I'm new to my CLS 55 AMG. Got it in January, but since I live near Detroit, I didn't really start driving it till April. Not going to drive her on our salty roads. On the first 80 degree day we had up here, I noticed I had no power when I dropped the hammer to get thru a yellow light. That's when I found out about heat soak. Something new to me. From searching this forum, I suspected the IC pump. I already had a bluetooth OBD reader. I got the Torque app, and it confirmed my IAT was way high. I was running 20 to 30 degrees over coolant temp. Like 150 to 175 degrees. I got a new Bosch 010 pump and installed it today. It was very easy to do. I am now running 20 to 30 degrees over the outside air temp and, with my new exhaust cut outs, it feels like a different car. My 8 year old said; "Dad, this car is a beast !" I was like, "yes it sure is !". I'm not going to do any "go fast" mods. Maybe a belt wrap kit. I think AMG knows what the limits are and set the car up so as to not over tax the engine. It's plenty fast for me as Is. I swear the exhaust cut outs gave her a bit more punch. I did that before swapping out the IC pump. With the new pump, wow, this car is quicker than any Detroit muscle car I ever had. I notice the trans seems to hunt a bit. More specific, it is "long" to shift. On most every auto trans car, I can make the trans shift by backing off the gas pedal and getting back on the gas pedal quickly. Not in this car. If I back off the gas it doesn't up shift, it still wants to go for the higher gear. It shifts better in manual mode but, not as quick as I would like it to. I have had the trans serviced {fluid and filter replaced}. I also noticed that when I stomp it, it wants to go almost to red line before it shifts. I find my self backing off the throttle because I'm afraid Im going to scramble the motor if I don't back off. Is this normal ? Any one know what I'm talking about ? Any input would be greatly appreciated. I've always been a BMW guy, but this Merc is way better than any beemer I've ever had and I've had serveral of them. So glad I have this forum to educate myself on this car. Thanks for checking out my post. Rick in Detroit.

Omg someone who wants to understand his car! Ok let's get to it. The cls55 AMG 5 speed transmission is pretty much bulletproof unlike the 7 speed found in the CLS 500 and 550. There are a few weak points however. The connector will leak on the passenger side of the unit and cause the fluid to wick up and if there is any metallic particles in it then it's going to scramble the tcu so check it out. There are two rubber o rings and it's generally the larger one that leaks. The second weak point is the conductor plate that sits on top of the valve body. It's prone to failure because it is made of plastic and extremes in temp will cause it to distort. That coupled with the solenoids (6) that are attached to it and the exposure to fluid with or without metallic particles will cause ( not may cause) erratic operation like not finding a gear or hesitation shifting out. If you need to shut it down and restart to get it to reset get ready to change the conductor plate BEFORE it sets the code in the tcu because if it does the trans will go into limp mode and you won't get it out of 2nd gear. The shifting from park to any drive gear will be harsh and jarring. Then you will need a high end scanner or Star to clear the code. Change the fluid and filter religiously and be alert for any telltale signs of "pending failure" that starts as unusual shifting patterns. Then there is the plastic pan that also warps and starts to leak. I replaced mine with the metal one and solved that problem.
As for your specific questions this trans won't shift when you get off the gas. It goes right to redline and shifts. Once you punch it the Ecu and tcu declare war and go to redline. In the event the trans would for whatever reason not shift the rpm limiter would shut the engine down and keep it from exceeding redline. You just need to get used to what you have. With all due respect to bmw this is NOT a Bimmer not even an M series. It is unique both in performance and handling. You have a beauty enjoy it. Good luck.

Thanks so much for responding to my post. I just replaced trans fluid, filter. I will check that connector and o rings. Thanks again.

Your transmission is normal and it will learn how you drive. Look up sneaky reset. Also there are tuners on the E55 forum that can change the programing.

So, before you changed the pump were you not getting any messages on the dash about limiting power due to high temps (or something to this effect)?

No messages from the car. Only way I knew something was wrong was because when I nailed the gas, let's just say; "the thrill is gone". I researched, and became familiar with the term : "Heat soak". I noticed it when the weather got hot. I replaced the pump. I bench tested the old pump. Ran direct {12volt) to the pump and it was dead. Before replacing the pump, I checked out the Intake Air temp with my blue tooth OBD hardware and smart phone app. I found my IAT running 20 to 30 degrees over coolant temp. Forum posts said IAT should be 20 to 30 degrees over AMBIENT. Super charger hits every time I nail the gas after replacing the pump. Very easy fix. Did it on the street in front of my house in 30min. Line clamps are a must to perform the fix. The blue tooth OBD reader and torque pro app are totally worth the $30 investment for our cars. If you are able to do basic repairs on a car, this tool, and this forum, will save you a s#*t ton of money. Working on our cars {DIY} is no different than working on any other car. They may seem intimidating, and you don't want to "F" something up, but if you can fix your daily driver at home; you can fix your AMG too. Just do the research and take your time. It is a really rewarding feeling when you figure out what is wrong and take great care fixing it, then boom, "Hey it worked, I did it". The only thing that holds me back from working on my car is not having a hoist to get underneath it. I'm talking about routine repairs, not major engine/trans issues.

Can you tell me where I can find the "blue tooth OBD hardware" and what the app is for your smart phone?

Also, thanks for the great words of advice and encouragement. I have found this forum very valuable for years. It is people like you that make it great. Cheers!

My IAT hit over 165 degrees F when hammering it. It quickly fell to 118 degrees F when I let off the throttle. The ambient temperature was 85 degrees F. What are your thoughts?

Your pump and cooling system is working fine. If you want to go cooler you can always upgrade the heat exchanger and even the stock pump. More over, splitting the cooling system between the supercharger circuit and the engine circuit will be the next step. I have recently done this and I think the volume of coolant on the supercharger side needs to be increased since my temps fluctuate quickly according to the IAT readings on dash-command app

One of the largest considerations about a failing IC pump is the 3-12 degrees of engine retarding for ignition timing as IAT increases. As the temperature of the IAT increases, the DME automatically starts to retard the timing of the engine to prevent knocking. That means that even if your IAT temperatures are low, if they aren't coming down as fast as they should be because your pump is marginal, the DME could still be dropping performance because it's compensating for a failing pump and rising temperatures by retarding the timing of the motor, and thereby generating less heat.

I looked this up recently on WIS because my IC pump is failing, and my IAT is hitting 165-170. I'm not usually hard on my car, so I haven't received any error messages at all in STAR, but what is interesting is the ignition timing readings coming off the DME because of it.

Something everyone should check. In my case I hooked up my STAR and watched the IAT temperatures on the laptop while someone else was driving.

Thanks for this thorough description.