rondocap

I would really like to know exactly what is happening in terms of the power delivery/timing of the NA 55 engines in the older cars. (Like the W210 E55, W220 NA S55, etc)

Here's what I am talking about. I have an S55, and for all I can tell it is very healthy and typically runs very strong.

If I accelerate fully, with the kick down, up to about 30mph and below, I get a really strong push back in the seat, and the car's engine seems to go into an "overdrive" mode and really take off. The strongest range seems to be about 5mph-29mph or so to feel this after the car is already moving. How can this be explained? Is it the pulley engaging? Or what?

Similarly, If I accelerate from starting from around 31mph, and even if I start at around 50mph, the car does not seem to go into that "overdrive" mode. It still accelerates quickly, but it's much smoother and I do not get that push back into the seat. What explains this?

And lastly, starting at around 54mph, and each speed up to 65mph, it happens again - I get that really strong push back into my seat and the car's pulley seems to engage or something like that, the noise is louder and more aggressive - similar to the 30mph pull but at a higher speed. If I kick down 66mph or higher, it does what it did 31mph-53mph or so - still accelerates rapidly but I don't get that "kick" and it is much smoother.

I hope you guys can shine some light on this - is it the pulley engaging, or perhaps the power band, something. I know that you can't expect the same power in every speed/RPM, so I am curious exactly what is going on here.

desired_speeds

There is no pulley engaging, its simply the kick down switch at the bottom of the gas pedal that throws it into the lowest possible gear when you floor it and hit the button. when you say it accelerates quick but not as fast, its probably because its not in the correct power band and it doesn't pull as hard. Sometimes the auto trans also makes it bog for a second when you floor it from certain speeds.

tsquare

I do not know this for a fact, but the way you describe the kickdown of the transmission at the speeds you have described makes a great deal of sense from a driveability standpoint.

Having the greatest acceleration in the 5 mph to 29 mph range for startoff and street driving and then for getting on the Fwy / Hwy having again the greatest amount of acceleration from 55 mph to 65 mph would also make the most sense. I am certain they (AMG engineers) programmed these parameters for those specific purposes. When you are in other speed ranges - strong acceleration is still important, but maybe not as important as the two specific ranges you have described - just an idea - makes sense to me.

One thing I have noticed on my E55, the car has two distinct personalities. If I drive the car with an easy on the gas pedal manner, the car behaves in sound, acceleration and gas mileage as any normal luxury sedan. If I drive the car with a heavy foot on the gas pedal, the car becomes loud (great sound coming from the valvetrain), very aggressive in accelaration and of course much more fuel hungry. The balance the AMG engineers have created on these cars is quite amazing.

Schweinhund

You do reset the ECU every two weeks?

MBFLO

damn for real^^

need to get mine done

sly55

I agree it simply sounds like the kickdown into a low gear giving you what you describe as "overdrive effect".

Either way mercs arent exactly known for their sharp throttle response even in AMGs (although i havent driven the latest offerings) if you want to really move you have to plant it to the floor.

Also the transmission ratios arent the best for giving you that "on power feeling" all the time.. 1st and second will feel like a rockets up your pants, anything from third on is a bit dull in my opinion due to the length and spacing of the gears.