SL/R230: Transmission
Thread Starter
Member
Joined: Aug 2023
Posts: 230
Likes: 21
2007 MBZ SL550
Transmission
I have a question that hopefully is not the regaining of the end of my transmission. I was getting onto the FWY on Sunday. I punched it as I usually do to get around people driving under the 55 or 65-mile speed limit that clogs up the highway and makes it nearly impossible to drive on when, and this is the first time I have experienced it, that it felt like the car dropped into neutral because when I was looking at the tachometer because I heard the car rev to highly, and was almost redlining. Usually, I punch it, and the car goes like a bat out of hell with no perceptual redlining. Also, the car was all warmed up and not cold at that point. So, I thought I would ask the rest of you what this might have been.
Thank you.
Thank you.
Senior Member
Joined: May 2020
Posts: 458
Likes: 55
From: North Carolina, USA
2004 SL500AMG, 2003 SL500 USA
It is probably the TPS (Throttle Position Sensor) on the accelerator pedal assembly. The TPS is not serviceable. Replace the pedal assembly with a used one from ebay, or an expensive new one. It is attached to the floor with a 10mm nut.
MBWorld Fanatic!
Joined: Aug 2020
Posts: 1,340
Likes: 366
From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
An out of range value on either channel of the accelerator pedal or the two values not in agreement will throw a code and put the car into limp mode (2nd gear, I believe). Cycling the key will reset the limp mode back to normal, but a stored code will remain.
Super Member
Joined: Sep 2021
Posts: 546
Likes: 118
From: Ann Arbor, MI
2004 SL600
Ha, I had the exact same problem several weeks ago and reported it here at this link:
https://mbworld.org/forums/sl-class-...eleration.html
I know for sure I did not go WOT as I am still shaking things out with my new engine. Also, I did not have to cycle the ignition; once I slowed to 5 mph or so, the trans then shifted perfectly as I sped back up. Unfortunately I did not immediately check for codes and soon disconnected the battery as I am frequently fiddling with the car.
When I Googled my symptoms, I found, maybe on a Chrysler site, that this was the exact symptom of a bad conductor plate in the trans. I already ordered and received a 722.6 Conductor service kit from FCP Euro. As someone very comfortable working on automatic transmissions, I will install it myself; I'm actually researching mods to make to the valve body when I have it out.
Still, I greatly appreciate the suggestions that an accelerator pedal fault can lead to this or a similar symptom.
https://mbworld.org/forums/sl-class-...eleration.html
I know for sure I did not go WOT as I am still shaking things out with my new engine. Also, I did not have to cycle the ignition; once I slowed to 5 mph or so, the trans then shifted perfectly as I sped back up. Unfortunately I did not immediately check for codes and soon disconnected the battery as I am frequently fiddling with the car.
When I Googled my symptoms, I found, maybe on a Chrysler site, that this was the exact symptom of a bad conductor plate in the trans. I already ordered and received a 722.6 Conductor service kit from FCP Euro. As someone very comfortable working on automatic transmissions, I will install it myself; I'm actually researching mods to make to the valve body when I have it out.
Still, I greatly appreciate the suggestions that an accelerator pedal fault can lead to this or a similar symptom.
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MBWorld Fanatic!
Joined: Aug 2020
Posts: 1,340
Likes: 366
From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
What we are saying is that this is a common problem that leaves very specific codes behind. Scan and see if you have codes for accelerator pedal values out of range. If so, shim it to limit travel, or replace it.
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Joined: Sep 2007
Posts: 1,481
Likes: 310
95 SL600
I have has a pedal that overextends when floored. When it sees parameters outside of the normal ones it sent the engine into a dropped cylinder limp mode. That does not allow the car to “redline”, it limits the power to almost non existent by limiting rpm. It doesn’t sound like what happened in your car.
Your car has a 722.9 transmission which can be problematic in the early years, my early car has a722.6, but I would suspect the pedal malfunction would be the same result. If yiu don’t have a proper diagnostic tool for these cars, yiu should get one, they are not very expensive and will lead you to better diagnosis,
Last edited by cdk4219; Jan 21, 2025 at 03:30 PM.
