jclaus98

Hello gents, longtime member of the group, previous m156 owner, new to the ML63 AMG, m157 platform, having issues building boost. As noted, this is an ML63 AMG with an m157, P30 performance package, 2012 MY. My butt dyno had a hunch something wasn’t right, so I ordered up an AutoMeter dash link and it confirmed what the butt dyno feared - the m157 is only building about 13 psi at WOT. No codes present. I’ve had some experience with boots issues in the past; my brother has a Nissan Frontier with the supercharged V6, and it would randomly cut boost as the knock sensor began to fail. There were no codes present, but a gauge confirmed that the computer was limiting the boost to 2 psi when the max boost at WOT was supposed to be around 5 psi. Has anyone else experienced anything similar with their m157??? If so, what was the root cause? Any assistance would be greatly appreciated.

jclaus98

Anybody?

Roverron

try the W212 sections more guys tuning their cars and more help.

jclaus98

Thank you! Much appreciated! I'll try that.

RWDragoon

I've tuned my ML... fuel quality is everything. It will naturally detune itself with low quality fuel.

jclaus98

Agreed. My concern is how badly it may be detuning itself and if there’s a larger issue than just fuel quality. With it only building 13 psi, if the stock boost with the PP is supposed to be 14/15 psi, then I can see fuel quality, maybe even elevation, being the culprit. If it’s supposed to be building 18 psi, then I fear there could be something else wrong. Potentially a boost leak. I’m trying to get a definitive answer from someone who can confirm exactly how much boost it’s supposed to be making.

jclaus98

FYI - For those interested, I reached out to Weistec about this, looking for information before I spend $2k on a tune that may be ineffective if I had an underlying mechanical issue that was limiting boost. Per Weistec, 13.2 psi for my elevation (~5550ft) is nominal. Sea level vehicles will see nominal boost of 15-16 psi with peaks of near 19 psi. Per Weistec, if there were an issue reaching the target boost level, the ECU would log a P0299 code for "turbocharger underboost" and limit boost further to protect itself. Hope this helps anyone looking for info like I was.

daisyfresh

This is great info, thanks!

cunningstunts

Did you end up getting a tune for it? Can't help but feel a Weistec, eurocharged or similar would meet better results than pp package.

DavidLN

Hello:
It appears they are telling you that the turbo controller is not altitude compensated? That seems unusual to me. At 5500' elevation you lose just under 2.5psi of atmospheric pressure. With the P30 package you should make 18.2psi above atmospheric. Using their reasoning (18.2-2.5=15.7psi) the numbers are still way off. Page 22 of Introduction of the New Generation of V-Engines 8-cylinder M 157 AMG, states "In this way the boost pressure of max. 1.0 bar
(1.3 bar in engines with Performance Package) relative to the environment..." Relative to the environment indicates this is an altitude compensating system. You should make the 18psi of relative boost above ambient conditions. That would be 18 + 2.5 (5500' altitude). The gauge is referenced to atmospheric pressure. Your absolute manifold pressure will of course be much higher.

Dave

DavidLN

Greetings:

I have an update gained from recent service at the MB dealer. I have a mechanic at the dealer that I trust completely. I was experiencing the "low boost" that has been mentioned earlier. He said that these vehicles on;y make about 0.9bar/900mb. I shared the info I read in the above-referenced MB publication. He researched it and found that the factory diagnostics show the 900mb id normal based on my VIN. I have a 2014 with the P30. It would appear that there is a large misconception regarding the boost pressure of the P30 equipped vehicles. I also noticed that the date of the M157 publication was 2010. He pointed out that low boost would have triggered an indicator light.

I'm still reading and researching.

Dave