Forgive me if this seems like a stupid question - and no I don't read manuals.

Does the 4 Matic or ESP in the E350 cause the car to downshift or maintain lower gear when the wheels sense slippage?


This morning the roads were pretty icey. I was driving to work and the car drove great, didn't slide, but it seemed like whenever I took my foot off of the gas, the car was downshifting to keep the speed down. I thought something was wrong with the tranny but when I got to areas that weren't so icey, it was fine. Hit ice again and again it downshifted.

So is there some feature in the car that causes it to maintain a lower gear on slippery roads? I noticed it does that going steep hills too.

 

Funny you mention this... Sometimes when I lift my foot off the gas suddenly and completely, it almost feels like the car applied the brakes because it feels like the cars speed decreased too much for my simple reaction to traffic ahead. Other times the car will coast.

 

the esp uses the cars abs and brakes to apply braking to the wheels that are losing traction to prevent skidding, so in theory the car will not accelerate as fast, never expierenced the down-shifting...

 

That happens to me all the time too. Like if I'm accelerating to get on the highway, someone slows in front of me, I let go of the gas and the car feels like it's decelerating. I find the tranny to be a bit flaky.

This morning though it felt like it was supposed to do that, not that it was by accident.

 

Predictive brake priming feature sets the brake pads closer to the the discs when the driver quickly releases the accelerator, for faster brake response – standard all models.

 

May be the result of 4-ETS (4matic Electronic Traction System), if one or more wheels start to slip sensors at each wheel can brake slipping wheels individually and rebalance power to the wheel or wheels with most traction possibly slowing the vehicle enough to cause the downshift you experienced

 

That's interesting thanks.

The tranny definately doesn't like cold weather. Have to warm the car up forever otherwise it thumps into the next gear if it's still cold. Is the tranny mechanical or electronic?

 

Possesed. Yeah, the 7 Speeds definitely do much better when thoroughly warmed up.

 

There are a few factors at play here.

I am pretty sure that all 4-matics are still the 5-speed tranny, so you can’t really blame it on it being the 7-speed (even though I have driven the 7-speed tranny models and I know what you all mean).

Most MBs used to delay up shifts when the engine is cold so that the catalytic converter could warm up sooner. I noticed that my 4-matic is much less likely to up shift when you let go of the gas when it is cold than when the engine is warm. Even my old 300E did not want to up shift and would immediately start stopping the car instead of shifting to the next gear.

All W211s will measure the speed at which you lift your foot off the throttle, but it will only pre-tension the brakes, not apply them. So if you are feeling some sort of braking it is the tranny. Perhaps Pre-Safe does something, but I don’t think so. I think that what you are experiencing here is that the transmission has actually learned how you drive and if you suddenly do something out of the norm, it might no up shift instead and remain in the lower gear just to avoid hunting gears. This might be because of spirited driving and then you change your stile to smoother driving.

Another feature that these transmissions have is that they will avoid up shifting if they just had to downshift. By this I mean that when I am going up a hill and I don’t downshift myself, the transmission will do it automatically of course, but then it will not up shift to higher gear like most cars when you ease on the gas pedal, it will wait until you crest the hill and then shift. It is quite uncanny to see how accurately the car knows you have reached the top of the hill and will up shift even though you do not let off the throttle. I have actually played around with this and it is a very cleaver feature. This is a great feature and prevents “hunting” when driving up hills. I should say though, the tranny will up shift if you are revving really high and you are still driving uphill.

I read somewhere that along with the anti-hunting mode, it also has a feature where the transmission will not allow shifts if you are turning. This is only for higher throttle turns and is certain scenarios, but I know the MB avoids shifting their gears when pulling some Gs on curves. This is done because you could suddenly loose traction on a curve if the engine and tranny shifting cause a jerk in the curve. I have tested this too and I have noticed that my car really does try to avoid making any shifts when I am accelerating hard and turning hard as well.

So to go back to the original observation, my 4-matic will behave the same in hot or very cold weather. I seriously doubt that MB thinks that downshifting is safer than using ABS brakes to slow down on slick roads. I think that it might have more to do that your engine is colder for longer periods of time and the tranny is just marinating gears longer. Or, it could be that you are driving more gently and normal, so the tranny is still prepared for you to give it gas and accelerate instead of up shifting and coasting. If you really want to coast and have the transmission up shift ASAP drive it in C mode.

These are just my observations, but I don’t think that the 4-matic has anything to do with this.

Steve

 

I have heard this from others but I have yet to experience any thumping or mistimed gear change from cold. Mine has behaved flawlessly since new.

 

Thanks again. I know part of my noticing these things is that I came off of an Audi that had an exceptionally smooth 7 speed tranny. The Benz is very good, and frankly did learn how I drive - "spirited" (I like that).

 

Nice write up SAguirre....

I have to say that with all the snow we have had this year in the Colorado Mnts, I just love having the 4matic system. Just last week I was driving over a mountain pass (Loveland pass) which was covered with snow and ice. I dont have snow tires (mistake) but the braking and traction control worked great. Uphill isnt usually a big deal, but downhill with sharp turns can be tricky. The thing I love is that the car seems to know how fast you need to go without constantly hitting the brakes, around 20 mph in this situation. I beleive this has to do with the SBC system as well as the ECT. I know a lot of people complain about SBC, but so far it has worked great for me.

 

I constantly drive up to Vail and I used to always take my Audi S6 since it is a stick shift and I have a lot of control. Not to mention, the intercooler and turbo are great. However, I have been using my E class in spite of it being significantly slower going up the passes. I find that the transmission is very smart and affords me great control. Also, when and if I get stuck in traffic I am driving an automatic.

Just to get up to the driveway of the house in Vail is a challenge, the 4-matic is simply superb because it does not lock the differentials and still let you turn very well. The SBC on my car has also been great. I have 35K miles on the brakes and still have over 60% of the pads left. However, my original Continental summer tires were totally bald by 22k miles. I thought that was strange.

I paid out-of-pocket to have my differentials and transmission fluids changed at about 25K miles. I know that it is “lifetime” fluid, but I tend to keep cars for a long time and I wanted the break-in debris out of the system. I just checked on my way to work today and the transmission shifted immediately after I let off the gas pedal. Also, just as smoothly as when it is warm. It was about 15 F outside, but my garage was bout 45 F. Either way, I try to keep the car under 2K RPMs when I first start driving and I never have any trouble making the transmission shift by 2k RPMs. I guess I should say that I have really gotten used to it and I am probably going to see it as one of the best transmissions I have had in a car so far. I think that one fluid change is a good precautionary thing to do if you are planning to keep the car for a long time.

Steve

 

Just to note... You've got the good old 5 speed. I think most of the cold weather & shifting gripes are 7 speed owners.

 

Barry, mine's a 5 speed.