I have a 2005 XFire Limited with an automatic transmission. Sometimes when I "step on" the accelerator, the transmission slips into neutral. It happens when I am rolling at around 30 MPH, then punch it to get up to 55MPH. (I hesitate using the word "punch", it is more like a little oomph".

Anyways, when it happens, I found that putting the gear shifter into Neutral and coasting will eventually allow me to put it back into drive and it catches back into Drive.

Of course, when I took it to the transmission repair shop, they could not replicate the problem.

I have seen a few references to this issue on this forum, but no specific fix.

Any ideas?

 

Check for a leak around the electrical connector plug on the side of the transmission. The first thing you want to do is check the fluid level. Even if it's just a bit low can cause that. It might also be the conductor plate is going bad.

 

My car does that too when the pedal hits the floor. I am guessing your traction was turned off also and it was more than a little "oomph"... It only happens when I am playing around with a bunch of wheel spin, never happened at the track or with the traction control on. It is Mercedes way of stopping you from wrecking the car... Want to do high rev burnouts get a mustang lol
Learn to control it and it will be fine!

 

I have had some other problems with the car, so other than adding some transmission fluids, I didn't address this problem. I did take it to a transmission shop for a free road test, and of course, he couldn't replicate the problem. And then winter hit.


This year, the transmission is slipping again, and I am getting a 0730 Improper gear ratio code. I will try to check the traction control, and transmission fluid. I have seen some other posts reference the I/C Pump, but I don't know where or what it is. They also reference the NAG1 Plug, which I presume is in the transmission.

 

The I/C pump applies only to the SRT6, is that what you have ?
The NAG1 plug is the transmission ( NAG1 - New Automatic Gearbox - 1 ) plug where all the wires enter the transmission, front passenger's side. They are notorious for leaking, the OEM O rings were not too good.
Fairly easy fix, and costs around $12 for the new plug body.

 

Thank you for your response. I don't have a SRT..it is a limited. I tested it with the Electronic stability control both on and off, and it still slips. It slips when I step on the accelerator, and then quickly let off. Again, I get the 0730 improper gear ratio code. Need to change the NAG1 plug.


And now the other problem I had last year has resurfaced. It won't start when warm. I now get a P0335...Crankshaft position sensor, which is the same code I got last year. I replaced last year, along with the RCM. It seems to be tied to the convertible top because the light on the console blinks when I have this problem.

 

By 'slips', do you mean the RPM increases, but the car does not accelerate as it should ?
Or do you mean when it changes 1-2-3-4-5 that it slips between gear changes ?

If the former, then sounds like the torque converter.
If the latter, then sounds like a sticking solenoid.

In my experience, when a NAG1 is working 100% correctly, you can barely tell when it changes gears.

 

When the "slip" occurs, I feel a hesitation and sort of a click, and then it is like it is in neutral. I can rev the engine, but the transmission is not engaged. It goes back into gear when I get to around 10 mph.

Also, I looked for nag1 plug, but could not find it. Do I need to get it on a lift?

 

You can search uTube for NAG1, there are many videos on changing the connector, as well as changing the fluid and the conductor plate assembly.

 

Here's a pdf file that shows links to 6 Utoob vids showing the whole process....

Mercedes 722.6 Transmission Shifting Problems - 6 part videos.pdf

 

Sound like the YAW SENSOR IT'S IN THE CENTER CONSOLE ABOVE THE TRANSMISSION