LOST JEEPS :: View topic - CRD started doing something different when coasting...

If you want to try something really wild pop the gearshift into 2nd when you are coasting at about 40MPH. I treid this the other day when approaching some construction and wanted to see what a little engine breaking would do. For me it seems to cause a mixture of tranny shudder, RPMs varying, and finally a very lethargic geardown into 2nd. Maybe the TCM has a tough time deciding what 2nd gear to pick? Curious how other CRD's behave. Seems to me gearing down at 40 should be perfectly safe, your not anywhere close to overspeeding the engine and might be something you would want to do on a grade to get a little bit of engine breaking. Has anyone else tried this? If so any similar experiences?

Author:	KenJennings [ Tue Oct 10, 2006 9:30 pm ]
Post subject:	CRD started doing something different when coasting...
Around here we have very long off ramps from the highway to the streets, so I had always been coasting off the highway. Just take the foot off the pedal at 70mph and by the time it reaches the street the vehicle had slowed without brakes to about 35. Previously, the RPMs stayed high until the vehicle reached about 55mph and then it would "let loose" -- the RPMs would drop smoothly to about 1000 and a drop in resistance (braking from tranny/engine) is felt as the vehicle coasts unimpeded. Within the last couple days I noticed something different. After it lets itself loose, the RPMs would drop to about 800, and then bounce back up to about 1300. An increase in resistance (braking by tranny/engine) is also felt when the RPMs jump up. A few seconds later -- at about 40mph, it lets loose again like it should and stays that way. I checked the tranny fluid (in Park) and it is right at the high line. I've also noticed the jeep is making a slight "thump" when it begins accelerating from a stop. So, is this the tranny or the torque converter on its way out?

Author:	Endurance [ Tue Oct 10, 2006 9:47 pm ]
Post subject:
I think so. Mine used to do that too, I am now getting a new TC and pump. What might help is the TCM and ECM flash TSB. I think that cured some of these problems. It shifts much smoother, thats for sure.

Author:	Inet_CRD [ Tue Oct 10, 2006 9:59 pm ]
Post subject:
If you want to try something really wild pop the gearshift into 2nd when you are coasting at about 40MPH. I treid this the other day when approaching some construction and wanted to see what a little engine breaking would do. For me it seems to cause a mixture of tranny shudder, RPMs varying, and finally a very lethargic geardown into 2nd. Maybe the TCM has a tough time deciding what 2nd gear to pick? Curious how other CRD's behave. Seems to me gearing down at 40 should be perfectly safe, your not anywhere close to overspeeding the engine and might be something you would want to do on a grade to get a little bit of engine breaking. Has anyone else tried this? If so any similar experiences?

Author:	KenJennings [ Thu Oct 12, 2006 2:16 am ]
Post subject:
Inet_CRD wrote: If you want to try something really wild pop the gearshift into 2nd when you are coasting at about 40MPH. I treid this the other day when approaching some construction and wanted to see what a little engine breaking would do. For me it seems to cause a mixture of tranny shudder, RPMs varying, and finally a very lethargic geardown into 2nd. Maybe the TCM has a tough time deciding what 2nd gear to pick? Curious how other CRD's behave. Seems to me gearing down at 40 should be perfectly safe, your not anywhere close to overspeeding the engine and might be something you would want to do on a grade to get a little bit of engine breaking. Has anyone else tried this? If so any similar experiences? 40?! I did it at 35 and that was downright frightening. Stupid, electronic controlled flibbitty floo. Why the !@#($!#@$ can't we have a manual transmission on the U.S. CRD?

Author:	KenJennings [ Thu Oct 12, 2006 2:21 am ]
Post subject:
Endurance wrote: I think so. Mine used to do that too, I am now getting a new TC and pump. What might help is the TCM and ECM flash TSB. I think that cured some of these problems. It shifts much smoother, thats for sure. Those flash "upgrades" had already been done a while ago. This is new behavior that's just started. I've driven a lot of vehicles, but this Jeep is the first one that acts like it has moods.

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Author:	aardvark4x4 [ Thu Oct 12, 2006 4:07 am ]
Post subject:
Do you not have manual transmission available on your CRDs then? Uk ones are available with the new 6 speed Mercedes transmission found in late TJs. We also had the earlier 2.5 CRD with the NV3500 5 speed.

Author:	Jeger [ Thu Oct 12, 2006 5:35 am ]
Post subject:
aardvark4x4 wrote: Do you not have manual transmission available on your CRDs then? Uk ones are available with the new 6 speed Mercedes transmission found in late TJs. We also had the earlier 2.5 CRD with the NV3500 5 speed. We know you get the 6 speed, dont rub it in What year TJ's was it used in, and was it a diesel TJ or petrol.

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