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M275 V12 Bi-Turbo Platform Technical discussion relating to models sharing the M275 V12 Bi-Turbo (V12 TT). Including SL600, SL65 AMG, CL600, CL65 AMG, S600, S65 AMG.
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No more than 15psi of boost :(

 
Old 03-24-2017, 06:25 AM
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2013 W204 C63 AMG, 2008 W221 S65 AMG
No more than 15psi of boost :(

Hi all

Recently replaced my front IC radiator as it had a leak. All bleed and working properly. My IAT's are looking much better now.

Unfortunately, I am still only making 15psi of boost.

It should be closer to 21 on this car.

A graph of IAT VS boost pressure is below:


IAT in Deg C and PSi on left, RPM on bottom.

Numbers:

RPM IAT PSI
2425 43 0.43511391
2682 43 0.43511391
2682 43 0.43511391
2682 43 10.4427166
3212 43 10.4427166
3212 39 10.4427166
3757 39 13.77858543
3967 39 13.34347153
4104 39 15.22896194
4395 39 13.48851013
4551 39 15.22896194
4701 36 15.80911446


I have new clamps everywhere, including the beefy larger T clamps from the Turbo outlet to the IC inlets:



Am I right in thinking that the wastegates are closed by default, and then are held closed with the boost control solenoid? If there is a vac leak from this solenoid or its not working, what is the default wastegate pressure?


Any idea where to look next?

Last edited by alexanderfoti; 03-24-2017 at 07:15 AM.
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Old 03-24-2017, 09:26 AM
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If I clamp the boost line that comes from the Intercooler, I saw 18psi once, then it went into limp mode. Erased the codes and then only saw 10psi.

I removed the clamp and back to 15...... Wonder what that means? Thinking about it, I wonder if the ECU pulled open the divert valves to bleed the boost.

Last edited by alexanderfoti; 03-24-2017 at 10:22 AM.
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Old 03-24-2017, 12:12 PM
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2013 W204 C63 AMG, 2008 W221 S65 AMG
Got Xentry on it, was an over boost code, so the turbos are making OK pressure and there aren't any boost leaks.

Additionally, the pipework to and from both the Divert actuator and the boost solenoid seem to be intact with no breaks. This must also rule out weak diverter valves.

All 4 MAP sensors are the correct ones and in the right place too. Air filters are new.

Off for a dyno on Tuesday with boost tied in as well so will be interesting to see if its 15psi is by design or if its low (I think its low)

Last edited by alexanderfoti; 03-24-2017 at 02:45 PM.
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Old 03-24-2017, 05:33 PM
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2003 CL 600
Your info says CL55, but this is the v12 forum, which model do you have? The 600, that boost is actually a little high for stock. for a 65, it's low.
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Old 03-24-2017, 05:35 PM
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Originally Posted by ItalianJoe1 View Post
Your info says CL55, but this is the v12 forum, which model do you have? The 600, that boost is actually a little high for stock. for a 65, it's low.
Sorry, Just updated it, I have both. This post is about a 221 65 AMG.
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Old 03-24-2017, 05:37 PM
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For a 65 car you should see over 20psi at times, the fact that it slowly builds as rpms climb makes me think you have a wastegate not closing. You should have full boost at 3k, and it tapers off with rpms as the turbos simply can't keep up with the airflow demands.
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Old 03-24-2017, 05:41 PM
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2013 W204 C63 AMG, 2008 W221 S65 AMG
Originally Posted by ItalianJoe1 View Post
For a 65 car you should see over 20psi at times, the fact that it slowly builds as rpms climb makes me think you have a wastegate not closing. You should have full boost at 3k, and it tapers off with rpms as the turbos simply can't keep up with the airflow demands.
I feel like its being told to to do that by the boost control valve. Pinching the line to the boost pressure control solenoid keeps the wastegates shut, which should make max boost all the time (or at least wastegate spring pressure, which I cant find). It seems to do that under testing.

Last edited by alexanderfoti; 03-24-2017 at 05:44 PM.
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Old 03-28-2017, 08:05 AM
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For sake of completeness, numbers are in:

Seems spot on to me. peak boost measured at 20.3 psi

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Old 03-31-2017, 05:45 PM
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where in DAS can I check pressure please ?
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Old 03-31-2017, 05:47 PM
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Actual values. Engine under full load.

Needs 2 people though, need to drive full throttle whilst watching screen.

Much easier to data log whilst on dyno.
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Old 03-31-2017, 05:53 PM
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Originally Posted by alexanderfoti View Post
Actual values. Engine under full load.

Needs 2 people though, need to drive full throttle whilst watching screen.

Much easier to data log whilst on dyno.
thx
yep dyno is easier
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Old 04-13-2017, 12:04 PM
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2005 S55 AMG
So on my S65 I am experiencing the same thing. During data-logging I am only seeing 1960-1980 hPa. I have no boost leaks and replaced the boost control solenoid ( under driver intercooler) I am starting to thinking the data logging method isn't giving me the correct results( i am using a icarsoft i980 for data logging.) Where were you getting the reading of 15psi from? and then when you went to the dyne the car was make 20+?
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Old 04-13-2017, 04:02 PM
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Originally Posted by g60wall View Post
So on my S65 I am experiencing the same thing. During data-logging I am only seeing 1960-1980 hPa. I have no boost leaks and replaced the boost control solenoid ( under driver intercooler) I am starting to thinking the data logging method isn't giving me the correct results( i am using a icarsoft i980 for data logging.) Where were you getting the reading of 15psi from? and then when you went to the dyne the car was make 20+?
The data logging was done via OBD with Torque and also via the dyno operator. Both via OBD. I have not verified the actual boost pressure being produced with a meter connected directly to the system.

If you check the dyno graph, the purple line is boost pressure. It immediately makes 15psi, then flattens out until 4000 odd rpm, where it then spikes to 21 randomly then drops back down again. Its only consistency was the 15psi early on.

It did not make a reliable 21psi on dyno and I disagree with the "calculated" crank hp numbers on that sheet.
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Old 05-11-2017, 12:05 PM
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For the sake of completeness, I have carried out the following, see this post
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Old 01-11-2018, 03:21 PM
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An update for all:

The problem is fixed. There were a few things at play,

First, when I bought the car, the IC radiator at the front had a leak and the IAT's where through the roof, I though this was the cause so fixed that, no change.
Then I thought boost leak, engine knock, wastegate issue, bla bla bla. I could not get more than 17 psi. Car dynoed 440 WHP and 800 NM WTQ

Halfway through I involved a local tuner/racecar builder that is very good (by reputation) but he obviously could not have cared less and was just a pain in the **** the whole way through. Whilst the car was at his I got him to put a quantum ECU tune on it to see if that would change the boost levels but it did not. This was a big mistake as it added another level of complexity.

With the help of g60wall (thanks!!) and some data logging, I deduced that the torque converter slip ratio was too high, and THAT was the reason that the ECU was pulling timing and boost.

I replaced the torque converter, the TC lockup solenoid (which solved my cold harsh TC engagement) and also had the valve body rebuilt and had a sonnax kit put on the TC bore. The gearbox is now sweet and drives around much nicer than before.

I was initially disappointed as the car didn't make much more boost, 19psi compared to 17psi before. I then put it on the dyno and it did 510 WHP and 860 NM WTQ

It was then clear what the quantum tune had did, I got copies of the tables that had been changed. 6 Degress of timing advance and they had obviously neglected to increase the global torque limiter and so the car was making more power with ignition timing and less boost.

I put a eurocharged map on it and 23psi boost that holds 21psi to 5000rpm!! Only issue now is that all my plugs on one side misfire above 5000rpm so cannot dyno, but the car feels significantly faster. New packs are on there way and I hope that's the end of it now!

Thanks for the assistance everyone! Especially G60wall!!

Last edited by alexanderfoti; 01-12-2018 at 04:11 AM.
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