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Discussion Starter #1
So today was the first day that was perfect weather in Dallas, so i took it out for a ride in the AM.

A friend told me (uh oh) that downshifting on curvy roads allows you to have a lot of power...

So i shifted my 350 into 4th gear (it's really only limiting it to the 4th gear right?)

that didn't work well, apparently it felt like when i stepped on it, it just stayed in 2nd gear.... (the RPM went way up but i was still at 25 MPH).

and even when i put it back to D (automatic) it still did the same thing...

I would step on the gas and the it felt like the car was stuck in a low gear (6000 rpm at 20 MPH).

I stopped on the side of the road and turned the engine off and restarted the car, and now everything works fine...

Should i be concerned? Is there any truth in having low gear on curvy roads?


Thanks guys
 

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Lower gear helps you slow down into the curve while at the same time sets you up to have more torque in leaving the curve.

The action of the transmission is concerning. If it happens again, you'll need to have it checked out by the dealer. The electronics module may need to be reset or replaced. That's what happened to me.
 

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If you just want the best acceleration for a short time, hold the shifter to the left for a couple seconds. This will put you in the optimum gears for acceleration. You can sometimes be surprised just how low the best gear is for acceleration.

Keep a close eye on your car though, since you felt something was wrong.

Go back to drive by holding the shifter to the right a couple seconds.
 

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I have the same problem on my 55 as well...Seems to get stuck on random gears, and on different times of the day...first time it was stuck in what appeared to be 2nd (extremely high rpm for even low speeds), and the following was more like 5th (acceleration from the light was horrible)....stopped counting at this point

Pretty much the same solution, pull over, cut everything off, restart.

I have an appointment next week to deal with what appears to be dead pixels on my lower center gauge...guess i'll had crappy annoying transmission issues to the list
 

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Discussion Starter #5
Thanks for the response guys, i will keep an eye out and update as it happens more (so far it hasn't happened again).
 

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Founding Member #2 2008 SLK55 AMG
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I have the same problem on my 55 as well...Seems to get stuck on random gears, and on different times of the day...first time it was stuck in what appeared to be 2nd (extremely high rpm for even low speeds), and the following was more like 5th (acceleration from the light was horrible)....stopped counting at this point

Pretty much the same solution, pull over, cut everything off, restart.

I have an appointment next week to deal with what appears to be dead pixels on my lower center gauge...guess i'll had crappy annoying transmission issues to the list
Thanks for the response guys, i will keep an eye out and update as it happens more (so far it hasn't happened again).
Sounds like a sensor/conductor plate problem.
 

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Hi !

This is the first I hear of this automatic downshifting feature... but is it only on the R171?

I have an R170 and was unable to do it... maybe I'm doing something wrong.

A.
 

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Hi !
This is the first I hear of this automatic downshifting feature... but is it only on the R171?
I have an R170 and was unable to do it... maybe I'm doing something wrong.
A.
I don't know dude, check your manual, that's how i learned about it...am still weary of doing it, it knocks you down a few gears, kicking up your rpm to the high 4000s.
 

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estimate on how much it costs to fix if i don't have warranty?
If it happens again, take it in to the dealer for diagnosis to be sure, but if it is the "conductor plate"/ECC Module, then it should be no more than $1,200 including the diagnosis charge.
 

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estimate on how much it costs to fix if i don't have warranty?
The conductor plate/controller was bad in my car. The new cp-c wouldn't communicate with the existing valve body, so an entirely new valve body/cp-c had to be installed. The total cost, including the inspection, was $2,000. My warranty paid $1300.
 

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I don't know dude, check your manual, that's how i learned about it...am still weary of doing it, it knocks you down a few gears, kicking up your rpm to the high 4000s.

Well.. I could not find it in the manual but tried it anyways... and it does work on r170.

Went for a small run through the everglades and it was a blast !!! really interesting behaviour and it brings out the sporty side of the car.

If you feel a bit weary, don't fret, just try it going from what would be D while going slow and progressively trying it until you get the feel for it.

I admit it was a bit awkward on the downshifting feeling but if you start trusting it, then your grip on the turns is vastly improved.

Enjoy !
:rb
 

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A similar thing happened to me in my R171 about four weeks ago. I'd not long had the car and decided to be a bit 'clever' and play with the gear-shift paddles, even tho I had no idea what I was doing. The gear stuck in second and wouldn't change out if it. My solution was like yours. I stopped at the side of the road, turned off the ignition, waited a few seconds then turned it back on again. Thankfully since then I've had no other problems.
 

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A similar thing happened to me in my R171 about four weeks ago. I'd not long had the car and decided to be a bit 'clever' and play with the gear-shift paddles, even tho I had no idea what I was doing. The gear stuck in second and wouldn't change out if it. My solution was like yours. I stopped at the side of the road, turned off the ignition, waited a few seconds then turned it back on again. Thankfully since then I've had no other problems.
Uh, you should probably get it to the nearest MB dealer and have them run a diagnostic on just the trans. Mine did this the first time on 3/26/11 and the second time 4/30/11...really, get it checked-out...
 
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Discussion Starter #16
Just to establish a baseline (med school is so busy right now i don't really have time to go to the dealership, i also hate my dealership since the last time i was in they treated me like ****)

If you floor the peddle, it's normal to have it go up to 5000-6000 rpm before it shifts gears right?

does anyone have a shot of the RPMs while going from 0-60 while flooring it?

I have had no further problems with the transmission or gear getting stuck.
 

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if you floor it, and push past the resistance (kickdown), it'll drop it a gear instead of just accelerating in the higher gear it's in, which is why you saw the rpms shoot to 5000 - 6000
 

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if you floor it, and push past the resistance (kickdown), it'll drop it a gear instead of just accelerating in the higher gear it's in, which is why you saw the rpms shoot to 5000 - 6000
Technically correct, but not always - the "kickdown" button on the R171 is just a button and spring connected to air. In theory I think it's just to let you know you are really at the floor! :)

From a stop, if you floor it in S mode you will just about red-line before every shift UNLESS esp kicks in. If you are in "manual UP" mode, it will red line before shifting. In you are in "M" mode, you'll hit the rev limiter.
 

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Yep, sure enough my Conductor plate had to be replaced, along with a bunch of stuff in there, i think i heard valve something...luckily, my Carmax warranty will cover it ($2200 parts and labor), i just need to pay for the transmission filter ($30) and my deductible.
 

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Glad to hear it's getting fixed. My warranty didn't cover the removal and testing of the "parts".
I'm puzzled why you have to pay for the filter and not the trans fluid (assuming they use NEW fluid!) and the weir tube.
 
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