Reduced IAT's - Pump rewiring Results
 

We had few threads lately talking about rewiring the intercooler pump to run all the time, however not many showed real world results/comparison to stock.
My car is not stock, however cruising/regular driving Intake Air Temperature (IAT's) shouldn't be off by much regardless of which tune you're running on the same car.

I cant thank @brutus_tx enough for his help, been wanting to do this for a while and his post just encouraged me and showed me how easy this was. It literally took me 10-15 minutes to do this, and now it can be done in probably 5 minutes.
Scrolling down to post# 24 of this thread https://mbworld.org/forums/w212-amg/...rket-mods.html @brutus_tx shows how he rewired his, while this looks super simple I'm sure it took a lot of time to research it, and not to mention having the guts to be the first one to ground a wire out of a harness, I'd be worried which fuse is gonna blow the second I start it lol

For those who dont know, our stock intercooler pump is always off, it turns on when IAT's reach 43°C=109.4°F (ish, give or take). This hurts a lot when driving the car aggressively or doing one pull after another. By the time the intercooler pump kicks in and cycles the water back into the core your race/pull is done and you suffered a decent decrease in performance due to hotter air. IAT's are MUCH worse than stock when tuned, specially stage 2.
On my personal car with a stage 2 tune, colder plugs gapped at 0.022, high flow filters, intake spacers, 94 octane after few pulls I was seeing IATs as high as 65-70°C=150-160°F when I'm at full boost. Yesterday was 15°C=60°F outside, driving around I was hitting IAT's of 19-22°C=66-72°F. Driving it hard and pull after another, I didnt see much over 38°C=100°F.

I didn't do a full datalog yet, however I can see MASSIVE drop in my IAT's while cruising and hard driving, I will log tonight to see the difference between stock configuration vs running all the time in a 4th gear pull.

You wanna tap and ground the Brown/Blue wire going into the relay below, this works on Facelift cars only, pre facelift dont have this relay, its most likely hidden somewhere else.
https://cimg4.ibsrv.net/gimg/www.mbw...0ce0681617.jpg

I did things slightly different than @brutus_tx, I pulled the yellow insulator out and inserted the wire into the relay, this way I dont have to cut into the stock harness and things look stock-ish if I need to visit the dealer.

https://cimg5.ibsrv.net/gimg/www.mbw...cb4edde27d.jpg

Run the wire to the grounding point right next to the relay (picture below thanks to @brutus_tx again)
https://cimg5.ibsrv.net/gimg/www.mbw...82de60d290.jpg

You need a wire thats like 4-5" long, add a ring terminal at one end and a bit of solder on the other end. Adding a bit of solder helps while squeezing the wire into the yellow insulator after taking it out, dont try inserting it while its in, its super tight.

https://cimg6.ibsrv.net/gimg/www.mbw...b74b25f5f6.jpg

This was last night, I never did see 45°C=113°F (which what shows under highest value). However when the car starts its at 45°C=113°F and start dropping down quickly. I noticed IATs are usually ~10°C/18°F over ambient.
IATs are alot higher when idling, the minute the car starts moving and air flows into the heat exchanger you can see notice the drop. I will post a video later on tonight.
https://cimg6.ibsrv.net/gimg/www.mbw...5c49a99b6b.jpg
https://cimg3.ibsrv.net/gimg/www.mbw...e9d55c30ff.jpg

Glad I could help. My inspiration came from Dave at EC ATX. He's the one with the knowledge... I'm just the scribe.

Excellent write up by the way.

I'm a fan of easy mods that don't cost a ton of money that show real world tangible results. There aren't a lot when it comes to AMG, but this is one of them.

Those are fantastic results. What are you using for fluid? Coolant or distilled water and water wetter?

This mod costs practically zero but have a great impact on performance.

I see you have the Uniden R7. I'm a fan of that radar detector as well.

Nice work!
This is always been an issue with the M157 no matter what aftermarket big h/e you may have, if the pump is not circulating the coolant, it is not being moved and cooled, pump operation plays a major role.
Mercedes likes to target a very high IAT for their own internal reasons, but for us its bad performance.
The h/e pump likes to kick on around 113F IAT and turn back off when temps reach 104F.
Another issue with this is, the delay in time of coolant track flow. From the time the pumps turns on and is able to move the fluid throughout the system to be cooled. That delay of course leaves performance on the table. With the pump running prior, this helps get a big headstart.
Many advantages to us for performance; negative side, shorter pump life which most of us are willing to sacrifice i am sure :)

Attached are before and after runs, files are the bottom of this post.
Its crazy what a difference this thing made on very similar runs.
Both runs are back to back.
No pump mod:
First run starts at 38°C=100°F at 3K RPM and tops at 65°C=149°F at 6K RPM
Second run starts at 32°C=90°F at 3K RPM and tops at 74°C=165°F at 6K RPM

With pump mod:
First run starts at 14°C=57°F at 3K RPM and tops at 29°C=84°F at 6K RPM
Second run starts at 23°C=73°F at 3K RPM and tops at 39°C=102°F at 6K RPM

Very close to half temp drop between the two!
I'll do few more runs later on tonight.


This run was when I first started, was driving the car for 15-20 minutes before I did my run, outside temp was 8°C=48°F
https://cimg9.ibsrv.net/gimg/www.mbw...f01a2e556b.jpg

This was after the runs, I did a total of 10 runs (didnt datalog all runs) but this was after beating on it for a while.
https://cimg5.ibsrv.net/gimg/www.mbw...9af38aac82.jpg

Why not just change the set point for the pump to a lower coolant temp? Set it for 60f and call it a day? At least this keeps the pump off at startup and saves some life expectancy? Not programmable?

From what I read/was told lowest you can set it to is 90 or 95

I did it Friday. Works perfectly!

Anyone know where the pre-facelift relay would be, if it has one?

Pre facelift does not have a split cooling system .

ok...still has to have a relay...lol


I haven't been able to find mine on my pre-facelift, but I was told that STAR shows it in the passenger footwell...still looking...

My pre-facelift E63 w/ P30 runs split cooling from factory. There is no relay next to the main expansion tank. Must be somewhere else. I was unable to find in WIS, but this is called "low-temperature water circuit."

I believe it was added to MY2013 AMG's and MY2014 for E550.

Curious what this does to the lifespan of the pump - I dont have any mods at the moment but this is an interesting cheap way to get some added benefits of lower temps.

"If all is configured correctly, the simple act of opening the car door with cause the pump to turn on and start circulating coolant. This will be evident by noticing flow in the IC reservoir."

I'd probably put some kind of a switch on the short circuit or something to make storage and work on the car less of a surprise.

If I was ever in the engine bay and then someone opened the door that'd be a shock to have the pump turn on.

It may in fact shorten the lifespan, but we have had it like this in our shop for for over two years without any issue, runs perfectly, no problems - for what that's worth :)

Thanks!

Dave

Not true, my friend with a 2012 E63 P31 package came with stock split cooling. However, no relay.

Anyone know where this might be on a MY2013 CLS63? Would love to do this easy mod!

With this mod, is the Relay trying to be grounded at all times or the wire that's being tapped off hand? I'm sure I can test it, just want to know before I tackle it.

Would like to do a cleaner install -- ie. depinning the relay holder, insert new wire, ground it.

I actually ran a 5 amp fuse between the relay and the ground. This way if you want to go back to stock setting just pull the fuse.

Did anyone find out where the relay is for the pre facelift car? Mine is a late 2012 with the slit cooling system.

Many thanks!!

Trev.

This is awesome thanks! I just did it and you can def tell a difference. Here is a little video on it:

Just an FYI: Hardwiring I/C pump is no longer necessary
 

I never found mine, but EC has figured out how to turn it on in the tune now, so I have my tune re-written to include the I/C pump on all the time. Even better as I didn't have to hack up the wiring...

I asked about that, but I heard only to a certain lower temperature. Are you sure it always on?

My cls is prefacelift. I've also seen this relay near the fuse box and I believe I read someone said it could be in the trunk electronics area or right rear too for some reason? I would check fuse box tho I've seen a few pictures of them there, and they had to be like moved a bit.

Personally I don't know if split cooling is tied to model years. It might be but I think there are optionally configured engines earlier with split cooling, even w/278. Not sure.

yes, I'm sure. I've monitored IATs and they are consistently low with no signs of the pump turning off(Stock: temp ramping up to signal temp, then cooling down when pump comes on...)

I'm a prefacelift w212, but mine does not have a split system. could have been an option(???) but general consensus is it was added mid-2012 on the 212 body, not sure on CLS.
WIS shows relay in passenger footwell, but I don't have one there.

I could not find the damn relay yet either. Not in the footwell.

How did you pull our the yellow insulator to put the groud wire in?