vdubpower

Our 2015 S550 has a cel that is p02990 which is a low boost pressure noted. The car seems to drive fine in terms of power from what I can tell. The shop I took it to produce this video. And noted that the wastegate actuator was bad. I wanted to get the forms opinion on the situation and what options I may have. The car is stock and has 145,000 miles on there for the regular services
https://youtu.be/oHGPX-WGf-4

BDC90

I would think the test would involve a vacuum pump on the actuator to make sure it holds vacuum not just looking at it at idle speed.

vdubpower

i Will check with the shop....thanks

i hope im not looking at a new turbo

PeterUbers

https://mbworld.org/forums/w212-amg/...ck-engine.html

https://mbworld.org/forums/w212-amg/...ease-help.html

vdubpower

Thanks. Shop has said basically engine out new turbo. But I'll ask about the wastegate actuator rod clip.

New turbos are not in the budget. That's for sure

BDC90

I am not an expert with the M157 but most turbos I have worked on the actuator is a separate and replaceable part. If the rod end is worn the wastegate may not close completely allowing boost to bleed into the exhaust prematurely.

Chevota

Apparently the wastegate hinge wears and makes it sloppy, then at some point the gate no longer closes properly. Maybe binds, no longer sits flat or whatever. Yes you can fix it but a lotta time and work considering the turbo is near death anyway.
If it were me I'd check the vacuum because the when the little check valve fails, and it will, you get low boost. So will leaky vac lines, or oil in the lines that fill the vac cans. If all checks out I'd bypass the turbo solenoid, feeding the turbos full vacuum and see if it makes boost. Be wary because it can easily overboost, specifically between 2 and 4krpm. So I'd take it to 4k locked in gear, then floor it. But my #1 suspect is the vac check valve on the vac pump. Its behind the left (port) head. Just follow the vac line from the turbos. The check valve assy is easy to remove, one screw.

C43 Fun Haver

Just recently had some vacuum issues which was giving me code P023409 boost pressure too high on turbo 1.. so this is what I did
values were 5% actually target 65-97%
after replacing the vacuum pump and pressure solenoid (Y77/1)
values restored to 74%. targeted was 65-97%

Blow out the vacuum line from the pressure transducer to the vacuum pump, mine was filled with oil. There was no oil in the vacuum lines from the transducer to the turbos, so the transducer was stopping any oil continuing down.

Verified the turbo actuator rods still move, brake boosted and just visually watch them move..
Someone else mentioned the clip for the turbo actuators, verify those are still there.


i've got a 2015 ML63, stage 1 eurocharged, 92k miles. about 7k new miles since tuned

ScottyP1

Thank you for posting this. You saved me so much time and trouble.