I have a vague memory that the engine computer will not allow more than 4,000 rpms unloaded...have any of you tested this? Does it apply to both the 6 speed and the automatic? Does this mean you can floor the accelerator all the way and drop the clutch without worry?

 

What it means is that without the front wheels turning, and no load on the engine, the computer will keep your engine from destroying itself by limiting it to 4,000 RPM.

As far as "dumping the clutch at 4,000 RPM"....well, if that's what floats your boat! Just be prepared to replace the clutch soon.

 

if you have the auto box, and move the leaver side ways to but it in the wannabe manual you can just floor it and it will changed gears by it self, so its just like putting the car in kind of sport mode with will just rev higher and still not give you any control over gears and shifting what so ever so i dont really get the point of bothering if they could do the same thing with a simple button.

 

is this limit only on auto's? i can rev to 6200 in my manual car at any given time, even spinning the tires.

 

As I go back & reread the original tests by C&D & R&T of the '04......(both tests were from 6-speeds)....the C&D article says the controls won't allow >4000 rpms unloaded ...whereas the R&T spec sheet (at the bottom) says "best launch by 4200 rpm drop clutch"......how did R&T get 4200 if computer doesn't allow >4000 rpm???????

 

My rev limitor kicks in about 4200 rpm..

But everythime I drop the clutch, it would bog the engine.. Am I doing something wrong when i drop the clutch?

 

^ It might dull the timing when you're bumping into the unloaded limiter. Try flooring it and dropping the clutch right before you actually bump the 4200 limiter.

But in all honesty, I don't think this car really has the torque to spin both huge rear tires out of the hole... yet. Probably do better slipping the clutch in from 4000 rpm. Just be ready to replace the clutch if you do it often.

 

i'm not sure if i would ever drop my clutch at those rpm. idk, i may have already. seems like a large hit on the drivetrain.

 

Drive train is covered for the lifetime of the car (2007) .. Unfortunately.. not the clutch though..

 

I don't think the clutch is strong enough to break a drivetrain part. Especially with all those rubber bushings.

When I sidestepped my Spirit R/T's Spec Stage 3 (2800psi 6 puck kevlar/ceramic) it locked. The motor banged on the solid rear mount popping the molding off the dash around the defroster vents and removing the faceplate from my Kenwood headunit.

The Crossfire's clutch just fights for grip and drags the motor down quickly.

 

its the traction control. Your better off launching at 3200 or so, and just letting the tires chirp, then punch it.

 

Traction control is another funny thing. Even when I turn it off.. it seems to still be on. I would launch, and heer a chirp and the traction control light would blink then the engine would bog.... even though its turned off with the light remianing on before I go.. Is this normal or am I needing to get it serviced..?

Thanks for any info.

 

^ That's normal.

It's never really off. Unless you find the fuse... but then you have the mother of all one leggers.

 

Thanks.. i was wondering why it would do that. i can now cancel my service schedule to have the TCS looked at.. Thought it was defective.. Now I have to hunt for the fuse..

BTW.. what is a one legger??

 

One wheel burnout.

With no mechanical limit slip in the open rear differential the power will take the easiest path (whichever wheel spins easier) and leave the car near motionless while burning off one of your tires.

It's usually not a problem if you can keep the weight even across both tires (like a launch on a flat level surface), but you're not always so lucky pulling out on street surfaces.

 

thanks for the info! Much appreciated... !
Sorry to the OP for hijack of this thread..

 

Its like that for all mercedes developed car..(mercs and our poor xf) YOU can never turn the esp in mercs completly off... notice the you, my father who used to have the old cl500 has a friend at mercedes service and there is a key/buttons combination that can be applied to turn it off completly. I had a go in my dads cl with it 100% off on a big empty parking lot and its nothing short of madness. He didnt tell us how to do it b/c he said it was in his contract not to reveal those kinds of things, but later we had a go with tc button-off and it was completly different.


On the other had i think its good that normal person cant turn it off 100% b/c its not like driving a bmw with tc off... the mercs with 300-600hp engines and 2 tons of mass would be imposible to control for ur average driver and it would be the same as comiting suacide