edwinwalke

Then that is specific to the 7 speed Transmission. My 06 E320CDI starts in 2nd when in C mode. Manual also confirms. The high torque that the diesels develop make it easy to start in a higher gear.

fatherhood

I agree, it doesn't make sense that it would start out in 1st if you got more torque.
Way back in the 80s when I had several cars with low torque engines, first gen VW GTI and first gen Integra, you had to start in 1st because they'd stall out in 2nd, even if you were still rolling. Those cars were a lot of fun to drive when on the back roads but in stop and go traffic, with no AC of course, they were a horror show. Ahh to be young again.

DubVBenz

There is seemingly no benefit I can find with the S mode on the diesel. Holding out the RPMs in a gas car can provide some benefit, but our cars are pretty anemic at high RPM. The only difference I notice in S vs C is fuel consumption. Of course, I haven't tried any timed runs.

fatherhood

Just an update on this old thread. After several trips to the dealer and some research on their part. The newest transmission software update essentially disables the C/S button for the Bluetecs, although strangely it still changes the letter in the instrument panel. Apparently there was an issue with these engines building up soot on the filters and cats, remember this is according to the dealer, due to the engine spending too much time at idle. So to fix this issue they, Mercedes, decided to increase the idle speed and have the transmission always start in first gear. I'm assuming that the more aggressive engine braking regime is part of the fix as well, although the dealer's report did not mention that, but it makes sense to do this if your goal is to reduce the amount of time the engine spends at idle.
I'm not sure I buy this whole soot build up explanation because I have seen no mention of it any where. It seems far fetched that they would sacrifice comfort and safety to such an extend to fix a problem that hardly makes a blip. That being said, it does neatly address all of the issues I have with the transmission.

Has anybody else heard of this soot issue?

Are there any Bluetec owners who have not had there transmission software updated and notice a difference between C/S modes?

I'd like to get back to the point where the tranny starts out in second gear when in C mode and I'll take my chances with the soot build up.

pinebaron

That is interesting; I'll look up my service history. By the way I only drive in S mode, don't care much for C.

fatherhood

If you notice a difference you have not had the transmission update, according to what my SA wrote up.
Can you to verify that your car starts out in second gear when in C mode? If so, I'd be interested in getting that version of software.

DubVBenz

My car had the most recent update as of mid-summer 2010. There is still a difference (harsh downshifts are gone). If you're cruising at 40MPH and the RPMs are being held, just push C and it'll upshift. It's pretty obvious when already at speed, but I haven't paid much attention to it from a stop. I would be willing to bet your dealer is just bull****ting you so you stop complaining. I'm going to go with that theory until I see some official documentation.

Dealers are like IT shops, they try to talk over you and confuse you so you don't understand enough to think you know what you're asking for.

fatherhood

Do you mean a difference between C and M mode or difference in the harshness of the downshifts?

I've tried pushing the C/S button under a variety of driving conditions, with no apparent difference. In my other Mercedes, '04 C320 4matic, there is a clear difference between C and S modes. In fact I'm a little confused, you stated earlier in this thread "The only difference I notice in S vs C is fuel consumption.". That difference in fuel economy can be attributed to the fact that when you are in S mode you are probably driving more aggressively.

That is distinct possibility, I could take it to another dealer, but it's just not very convenient. Mercedes dealers are not exactly thick on the ground around here. I was hoping to get some insight from fellow Bluetec owners regarding the issues I'm having with this car. Those being; the car staring in first gear all the time, and what is in my opinion, and those of other people who've driven my car, an excessive amount of engine braking. Back in May you stated you had similar issues, have they been resolved with the updates?

Where would you even get documentation? The stealership claims only to have talked to someone in Mercedes.

In this case I have to give the dealer credit their story fits the facts neatly, that is if you buy the soot build up angle. I could try to contact MBUSA for confirmation, but chances are they are going back their dealer.
The other explanation for the first gear starting is that the diesel engines make too much torque. Then why pair it with a 7G transmission? Sounds like hokey engineering to me.
Going off an a slight tangent here, I've also heard that the too much torque argument when I expressed my desire to the dealer for a 4matic diesel E-class. This makes even less sense since the ML, R, and GL are all sold with the 4matic system. Hell, even the E is sold in Europe with the diesel and 4matic combination.
Enough ranting here, I would really like to hear from other Bluetec owners regarding the issues I listed above and specific fixes if any.

avbar

Well now that the weather has turned cold, my '08 E320 (miles: 60K) is experiencing a very hard downshift from 2nd to 1st (@7 mph) in the mornings when I'm coasting to a stoplight. The first one of the day feels like someone has rear-ended me. Everything returns to normal once the engine is warmed though. I've only had this car since July and have no idea what firmware version I have or how to do a reset. I drive in C mode, but the problem is there in S too. I think I'll look for an MB approved, cold weather transmission fluid to use when I have the tranny flushed this month and see if that helps.

DubVBenz

Engine braking while cold feels like this, it's an attribute of the diesel engine. When you let off the accelerator at low speed while cold, it feels almost like you're slamming on the brakes. This is normal.

A different issue is when coming to a stop it downshifts and jerks. This can be directly correlated with downshifting. The jerk to a stop from the above situation happens without downshifting. The bump you feel while downshifting is generally a transmission firmware issue that can be corrected.

Unfortunately, your car is still going to feel different at low speeds while cold compared to a gasser. This is the third diesel I've owned (others were 80s 300SDs), and they've all performed this way, even the bluetec.

mglomstead

Thanks for above info. I am proud owner of my first MB - an '08 E320 Bluetec. Love the car, but the first downshift of the day when cold is consistent with the aforementioned "clunk". I run in "C" mode, but will now try "S" to see the impact.

Thanks DubVBenz for the info on diesels "dragging" when cold. Did not realize this.

I called the local MB dealer regarding a transmission update, but they said they didn't list any service bulletins for my VIN. Can someone offer a service bulletin number please?

I'm going to try another MB dealer and will report back upon resolution - thanks.