how do i konw it worked? any indicators w/o driving?

 

Nope. Unless you drive like a crazy person all the time, it will feel peppier when you acclerate. If you are trapped in commuter traffic most of the time you will notice the difference. Until you get in traffic again.

 

I drove the wifes Clk500 for a couple of days while she drove one of the other rides and today she jumped in the CLK500 and said, "what kinda gas did put in it, why does it seem faster?"

 

Just did this today and figured this thread deserved a bump for people who didn't know about it. I was slightly hesitant to try it but all the good feedback by my w209 brethren had me go for it.

Significant difference noticed asap! I do a lot of traffic commuting so my ECU was set to grandma mode, but now its great!

 

Also have to tell after exhaust install, something seemed not acting right in my car, so adding up grandma mode + unadjusted fuel/airtrim as same as the irregular shiftpattern in grandma mode it was no secret I had to do something.
Kevwood suggested to do the ECU reset...what can I say, shes back, shes well and alive. Loosing the rear by tapping on the gaspedal a little faster, really have to get used to it again.
As for sideeffects like mirror is not working, havent discovered any malfunctions.
ECU RESET, all day baby....all day :-D

 

Just to confirm this works great! Mines a CLK 200K C209 2003. Feels much more responsive - and much less fuel efficient!

 

Just give it time. It will re-learn your grandmotherly driving habits and you'll be back in the slow lane! Seriously, it will relearn driving habits, and if that is in heavy traffic without much opportunity for some throttle play, then it will go back into "easy-shifting" mode. I try to make at least two hard, full-throttle accelerations per drive just to keep mine from going granny.