[ehinkfus]

Hello, I am having some issues with the trans on upshift, and downshift. It seems like when going up into 3rd gear the trans shifts hard while slowly accelerating? It seems like it jumps up the rpm's all of a sudden? If I accelerate a little more than moderately it doesn't happen? Also when coming to a stop it seems like the trans is not downshifting correctly if I come to an abrupt stop. If very slowly coming to a stop I don't notice it? Kinda hard to explain? I recently added the superchips programmer, and this happens whether running the gas saver mode or 87 octane mode. I have 37's and have used the option in the programmer to let it know I have larger tires. I have been reading threads and have noticed several times people talking about, electrical noise throwing off the torque converter? Im obv. getting pretty confused. Just trying to start eliminating issues..... Any input is appreciated!!!! Thanx E.
08 Ram 5.7 Quad cab 6" lift 20"r 37"t 63K miles

 

[TransEngineer]

Well, I don't have a whole lot of advice for you, but I can tell you:

• There is no way electrical "noise" can affect the torque converter. The converter is completely mechanical; it has no electrical connections or circuits at all. So the idea that an electrical issue could mess up the converter is kind of like wondering whether a flat tire might be caused by low coolant level.
• Your 37" tires WILL change your shift points, even if you've adjusted the pinion factor to account for them. The pinion factor is used to calculate vehicle speed (you adjust the pinion factor to make the speedometer read correctly), but the transmission shift pattern is based on actual output speed (not vehicle speed). Therefore, larger tires will raise the speed (vehicle speed) at which your shifts occur. This should not, however, give you harsh shifts.
• You might try having your dealer run a quicklearn procedure on the trans. They do this using a scan tool (it only takes a few seconds once the scan tool is hooked up). A quicklearn resets the shift adaptives to "factory" settings and re-learns all the clutch volumes. So if something has learned out of whack somehow, a quicklearn can often correct it.

 

[ehinkfus]

Hey, thanx for the input! I think I was mixing up several different theories on what could cause this surging.... After doing a little more searching/troubleshooting. I found the mds was kicking in and out? At low speeds? So I'm not sure if that changes your thinking as far as relearning the shift adaptives. I found out I can shutoff the mds with my programmer. After shutting the mds off, the truck has NO erratic anything. Runs great! So the plan at this time is just to keep it off, but I am thinking the mds should be looked at regardless?

I will get a little worse mpg's but i'd rather have the power!

 

[TransEngineer]

Hey, thanx for the input! I think I was mixing up several different theories on what could cause this surging.... After doing a little more searching/troubleshooting. I found the mds was kicking in and out? At low speeds? So I'm not sure if that changes your thinking as far as relearning the shift adaptives. I found out I can shutoff the mds with my programmer. After shutting the mds off, the truck has NO erratic anything. Runs great! So the plan at this time is just to keep it off, but I am thinking the mds should be looked at regardless?

I will get a little worse mpg's but i'd rather have the power!

Great! So it sounds like the problem was MDS all along (not the trans). I don't know whether anything can be done to "fix" the MDS (sorry, I have no knowledge in that area).