tayl0rmade

Just bought an 05 AMG on Friday and I've run into my first "uh oh". The car's got 60k on the clock, two prior owners, and has been babied and serviced regularly (I have receipts/records).

When taking off from first gear, there's a slip and clunk right out of the gate, at 10mph. After it gets through that, it runs like a raped ape. It's a definite problem where it feels like it's slamming into gear. It happens in manual, comfort and sport settings and it doesn't happen all the time. It's enough that it's freaking me the heck out though. If you are able to "get on it" a little bit out of the gate, it's ok, but if you're in a parking lot or behind someone in traffic, it's no beuno.

My wife has the car up in North Carolina now (drove up yesterday with no problems) and is scared to drive it any more. It did it to me twice while I was driving it, and I made a mental note that we were going to need to get it looked at, but it only happened twice in a three day period and it wasn't enough to be freaked over.

It recently had the B service done and no problems were noted. I bought it from a private seller, who I talked to and, of course, he'd never heard of it before and it'd never happened to him before. I actually believe him because I drove it for two days before it happened to me.

So, Cliff's Notes:

60k miles
Slipping out of first gear and slamming back in at 10mph/1200 RPM
Does it in all modes
No audible noises
Car runs great once it gets past that
Doesn't happen every time.

Any suggestions where to start?

betrezra

I would try to run STAR DAS and see if codes present.

A good indie can run this diag for you.

Bad mass air meter can do weird things like this as well and be intermittant.
Or perhaps transmission....... when was fluid changed last?

GL.

tayl0rmade

Thanks for the response. That's the one thing I can't validate as having been done. Service records every 20k but I don't see that the tranny was ever serviced. She's out of town this week, but I was going to look for either a import shop or just tell her to go to the nearest Benz dealer and have them get in to it.

Am I looking at around $250 to have the flush/fill? Does the filter need to be changed at 60k?

Thank you. We had a maintenance free 07 C series and love this car... just don't want to do any further damage.

DxbStew

It could also be the transmission conductor plate.

tayl0rmade

Ok, so we'll start with cleaning the MAF sensor. That I can walk her through doing over the phone... if no joy there, I'm researching reputable German shops in the Charlotte area as well. Thanks again for the input, keep 'em coming.

tayl0rmade

If it were the plate, wouldn't that be all the time though?

DxbStew

Not necessarily.
It would depend on how bad the plate was. My plate caused intermittent problems.

Your best bet is to get your fault codes read.

tayl0rmade

I see, thanks for the input. She's on her way to the shop now. Fingers crossed, we haven't even paid the taxes on this car yet.

tayl0rmade

Sooo got an update from the indy shop. There are no error codes and no problems with the transmission. It's operating as it's supposed to, but he feels the torque converter is either engaging when it's not supposed to or not when it is supposed to. Honestly I kind of tuned out after he said everything looked good and my cell phone connection wasn't the best. Fluids look good, no metal shavings in the pan.

So he wants to reprogram the TCM but wants to do it when it's cold so we're leaving it there overnight.

The good news is he said he didn't think we're doing any damage to it, so that's a plus.

GatorMB

Looks like you are getting close,

Other considerations would be a trans memory reset.
B inspection redone, the symptoms can conclude the drive line.
Driving (old) habits in a new or different vehicle will seem to create mischief problems as well.)

Cheers, Gator





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tayl0rmade

Alright, so no good news to report. The shop reprogrammed the TCM twice along with the transmission memory reset twice to no avail. The torque converter is designed to engage between 10-15 mph slowly (or ease into it I guess) and mine's just instant on slamming into effect. There's nothing wrong with it, it's not hurting anything, it's just annoying.

So, I suppose no news is good news in this case, but now we just need to live with something annoying... I already have experience with an ex wife, so we should be all set.

When it gets home, we'll take it to our trusted German shop just to make sure they agree. Thanks for the input and the advice offered here!

mb techman

.

tayl0rmade

Will do thanks!! He reprogrammed (or reset) two things and perhaps I didn't get the second one right. Thanks for the clarification!

GatorMB

Hey taylormade,

This is one of those car problems that most of us might not have ever experienced. (I am one of them)
The replies here aren't real strong.
Its real hard to tell someone where to throw money chasing this kind of problem.
I have guessed pretty good in the past and a computer program is not solving this problem.

1st hunch is the torque converter, Its internal 1 way clutch might be failing upon initial lockup. you will have to get harsh with the car and try to get a thump in reverse. (or take-off in 2nd or 3rd from a start) report conditions.
Driveline thumps would be noticeable at any speed when braking and accelerating.
Engine and trans mounts (bad) will give bad vibes in the steering wheel and floor boards as well. The B inspection would have revealed this.

Good Luck, Cheers

Gator

PS: Trans fluid leaking back into the TCU is a very common problem and is discussed in many forums Its worth investigating.

tayl0rmade

Thanks Gator, I will investigate it for sure. It's the torque converter for sure and the owner of the shop worked on it for a day and a half. He called his buds over at the Mercedes dealership and they said they've had a few cases where it just won't go away no matter what parts are replaced (short of the entire transmission). They relayed a few stories of replacing torque converters, computers, etc, all to no avail.

It'll be interesting to see what my local guys say when the car gets back to Tampa. Thanks again for the assistance and advice!

VIPclk320

reading the first post im 99% sure its your conductor plate inside the trans. a lot of times it doesn't through any kind of a code and it feels like your transmission mount has gone bad but its actually the conductor plate which is gunned up. also many palaces are going to tell you that benz doesn't selll the plate separate anymore but they actually do and its about $350.

tayl0rmade

Thanks for the reply! I thought for sure it was the plate as well, but the guys at the shop didn't seem to think it'd help. Or I guess their fear was tossing money at it, replacing parts, and having it not fix the problem. This was relayed from some guys at the local dealership that had seen the problem a few times before.

The car is back home now and I've had a chance to drive it. It's very odd. It doesn't do it every time, and I've noticed that it doesn't do it as violently in Sport mode as opposed to Comfort mode, where it would make you spill your drink. There's no noise, no grinding, no clunk or thud, it just stalls for a split second, and then bam. I drove it 30 miles each way last night and it did it exactly once in Sport mode for me. Otherwise this car runs beautifully. I'll be taking it to our local, trusted guys this week.

GatorMB

The torque converter:

The converter has two vanes that couple the engine to transmission with hydraulic means.
Once the clearances start to increase between the vanes - The lockup coupling time increases. With the symptoms and history of computer diagnostics seemed to point to a mechanical failure internal to the converter.

The computer is attempting to lock up the converter as a 1:1 ratio at 15 mph as explained earlier in this post. I suspect the hydraulic coupling might not have been evident when the computer is controlling.
One way clutches are utilized for reverse on planetary gears internal to the trans.
Lock up clutch assemblies are built into torque converters for the 1:1 coupling normally after 45mph (But this is Benz) 15mph is quite an accomplishment.
The conductor plate houses the interface between the computer and the hydraulic control circuits. With the many advancements in computer technology it still takes a technician with some gages to detect mechanical failures internal to the transmission. The conductor plate has corrected many issues with shift quality as well and is not real expensive for a seasoned DIY guy/gal.

Hope this helps a bit and thanks for sharing this with us.

All the best,
Gator

tayl0rmade

Oh man, I certainly appreciate the lesson and the time it took for you to convey this information! I'm going to take it over to the shop either tomorrow or Friday and have them drop the pan and give it a once over. I drove it around a bit today and it drove fine with no slipping at all in Sport mode.