SL55/63/65/R230 AMG: Transmission issue after K2 upgrade
05-27-2006, 11:54 PM
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Transmission issue after K2 upgrade
hey guys,
I jsut got my K2 upgrade and I noticed couple issues with the transmisson. The car sometime shifts into neutral after the transmission tries to downshift to a lower gear. It doesn't shift back into a gear until I pulled over and put it back into P and back into drive again. Has anyone experienced this issue before? It seems like this only happens when I first start the car. Maybe the transmission hasn't been properly warmed up?
2nd issue, when I'm doing a rolling start from around 10mph, the car downshifts but bogs down a little bit. I heard when the car bogs down it puts lots of stress on the transaxle. Is this true? Does the SL65 come w/the same transmission as my 55? If so, I wouldn't need to worry about the engine's torque overpowering the transmission right? Thanks
Any advice is greatly appreciated. Thanks
Andy
I jsut got my K2 upgrade and I noticed couple issues with the transmisson. The car sometime shifts into neutral after the transmission tries to downshift to a lower gear. It doesn't shift back into a gear until I pulled over and put it back into P and back into drive again. Has anyone experienced this issue before? It seems like this only happens when I first start the car. Maybe the transmission hasn't been properly warmed up?
2nd issue, when I'm doing a rolling start from around 10mph, the car downshifts but bogs down a little bit. I heard when the car bogs down it puts lots of stress on the transaxle. Is this true? Does the SL65 come w/the same transmission as my 55? If so, I wouldn't need to worry about the engine's torque overpowering the transmission right? Thanks
Any advice is greatly appreciated. Thanks
Andy
05-28-2006, 03:20 AM
#2
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Andy,
I have a 2005 SL600 with the RennTech ECU upgrade. Something similar has happened to me once. I was getting onto an on-ramp to a freeway and floored the accelerator. I had a small moment of deceleration (possibly turbo lag) and then a huge downshift to redline. My car made a loud sound and then it wouldn't accelarate anymore at all. It went into neutral even thought the transmission was in drive. I drifted to the side of the road and it wouldn't go even if I shifted back to park then to reverse or drive. I was going to call a tow truck but then I figured I would shut the car down and restart it again. After I did this the car worked. I spoke with the head mechanic at RennTech (who use to work as a mechanic at a Mercedes dealer) and he told me this was a safety mechanism so the transmission would be protected. Something about the computer is still learning and adapting and it rarely gets confused between gears and goes into this mode for protection. Sounds to me you had a similar thing happen but for some reason you did not have to shut the car down to use it again. I wonder why? Yes I do believe both our transmissions are the same as the SL65 and should handle the torque. My dyno showed 598 ft. lbs's to the rear wheels (about 720 at the engine). From what I've read, our transmission should handle this. Hope this helps.
Larry
I have a 2005 SL600 with the RennTech ECU upgrade. Something similar has happened to me once. I was getting onto an on-ramp to a freeway and floored the accelerator. I had a small moment of deceleration (possibly turbo lag) and then a huge downshift to redline. My car made a loud sound and then it wouldn't accelarate anymore at all. It went into neutral even thought the transmission was in drive. I drifted to the side of the road and it wouldn't go even if I shifted back to park then to reverse or drive. I was going to call a tow truck but then I figured I would shut the car down and restart it again. After I did this the car worked. I spoke with the head mechanic at RennTech (who use to work as a mechanic at a Mercedes dealer) and he told me this was a safety mechanism so the transmission would be protected. Something about the computer is still learning and adapting and it rarely gets confused between gears and goes into this mode for protection. Sounds to me you had a similar thing happen but for some reason you did not have to shut the car down to use it again. I wonder why? Yes I do believe both our transmissions are the same as the SL65 and should handle the torque. My dyno showed 598 ft. lbs's to the rear wheels (about 720 at the engine). From what I've read, our transmission should handle this. Hope this helps.
Larry
05-28-2006, 12:57 PM
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thanks larry
Originally Posted by france2112
Andy,
I have a 2005 SL600 with the RennTech ECU upgrade. Something similar has happened to me once. I was getting onto an on-ramp to a freeway and floored the accelerator. I had a small moment of deceleration (possibly turbo lag) and then a huge downshift to redline. My car made a loud sound and then it wouldn't accelarate anymore at all. It went into neutral even thought the transmission was in drive. I drifted to the side of the road and it wouldn't go even if I shifted back to park then to reverse or drive. I was going to call a tow truck but then I figured I would shut the car down and restart it again. After I did this the car worked. I spoke with the head mechanic at RennTech (who use to work as a mechanic at a Mercedes dealer) and he told me this was a safety mechanism so the transmission would be protected. Something about the computer is still learning and adapting and it rarely gets confused between gears and goes into this mode for protection. Sounds to me you had a similar thing happen but for some reason you did not have to shut the car down to use it again. I wonder why? Yes I do believe both our transmissions are the same as the SL65 and should handle the torque. My dyno showed 598 ft. lbs's to the rear wheels (about 720 at the engine). From what I've read, our transmission should handle this. Hope this helps.
Larry
I have a 2005 SL600 with the RennTech ECU upgrade. Something similar has happened to me once. I was getting onto an on-ramp to a freeway and floored the accelerator. I had a small moment of deceleration (possibly turbo lag) and then a huge downshift to redline. My car made a loud sound and then it wouldn't accelarate anymore at all. It went into neutral even thought the transmission was in drive. I drifted to the side of the road and it wouldn't go even if I shifted back to park then to reverse or drive. I was going to call a tow truck but then I figured I would shut the car down and restart it again. After I did this the car worked. I spoke with the head mechanic at RennTech (who use to work as a mechanic at a Mercedes dealer) and he told me this was a safety mechanism so the transmission would be protected. Something about the computer is still learning and adapting and it rarely gets confused between gears and goes into this mode for protection. Sounds to me you had a similar thing happen but for some reason you did not have to shut the car down to use it again. I wonder why? Yes I do believe both our transmissions are the same as the SL65 and should handle the torque. My dyno showed 598 ft. lbs's to the rear wheels (about 720 at the engine). From what I've read, our transmission should handle this. Hope this helps.
Larry
05-28-2006, 08:53 PM
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Originally Posted by Xeron
However, I'm stock. I pulled over, put in park then it was able to engage.
05-30-2006, 12:42 AM
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2008 C300 Avantgarde
This too has happened to me (on a W210 E55) where the transmission has gone to neutral even though i am still driving in "D". I find it mainly occurs if i drive it hard. Say i am heading into a turn, i would accelerate, ease off accelerator slightly to wash off speed and just as i come out of a corner, if i punch it WOT, the transmission becomes confused and drops into neutral gearing, even though transmission is still in "D".
It has never happened whilst driving smoothly or "normally". Only on hard acceleration or if i play around with the transmission and shift manually whilst punching the accelerator. It also tends to be made worse with rapid changes in lateral forces, say driving hard into and out of round-abouts and bends.
There seems to be no cure for this anomaly in our 5 speed transmission and once the transmission goes into "error mode", I usually try and manually shift down to 1st gear to see if it re-engages before bringing it back up to "D". If not, I pray that there is minimal traffic around so that one can get to the side kerb to fully stop, put gear into "P" and then back to "D" and drive off again. I find this bug in the transmission most dangerous if it occurs in a multilane freeway and if you are stuck in the overtaking lane. If you lose gear; car naturally slows down; but with other cars passing you at high speed it can become quite dangerous trying to merge and get to the breakdown lane.
I also find it recurs less frequently following one of these episodes by resetting the transmission's memory on reaching my destination by either disconnecting the battery or doing the ignition/accelerator method (discussed in other threads). This should wipe out any transmission fault codes and i find that it takes longer for transmission to "play up" again.
i have spoken to mechanics from Benz dealership, and they think it may be a faulty transmission module or that transmission fluid is getting old. And they suggest that even though Benz states that the transmission fluid does not need replacing for 60-80K miles, it may not be a bad idea to have it replaced every 30K miles to be on safe side. I have not tried any of the above dealer's sugggestions yet as i still believe it is an inherit fault in these torque loving 5 speed transmission boxes.
It has never happened whilst driving smoothly or "normally". Only on hard acceleration or if i play around with the transmission and shift manually whilst punching the accelerator. It also tends to be made worse with rapid changes in lateral forces, say driving hard into and out of round-abouts and bends.
There seems to be no cure for this anomaly in our 5 speed transmission and once the transmission goes into "error mode", I usually try and manually shift down to 1st gear to see if it re-engages before bringing it back up to "D". If not, I pray that there is minimal traffic around so that one can get to the side kerb to fully stop, put gear into "P" and then back to "D" and drive off again. I find this bug in the transmission most dangerous if it occurs in a multilane freeway and if you are stuck in the overtaking lane. If you lose gear; car naturally slows down; but with other cars passing you at high speed it can become quite dangerous trying to merge and get to the breakdown lane.
I also find it recurs less frequently following one of these episodes by resetting the transmission's memory on reaching my destination by either disconnecting the battery or doing the ignition/accelerator method (discussed in other threads). This should wipe out any transmission fault codes and i find that it takes longer for transmission to "play up" again.
i have spoken to mechanics from Benz dealership, and they think it may be a faulty transmission module or that transmission fluid is getting old. And they suggest that even though Benz states that the transmission fluid does not need replacing for 60-80K miles, it may not be a bad idea to have it replaced every 30K miles to be on safe side. I have not tried any of the above dealer's sugggestions yet as i still believe it is an inherit fault in these torque loving 5 speed transmission boxes.
