Losing Power, losing boost at high RPMs
Need help as I’m stuck. Car runs good not rough, only 25k miles. Had stage 2 for 4 years now, normal drive, I don’t drive it to hard, maybe 20 pulls to 100 mph since I own this car.
One day I notice my car seems slow like slower than my Stock Lexus RCF. Saw boost dropping back down to 1/4 after 4-5krpms. HP reads 330.
Bought smoke tester and found no leaks whatsoever, none in the exhaust. Then notice smoke coming out of the two hoses under the intake, I believe it to be PCV hose line. Is this a bad sign. Can a bad PCV cause my car to loose boost.
any help is much appreciated.
thanks


Need help as I’m stuck. Car runs good not rough, only 25k miles. Had stage 2 for 4 years now, normal drive, I don’t drive it to hard, maybe 20 pulls to 100 mph since I own this car.
One day I notice my car seems slow like slower than my Stock Lexus RCF. Saw boost dropping back down to 1/4 after 4-5krpms. HP reads 330.
Bought smoke tester and found no leaks whatsoever, none in the exhaust. Then notice smoke coming out of the two hoses under the intake, I believe it to be PCV hose line. Is this a bad sign. Can a bad PCV cause my car to loose boost.
any help is much appreciated.
thanks


Also, with the car off, I'm not sure if the PCV solenoid down at the throttle bodies / intake runner area remains open or closed. If it remains open then my theory isn't as solid, because you are just pushing smoke through the turbo, into the intercooler, and intake runner, and then back up through the PCV system (if it stays open with the car off) to where the turbo inlet is. Hopefully a MB tech, or somebody certified can weigh in, or if you have Xentry perhaps you can manually toggle open and closed any PCV solenoids to see if that makes a difference.
will the PTCU really limp mode my car?
dive deep and saw P140404 exhaust flap 2 malfunction.
where is this location and is it a easy fix.
Last edited by C63_boo; May 30, 2025 at 07:08 PM.


If you have a PCV leak under WOT then I would think a P1CE700 or P1CE800 code might be present. I'm not familiar with the Autel menus but try going through some menus to see if you can manually actuate any PCV valves to open or closed and re-do your smoke test.
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however, I try to find the function to turn off the exhaust flaps and couldn’t find it. Only thing in the Autel is multipurpose exhaust regulation and it came up saying none installed, which is odd.
i took off the flap assembly on both mufflers and they seem to be working. I can see both spring moving about 1/4 turn each time I turn the car on and off. But no movement when I switch it from C to S+.
can the Autel take my car off of limp mode? And how?
Last edited by C63_boo; May 31, 2025 at 06:08 PM.
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I can use the Autel to open and close the valves but seems like the driver side is stuck. Will try to fix it and report back.
so frustrating.
however, in the mix of things. I accidentally went in an calibrated my suspension and now the car suspension is in limp mode. Does anyone now what our stock level suspension value is set at?
2019 sedan C63 with the stock black 19” wheels
front right
front left
rear Right
rear Left


I’ll try to reach out to the person you mentioned.
hopefully someone here had some knowledge on how to do this ADS Suspension level calibration.
there is one issue that I have. I enter a few number between what was given and it errors out.
Not sure where the +\- in the system to even make adjustments.


however, did some more digging and notice that one of my height is out of range, 127, you can see it in the diagnostics screen. So I’ve been jacking the car up and down since it’s reading mm instead of voltage. this is done on all 4 corners to get the range back into spec. Notice the high 127 was due to a bad installation of the level sensor, installed reversed after camber arms were installed. Got that corrected. Now just waiting on the car to reset 10-15 minutes with closed and locked doors. Will report back if I get it corrected.
here’s what I’ve done. All four corners, raise it until you are within spec, this is better than voltage reading.
then, input the values display on the diagnostic, front angle range was -4 to 2.8
and rear was -2.5 to 1.9
take values in between. Mine was -.8 front and -.5 rear.
the car was happy and accept it.
Last edited by C63_boo; Jun 3, 2025 at 06:47 PM.
Last edited by C63_boo; Jun 3, 2025 at 06:37 PM.


