[neuroticdave]

So I finally got around to disconnecting my car battery and resetting the cars parameters. Once plugged in, I took it out for a "lively" drive on the highway. I used Autostick to give her some healthy WOT runs, but at one point I left it in D @ 65MPH and just mashed it.

Well, the ultimate result was not very nice. It THUNKED it's way down to 3rd gear. I then decided to use Autostick again and left it in 4th and decided to downshift and once again, THUNK.

I tried another WOT run from D and same result, a rough THUNK down to 3rd. At another instance I used Autostick to get into 3rd and gave it some light to mild mashes of the gas, and it was quite rough.

Is there something I should look into in specific to fix this? Or was the battery pull the possible culprit, and the car just has to learn it's way around? I just bought the car a week ago, but this is the first time I've opened her up like that.

 

[EddieFL]

What type of Charger do you have? A 5-speed or 8-speed? If it is the 5-speed, these are NOT known for being smooth, especially during aggressive driving. I have owned three cars with this transmission including my Charger and they can make thunking sounds when shifting hard, mostly when the car has to abruptly downshift under hard acceleration. If you don't notice anything weird when driving under light load this might just be the transmission doing it's thing. One thing I have noticed that makes that worse is when you do WOT then back off suddenly, the transmission is pretty rough in settling back down, like say when you think there might be a gap in traffic and get to speed but have to back off because you don't think you'll make it. It can trip up the transmission. If you are concerned you might want to take it to the dealership or the next time service is due you can ask to have them check it out.

Edit: Just saw your other post. Well like I said the 5-speed is not the smoothest when downshifting, it can actually be pretty brutal, but you have a car that's been around for a little while so I would try and have someone familiar with the 5-speed ride with you to replicate the issue to see if they think it's normal or something you should look at, if that's a possibility.

 

[RT_HEMICHARGED]

While it is a very solid, strong piece of machinery, the NAG1 tranny doesn't exactly please the driver's senses. I'm sure you're just hearing normal operating noises of this rough old 5 speed.

 

[neuroticdave]

The transmission runs fine during normal operation from what I can see. Only reason I'm concerned is that having owned an 06 Daytona and an 07 R/T in the past, I can't recall it being such a harsh downshift for a WOT run. It had that sudden stop and then surge of power, but never a thunk from what I can remember. It literally felt like someone hit me from the rear. My other concern is that the reason why I sold my C Class Mercedes (722.6 trans) was because of a bad transmission/differential, so maybe it's a mixture of OCD and bad memories. However, there's no CEL, no other red flags that I can think of.

Would a PCM update of some sort help? I'm not sure how much a software update could assist, but worth a shot. Cars under warranty for 2 years.

Is the fluid level as sensitive as it is in the Benz applications of this transmission? I know the electrical connector (which has happened on the Benz cars since 2001, you'd figure by 2008 they'd fix it already) can leak, but not sure how sensitive this version of that trans is to that.

 

[Ddaddy]

Yes, check the fluid level in the tranny. It's the same NAG1 (WA580) that Mercedes used.

 

[richd]

So I finally got around to disconnecting my car battery and resetting the cars parameters. Once plugged in, I took it out for a "lively" drive on the highway. I used Autostick to give her some healthy WOT runs, but at one point I left it in D @ 65MPH and just mashed it.

Well, the ultimate result was not very nice. It THUNKED it's way down to 3rd gear. I then decided to use Autostick again and left it in 4th and decided to downshift and once again, THUNK.

I tried another WOT run from D and same result, a rough THUNK down to 3rd. At another instance I used Autostick to get into 3rd and gave it some light to mild mashes of the gas, and it was quite rough.

Is there something I should look into in specific to fix this? Or was the battery pull the possible culprit, and the car just has to learn it's way around? I just bought the car a week ago, but this is the first time I've opened her up like that.

I thing I noticed is that you dont mention any city driving,thats what your missing.I use 2 do relearn on older Chrysler trannys,and I would take them in the city,start from a stop,then start in 1st and shift it easy into every gear.Do this several times.Let it downshift by itself.Do this several times.Then go on highway,start with lower speed like 50,drive it for a mile,then nail it,go back to normal driving,take it up to higher speed,55/60 drive a mile nail it drive normal,then see if that helps.It might take some miles 4 tanny 2 relearn your driving habits

 

[rob-2]

Not sure you have a real problem. It's the learning process.

Also notice in my 14 that WOT causes very sporty shifts. Nearly bangs through the gears.

 

[djalbin]

I'm not familiar with all the MY's for the Charger R/T but I know with the later models there is some communication between the PCM (5.7L engine) and the TCM (NAG1 transmission).


The PCM controls the engine in closed-loop mode when not WOT (i.e. PCM uses the input from various sensors to control the engine ... and is also communicating with the TCM).


The PCM controls the engine in open-loop mode when WOT. (i.e. PCM is not using any input from the various sensors and is just controlling the engine using the WOT mapping ... and I assume is not communicating with the TCM).


So what's my point ...
Closed-loop mode is going to produce smoother transitions between the engine and transmission (PCM and TCM are working in unison).


Open-loop mode is going to produce rougher transitions between the engine and transmission (PCM and TCM are working independently).


Quick transitions back-n-forth between closed-loop and open-loop modes is going to produce rough transitions (PCM and TCM are thrashing until they are in a steady state again). The behavior of the transmission when going WOT will depend on the speed/gear the car was in when going from closed-loop to open-loop.


So as some of the other posts suggest ... your car may be performing as expected.

 

[neuroticdave]

Thanks for all the replies guys, I think I'm going to do drive her mildly around the city and on the highway for a few days before I try another WOT run. I was thinking that maybe since I reset everything, that sudden WOT run might have confused the car. Outside of that, transmission shifts fine, but if I note it again at a latter time, I think I might have the dealer check fluid level and the connector plug, to ensure there's no leaks.

Is there a specific method to ensuring the car relearns its shift points properly? I know in the 722.6 application of this transmission, there is a set method that involved riding it on gear X up to X RPMs then slowing down, then riding the following gear up to X RPMs and slowing down, etc etc.

Again, thanks for the help guys!

 

[rob-2]

Don't overthink it. The transmission learned how to shift just fine before you got all worked up about it.