?? |
Tinman, When you say "coasting" is your foot completely off the accel pedal? If so, then there is no fuel being injected and the noise is from something other than combustion. If you have very light throttle applied, then it could be combustion noise due to having advanced timing. This is more pronounced in the winter months as we add a couple more degrees of timing advance based on ambient temp. The additional timing helps to offset some of the fuel economy loss due to winterized fuel and a cooler running engine. Combustion noise is contingent on the rise rate of the cylinder pressure, not related to the peak firing pressure. At light load the peak cylinder pressure is less than 40-60 bar, while at peak power the cylinder pressure will be in the range of 140-160 bar depending on several environmental factors. We hope this helps. GDE |
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| Author: | stevesmith7 [ Tue Jan 19, 2010 6:02 pm ] |
| Post subject: | Re: Timing Rattle with GDE?? |
I think I may have the same noise. Only noticed post-GDE tune. Light throttle, low speed. |
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| Author: | Tinman [ Wed Jan 20, 2010 9:32 am ] |
| Post subject: | Re: Timing Rattle with GDE?? |
No throttle. Engine idling with the motion of the vehicle spinning the engine at a little more idle rpms. |
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