Jerking when downshifting
going uphill at slow to medium speeds I occassionally notice a jerky downshift, nothing violent but enough to be different than usual. I also notice a hesistation (kind of like slipping) shift when the engine is cold. I need to concentrate to notice it though. But as for the problem others I having, I can confirm that the car exhibits this off and on bucking jerking as if you are driving a manual car in too high of a gear.
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After about 5 minutes on the road, the car starts having a problem downshifting,,, a hard jerk when slowing down, between 20-15mph. Also, the car idles fine at stoplights, but if you put it in PARK, the idle jumps to 10-12 rpms and stays there. I took it in last week, they said it was fixed (bad front wheel sensors). NO FIX. i took it back and they tell me it needs a software update for the transmission. I get the car back today so I will let you know if this fixes it.
My advisor at house of import didn't even know what the pulsation dampner retrofit was (still doesnt). Can you recommend a service advisor there?
Thanks.
I just wanted to give everybody with the jerking problem a further possibe cause that I picked up on a German forum. Apparently, there is a problem with coolant fluid leakking into the transmission and mixing with the transmission fluid. This then gradually damages the friction pads/linings of the torque converter lockup clutch. Remedy is to flush the transmission with 15 quarts of fluid or install a new one. Just wanted to let everybody know that if a software update doesn't solve the problem, this might.
It is very noticable early in the morning when I drive down the hill by my house. Feels like something is gripping, kinda like when you let go of the clutch too early on a stickshift.
Somebody on benzworld says dealer replaced his transmission "module" and fixed the problem. I couldn't even duplicate the problem the dealer let alone convincing my SA there is a problem. He just says "oh it's a Mercedes, they all shift hard." What a full of turd.
Just for grims I tried driving around in the C-"comfort" mode, and no longer experience this jerkieness in downshifting. If anybody is still experiencing this issue, can you try the C-mode and report back?
I've been experiencing the same problems as you guys, ever since shortly after I bought my car from House of Imports (5/04)!
For me, the "jerking" (engine surging) occurs both while accelerating AND decellerating. It only happens at slow speeds (below 10mph) and when the transmission is in the default "S" (sport) mode.
It literally feels like riding in a car w/manual transmission, and the car kinda hesitates for split second, like its about to stall... and then hits the gas to prevent it, causing the car to "jerk"/surge/lunge forward.
You can skirt this problem by driving in C-mode all the time (although this is an unacceptable remedy!). I find myself having to do this when driving around VIPs, to save myself from the embarassment of this problem (50k+ car that rides like its being driven by a teenager who doesn't know how to drive stick-shift... even though its an automatic!). Since "C"-mode ignores the 1st gear, I'm assuming its a problem with the 1st gear on the transmission. Defective shift program maybe? (I'm not very knowledgable about the technical terms.)
It happens intermittently, but lately its been happening pretty often (maybe because of the warmer weather??). I'm at the point now where when it starts happening, I can almost force it to happen... simply by depressing the accelerator slightly and releasing it, and then quickly depressing the accelerator again slightly. In fact, it occurs the most when I'm crawling along in heavy traffic on the fwy, and accelerating in such a fashion.
Engine temperature doesn't seem relevant in my case. I can be motoring along for about 30 mins, then hit some traffic on the fwy, and then *BAM*... the engine surging begins.
I've gone at least 5 times to the dealer to get this fixed. The first time, my SA came back to me and told me that MercedesBenz was aware of the problem and was working on a "Parking Lot Software Update". Everytime I went in for another problem, I asked if the update was released yet, and each time I was told "not yet". Most recently, I went back again about 2-3 months ago for scheduled maintenance. I was given a new SA (my previous one doesn't work there anymore). When I asked the new SA about it, he didn't have any idea about what I was talking about. He even called a tech while I was there, and the tech didn't know anything about a "Parking Lot Software Update" either. And then they couldn't even "replicate the problem" that time, so now I'm all the way back at sqare one.
To the poster who reported that he got a software update to fix the problem:
After extensive driving, has your problem been remedied? I ask this, because I was also given numerous "software updates" and they didn't do jack for me. But if in fact, your software update did fix your car's problem, then perhaps the elusive "Parking Lot Software Update" really does exist and has been released... Please let us know how your car's doing now!
Last edited by charliek; Apr 8, 2005 at 09:39 PM.
This may be something entirely different from what is described above, but I thought it was worth mentioning.
Last edited by larryssf; Apr 9, 2005 at 02:02 AM.
The "jerking" though is definitely pronounced, and definitely not normal.
This may be something entirely different from what is described above, but I thought it was worth mentioning.
My car would surge when coming to a quick stop (ie. from 20-0) in heavy traffic. I was able to duplicate the problem and the shop forman performed a few adjustments. He reset the adaptive transmission programming, the found that some of my gears and the torque converter was out of spec. He readjusted those, and it's a lot better. The car still feels "confused" at times, but it's a lot more driveable now.


