AlexMercedes

It seems like I have been having this issue of slow acceleration/response for quite a while now, but didn't think too much of it until recently when I lost to a car that is slower than a stock S600... I am getting not enough power in the high end as I feel like I should be getting, and the response of the car is really sluggish resulting in poor acceleration. Sometimes I even put my foot down all the way and the car does not feel like moving at all, it just stays in the current gear and accelerates very slowly with little boost.

I have had other issues regarding poor acceleration and responsiveness. I changed the MAP sensors, replaced throttle position sensor, and cleaned the throttle body, all resulting in fixing the issue I was having at the time, but there seems to be another acceleration problem that shows up as soon as I fix the previous problem.

I did some further research, and wanted to come here for some clarification. I've heard it is a common problem for the charge air cooler pump, or IC pump, goes bad in these cars often and causes sluggish acceleration and response due to the ECU getting bad IAT readings and tuning down the car's performance. Is this true? With my symptoms, is this the problem I am having, and will simply replacing the IC pump fix the issue?

oldsinner111

check vac leaks,fuel filter

Welwynnick

There are two standard things to check:
Make sure the IC system is full of coolant, and has no air in it.
Make sure the IC pump is working. They never last forever, and fail quickly when the IS system is empty.
These make a big difference, and there are lots of threads that discuss this.
Nick

tusabes

A good obd 2 code reader or the torque app on android phone should let you monitor iat.

AlexMercedes

I did change my vacuum lines and fuel filter in the past, so it can't be those. I'm sure it has something to do with the cooling system, because it definitely does feel faster when the car's operating temperature is still cold or when the air is cold outside. I'm looking at the IC pump now, as I am 99% sure that's the problem this time around. Is there any way to diagnose if it is working properly before replacing it so I can be 100% sure, or should I just buy a new one and pray it works?

Also my water pump did fail around a year ago and all the coolant got flushed out, so there was some time that it was running with no coolant at all. Could this also be a cause to the IC pump not working properly?

Welwynnick

You can test the pump by removing the IC pump relay and jumping the switched connections.

The pump relay is located in the middle of the small fuse board on the inside of the engine compartment partition. On UK cars it's next to the brake servo.
Open out a small paper clip and pinch the wire ends with pliers.
Remove the center relay.
Jump the pins at the front and the rear of the relay receptacle.
They're the opposing pair of connections that have blade pins at right angles to each other.
On my car the ignition doesn't need to be on to do this.
You should then hear the pump running.

Having said all that, the test only proves the pump is OK.

It's critically important to make sure there is no air in the IC system, and that's difficult to achieve.

The V8K IC shares coolant with the engine, but the V12 has a completely independent system, and it's full of air-locks.

Nick

tusabes

As stated the intercooler coolant circuit is completely separate from the cooling system circuit - two separate systems with separate fill caps- the intercooler fill cap is at the back of the engine .

dont just replace the pump , use a code scanner to read your intake air temp .

AlexMercedes

I'll start by checking if the pump is ok, then I'll flush the whole IC system as I'm pretty sure it hasn't been touched for a long time and there is most likely air in the system. Is the IC system supposed to use the same coolant as the engine? I used Pentosin Pentofrost NF for the engine coolant, should I use the same one for the IC system?

Also, what is the normal operating temperature you guys get? Mine goes up to 90-100 degrees Celsius depending on the weather or how I drive it. I feel like it should be way lower than that, as I seem to get the best performance around 80 degrees Celsius.

tusabes

A 95 Celsius thermostat is standard so if your car is getting to 95 it's normal . Over 100 is not normal

you can get an 80 Celsius thermostat

cybertronicify

Hows the power when the car is not heat soaked. IE, drive the car til engine tranny are at oper temp. Let it cool to 50C then start and floor it. (don't do it all the time, the engine is not at operating temp. Once is fine)

AlexMercedes

I've done exactly this and yes, the car is WAY faster. It is STUPID fast. I almost forgot I was driving a TT V12. Then when the car warmed up, it went back to being a slow piece of ****. This basically confirms that the IC system is bad

AlexMercedes

Ok, I've tested the pump and came to a conclusion that I need a new one. I've been looking around and doing some research on which pump to get. I know there are many types but which one would you guys recommend for the best performance and reliability? Should I get a new OE bosch pump, a reman OEM one, or are there any others that are better than those that I must get?

Also, when flushing the system, what coolant should I use? I used Pentosin pentofrost NF for the engine coolant and I have had no issues with it. Should I use the same fluid for the IC system, or is there a better one you guys would recommend? Thanks guys

oldsinner111

pierburg is the best,not bosch

Welwynnick

Bosch is OK.
Pierburg is better.
EMP is best.

Nobody uses the Bosch in new designs any more. Pierburg have pretty much taken over. But the advantage of the Bosch is that it's plug and play. All the mechanical, electrical and fluid interfaces are all there. you can upgrade a -002 to a -003 and to a -010. Modest gains. If in doubt, look for the pumps that have silver impeller housings, rather than black.

Nick

AlexMercedes

I'm assuming the pierburg requires modification. I also heard the Johnson CM30 is good. Is there any other pump that is better than bosch that is plug and play? If not, I'll just get the bosch one since it is still good from what I heard and there's no modification required. Is the 0-392-022-010 the most updated one?

Welwynnick

CM30 is the worst.
Bosch is OK.
Pierburg is better.
EMP is best.

Yes, Pierburg requires modification.

0-392-022-010 is the best Bosch.

AlexMercedes

I'm either going with bosch or EMP then. I'm also assuming the EMP requires modification. Is it worth the extra money and modification?

tusabes

Just get the Bosch since its plug and play

the original lasted 10+ years so will the replacement

AlexMercedes

I ordered the bosch pump. I will do a write up in case anyone is interested in following along, even though its been done before. I'll also be using Pentosin Pentofrost NF for the intercooler coolant, same as the engine.

One thing I am wondering though is if I did any damage to the system. I noticed that every time I floor it ever since I have had this problem, there has been this burnt smell right afterwards, presumably from the oil in the turbochargers getting too hot and burning away since they are always heat soaked. Could this have damaged something?

Welwynnick

Been there.

If the oil in the turbos burned, you would get smoke when the engine is idling, and the symptoms will get rapidly worse all the time.

Burnt oil clogs up the bearing chamber and in particular the hot end. Oil will then leak continuously out the turbine. There is no oil lip seal as such, just a small metal seal that looks like a piston ring.

Nick

AlexMercedes

Nick, thank you for that information, I was sort of relieved to hear that since I don't notice any smoke coming out the exhaust, only sometimes when its cold so I think I'm good for now. I'm having a hard time pinpointing where the smell is coming from, it only appears around medium to heavy load after 4k RPM and I notice the smell right afterwards when coming to a stop and idling. It goes away after a minute or two. I'm thinking it either has something to do with the IC system or it may just be from the catalytic converters. After I replace the IC pump and flush the system, I'll test it out again to see if the smell went away. If it didn't, I'm going to be looking at the cats next.

AlexMercedes

Ok I got the new pump today. I've been looking around on forums to find a well written procedure so I can do this job myself, but to my surprise I couldn't find any. How much coolant does the IC system use? What is the best way to refill the system and have no air bubbles? Should I install the pump before refill? Do I need to warm the car up before working on the system? Hoping someone can chime in and help me, and I'll do a good write up in return for the forums. Thanks

henk92

Super easy to change the pump. No need to warm up anything. Just change it. Fill it up after you are done. you can go the vacume bleeding benz route or put an extra overflow reservoir in it to keep the ic system full at all times.

Going back about how to test an ic pump. I not understand why all the jumping relays and things are done. I just put it on my xentry and i can see in the computer if pump is running or not.

tusabes

Here is how to install the overflow
https://mbworld.org/forums/m275-v12-bi-turbo-platform/562924-intercooler-circuit-overflow-reservoir-2.html

AlexMercedes

I installed the pump today. Wasn't too big of a difference much to my disappointment. It was pretty hot outside today ~85 degrees so I hope that is the reason. The intercoolers were still burning hot after some hard driving, but I did feel a SLIGHT difference on WOT. I am thinking I either have too much air in the system, it is just too hot outside right now, or one of my MAP/boost sensors went bad. I only replaced the two MAP sensors that are connected to the sides of the airbox, but not the one that is directly above the throttle body or the one below the voltage transformer. What do you guys think should be my next step