[Dudeman]

I have a potential concern with my 5-speed transmission in my 2013 300c.

It shifts rough compared to the other examples of the same car that I have driven and it seems like it holds gears too long before it will downshift.

When I remove my foot from the accelerator, the car slows down rather quickly and doesn't coast smoothly. It acts like it not in the appropriate gear for the vehicles speed.

When it does downshift, the engine revs and growls and the RPM's spike harshly.

Now, I stopped by the dealer service center yesterday and the guy I asked about it said it was "completely normal" and a "cool feature of the vehicle". He explained that the car is shutting off the fuel injectors and using the weight and momentum of the vehicle to slow it down.

He never looked at the car, drove it or asked any questions about the circumstances of my concerns. It took him about thirteen seconds to determine that there was nothing wrong with my car.

I have read about others that have had rough shifting from the 5-speed transmission and it seems like resetting the shift points and re-flashing the control unit has solved their problems.

Should I take my car to a different servicer?

Also, I have owned the car for about six weeks and it has about 20,000 miles on the clock. I assume that should be ample time for the computer to learn my driving habits.

Thoughts?

 

[MADDOG]

That does not sound normal. I'd find a different dealer.

 

[thrifty]

Damn!!! Six weeks and already at 20,000 miles... Hope you bought the lifetime warranty!!!

 

[Dudeman]

All of the miles aren't mine! LOL. Only about 800 belong to me.

I went back to the dealership and spoke with someone else. They are going to set me up with an appointment to do proper diagnostics. Hopefully nothing too major.

We'll see in a few days.......

In the meantime, does anyone else feel like there is something actively slowing their car down while coasting? The other examples of the car that I test drove didn't do that and the rental car that I had didn't either. All were 2013 models with the 5.7 and 5-speed transmission.

 

[DESIREE]

All of the miles aren't mine! LOL. Only about 800 belong to me.

I went back to the dealership and spoke with someone else. They are going to set me up with an appointment to do proper diagnostics. Hopefully nothing too major.

We'll see in a few days.......

In the meantime, does anyone else feel like there is something actively slowing their car down while coasting? The other examples of the car that I test drove didn't do that and the rental car that I had didn't either. All were 2013 models with the 5.7 and 5-speed transmission.

They will do it if you are going down a long hill and are on the brakes for a length of time.

 

[tanbam]

Of you have cruise control on and are going down a hill, the engine will downshift and use engine braking if you go to far over the set point.

If you have adaptive cruise, it will apply the brakes to keep the speed constant.

 

[Dudeman]

I had thought about those things. Here in Florida, we don't really have much in the way of long downhills and I seldom use the cruise unless I'm on the interstate or turnpike. No ACC on my 300C either.

The times I notice it the most are in between red lights, (roughly every 1/2 mile on main roads here) or when I'm cruising around at highway speeds and release the throttle to compensate for upcoming traffic. Once I release the gas pedal, the car starts to dramatically slow down and the engine and transmission act like I described above.

It just doesn't seem right to me and is definitely not a "cool feature of the vehicle".

 

[tanbam]

No, there's something wrong then. It should just coast along.

Try shifting into neutral the next time that it happens and to see if something (like a sticky brake) might be a factor.

 

[jeyaar789]

Does your car have the steering wheel paddle things ? Sometimes I accidentally flip the left [ changedown ] paddle and wonder why the engine is screaming and i'm only going at 30 mph


And what does the gearbox indicator in the dash say when this happens, is it in "D" or "2" "3" "4" "5" ?

 

[Dudeman]

I'll try shifting into neutral today when I drive. (Hadn't thought to try that. Good call!)

I also don't have paddle shifters on mine, just the Auto-Stick. It stays in "Drive" all the time but I'm aware that the Auto-Stick can be accidentally engaged. The issue happens every time I take my foot off the gas so I don't expect that to be the problem but I'll pay extra close attention.

 

[hofb99]

that does not sound normal. I'd find a different dealer.

^^^ +1

 

[Dudeman]

Well, I did some experimenting and found that shifting into neutral while coasting eliminates that drag that I'm feeling.

Got to find a better servicer.........

 

[silver06hemic]

Find a better dealer...with a Starscan or Starmobile unit...plug it in and see if you can replicate it. I would pay very close attention to your torque converter lockup position, the starscan will tell you the lockup state being commanded by the TCM, it should unlock at a certain point in deceleration, doesn't sound like it is to me. Could be a duff converter, but chances are the TCM telling it what to do are the issue. You should have them wipe the adaptives (imbedded one's, not surface ones Diablo does) and do a forced relearn with the tool.

Before you start any of that check the fluid level properly, if it's overfilled they can have the same symptoms...

Sent from AutoGuide.com Free App

 

[Dudeman]

Good advice. Thanks.

 

[Dudeman]

I found a different dealer. Have an appointment on Saturday. In the meantime, the issue is definitely getting worse. I'm getting hard up and downshifts as well as a nasty "clunk" when I change gears. These symptoms just started happening yesterday.

Fluid level is OK.

 

[silver06hemic]

You have a dipstick and a way to read transmission temp?

Sent from AutoGuide.com Free App

 

[Dudeman]

A friend of mine runs an independent repair shop.

 

[silver06hemic]

A friend of mine runs an independent repair shop.

Perfect! Just want to make sure it was done right with the chart amd temps... I've seen them a few millimeters over due to being checked 'cold' or 'hot' and then good gears and not shift, judder, thump on downshift...you name it...these nag 1's like their fluid just right!

Sent from AutoGuide.com Free App

 

[300GBC]

I have a potential concern with my 5-speed transmission in my 2013 300c.

It shifts rough compared to the other examples of the same car that I have driven and it seems like it holds gears too long before it will downshift.

When I remove my foot from the accelerator, the car slows down rather quickly and doesn't coast smoothly. It acts like it not in the appropriate gear for the vehicles speed.

When it does downshift, the engine revs and growls and the RPM's spike harshly.

Now, I stopped by the dealer service center yesterday and the guy I asked about it said it was "completely normal" and a "cool feature of the vehicle". He explained that the car is shutting off the fuel injectors and using the weight and momentum of the vehicle to slow it down.

He never looked at the car, drove it or asked any questions about the circumstances of my concerns. It took him about thirteen seconds to determine that there was nothing wrong with my car.

I have read about others that have had rough shifting from the 5-speed transmission and it seems like resetting the shift points and re-flashing the control unit has solved their problems.

Should I take my car to a different servicer?

Also, I have owned the car for about six weeks and it has about 20,000 miles on the clock. I assume that should be ample time for the computer to learn my driving habits.

Thoughts?

I'm actually experiencing something similar! I have a 2011 300c and I have noticed that when I let off the accelerator there is a serious drop in speed that I never remember having when I owned my 2008 300c. I thought maybe this was something normal in the 2nd gen models. You are the first person other than myself that I have heard mention this issue. I have to double check on the shifting points but for some reason I think I do recall the over rev when downshifting....

 

[Dudeman]

Hopefully you get better service than I have thus far. I know that this behavior isn't normal.

I should know more this weekend.

Edit to ask: Have you tried shifting into Neutral while coasting? Mine rides smooth as can be once I do that. It helped to rule out any other possible causes for the drag, too.