france2112

Hi,
I have a 2005 SL600 with Renntech ECU/Transmission upgrade. Yesterday I was racing a friend with a 2003 CL55 (I kicked his *** by the way) and during initial heavy acceleration my car went into some type of default setting leaving me unable to accelerate and essentially putting my car in neutral even thought I was in drive. This happened one other time. The only way to fix this is to come to a complete stop and turn the car off and then restart. This became very dangerous in traffic. The first time it happened I was accelerating on an onramp to an expressway and luckily was able to drift to the side and restart my car. Help!! What is wrong! Is this a total malfunction or does this happen to other people. Both Times I did have the traction control off and had a lot of tire spin. Please any info. or advice would be helpful as I'm afraid my car is damaged. No check engine light is on and the car seems to drive and shift fine after restart. Thanks!!

france2112

MBTech21

Get the fluid level checked- they will act like that if low.

prsmith777

A few others on this forum have had a similar thing happen to them. I dont remember anymore what they decided it was, but if I recall right, it was something to do with exceeding the torque limits. I think it is a safety feature to prevent you from tearing up the transmission. I seem to remember it happened on a modded 65 AMG as well. I mostly read the SL forum, so try searching there.

france2112

Thank you both for the reply. I'll check the transmission fluid but I recently had my brake recall fixed and they were suppose to have checked all the fluids as a courtesy.

MBTech21,
Can you tell me if this is a protective mechanism? When this happens does it cause any permanent damage to the transmission?

I'll check the SL forum again. Not sure what to use as a search. I tried before and came up with nothing. I think what you said about the torque limit makes the most sense. The car drives well and no check engine light. I'll have to be more careful on my launches in the future.

france2112

kchristos

Try to search the "Posts under YOUR name" !!
So...did you call Renntech to find out if they have an upgrade?

By the way, I live in Plantation too. I never had a chance to see an SL600 before, let alone a modded one! We (AMG owners) in South Florida should arrange some meetings to discuss and see each others cars (don't get me wrong, I know that my C43 is no match to your SL600). I am buying coffee at Starbucks some afternoon if you agree to take me for a ride with your beast!

https://mbworld.org/forums/showthrea...t=transmission

https://mbworld.org/forums/showthrea...t=transmission

HLG600

A few key points from your post allow me to agree with prsmith in regards to the transmission shutdown being a safety mechanism due to tremendous torque. You said the traction control was disengaged causing the wheels to break loose. Also, the RennTech modification amounts to an additional 155 tq. Next time try keeping the traction control on. I know it's hard because spinning tires is alot of fun .

prsmith777

MBTech21

Yes, it will shut down to protect itself, no, it doesn't hurt it, they would not have checked the trans fluid probably, as you have to break a cap off the dipstick tube and use a special tool to check it.

france2112

MBTech21,

Thanks for the tip. Makes me feel much better to know my transmission is not screwed up. I truly was worried. When I get a chance I'll have my transmission fluid checked. I really appreciate your expert advice. Take care.

france2112

MBrand

I recently purchased the ECU/TCU Renntech upgrade and had 4 shutdowns like you describe. All 4 were from a dead stop. We originally thought it was the trans going into safe mode. But I really beleive the car is redlining and shutting down once the RPM's go over 5800 (standard SL600 redline). Motorwerks, that installed the upgrade, wants me to shift manually for a week or so and ease into any sudden acclerations (what fun is that) to see if the problem will "work itself out". It may be that the fault settings need to be reset since the computer remembers that you redlined so it may do that every time you accelerate suddenly. I've also heard that the ECU may need to be flashed. I'm getting ready to call my contact at Renntech and see if I can add more intelligence. I don;t think it's the tranny getting too much torgue, the car is redlining!

AdamG@NorCal

How recent is this?

MBrand

I purchased the upgrade 9/21/07. Still waiting to hear from RennTech.

MBrand

I spoke to a RennTech engineer and MotorWerks has tested and solved the shutdown issue. I was completely wrong about it redlining. The new redline figure is 6300 from 5800 (although I did go over this once which may have been part of the source of the problem). The shutdown was a result of too much torque to the rear. A the tranny safe mode sends the car into neutral whereas a redline shuts gas down but the car will still be in gear. Apparently, the computer remembers faults and since I did have a transmission shutdown and maybe one redline, it stores this info and duplicates it. MotorWerks cleared these faults and tested a rocket ship! I have yet to test but will do so and advise.

MBrand

Aftter testing I once again put the car into safe mode...too much torque to the rear axle. Along with the RennTech upgrade, I also upgraded with the Quaiffe LSD. Does anyone have any thoughts as to why this happens or how to prevent it? I tested 0-60 this morning on my way to work keeping the ESP on and was disapointed to see 4.81sec! If I shut the ESP off, then I torque "out". Is there a acceleration technique I'm unaware of? It just seems silly to add so much power to a car if it can't handle it????