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Discussion Starter #1 (Edited)
Hi All,

Not sure if this is something normal or a sign of a big issue. Wondering if anyone else has noticed this in their challengers. I have a 2014 RT Classic, 5 speed auto with MDS, and super track pack. I use Valvoline full synthetic with SRT oil filter, and 89 gas. Have a K&N cold air intake and Flowmaster Force II cat-back exhaust. Bought my Challenger 2 years used, have had it a year and a half. Not sure if this has been an issue the whole time, or if it's gotten worse over time, as I usually drive in automatic mode and would not know what gears it is in.

This only happens in a very specific scenario. Using manual sifting mode so I can tell which gear it's in looking at the gear number displayed on the dash. When I was previously in a higher gear such as 4th and decelerate letting it shift itself into the lower gear 3rd. Then when I accelerate the RPM's will rise quickly such as from 1.5k rpm to 2.5k rpm, while still accelerating the rpm will then drop to about 2k rpm and continue to rise slower from there as I accelerate, this all while being in 3rd gear and accelerating continuously.

This happens every time I accelerate in that gear, if I had previously been in a higher gear. If I was previously in 4th and let it shift itself into 3rd from decelerating. Then I can accelerate in 3rd, notice rpm climb high and drop down while continuously accelerating. While still in 3rd I can decelerate again staying in 3rd and accelerate again, and again the RPM will rise then fall a bit while continuously accelerating.

This RPM rising then falling and rising again is noticeable in 2nd gear also, but less noticeable. After having been in 3rd and it having it shift itself into 2nd from decelerating, then me accelerating. It's not as noticeable in 2nd, the rpm will drop only about 0.1k rpm mid-acceleration when it happens in 2nd.

This does not happen if I was previously in a lower gear, such as going up through the gears 1st, 2nd, 3rd, 4th, there is no rpm dropping in any gears in that scenario. Also this does not happen if I downshift it myself, instead of letting it downshift itself by decelerating to very low RPM.

Anyone else experience this? Know what this could be? Any suggestions I can do to fix or ensure it doesn't turn into a big issue? I made an appointment for the dealership to look at it, hopefully they will be able to recreate the issue.

Thanks!
Deonild
 

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I wonder if the torque converter clutch goes into lockup mode - if you're accelerating moderately.

That sounds about what the rpm drop would be with the TCC engaging or dis-engaging
 

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Discussion Starter #4
Thanks for the comments!

Do you think this is expected behavior, programmed to behave this way? Or it is something I should bring it in to the dealer for and possibly need a fix?

Thanks
 

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Discussion Starter #6
Yea the beginning take off in that video is like a more extreme case of it, assuming it's not showing gear change on dash. I haven't floored it in 3rd after it downshifts from 4th to see if it would be that big of a rpm drop within 3rd. That video sounds about 2k rpm drop at least.

Still seeing if any opinions if I should take it in to dealer and agree if they talk about replacing any parts in transmission, or if think it's normal behavior since stock programming?

Thanks

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When you're shifting manually the adaptive shifting algorithm will change the delay in upshifts / downshift and the rate the TCC locks / unlocks

Probably when driving in Automatic mode the clutch converter locks up earlier (it can lock in 3rd gear) and stays locked through 4th > 5th shifts.

if you give more throttle, say while cruising and not enough for a downshift, the TCC will unlock.

I can do this on my Mercedes and it can feel like a shift but its less rpm than what a downshift to a lower gear would be.
 

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Discussion Starter #8
Thanks for the replies all! I think it sounds like normal behavior, after reading more about torque converters. Going to cancel dealership inspection and will just monitor it to make sure doesn't change.

Thx
Deonild

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