AMGSuperSaloon

Hi everyone, I've looked around a bit and haven't seen this issue posted elsewhere and wanted to get some ideas.

I bought my pre-owned car 2 weeks ago and have been blown away with just about everything. The power delivery is amazing, except for the last 2k RPMs. It's not bad, but just seemed different than the mid range grunt this car has.
I filmed this video (its **** and I'll try to refilm a longer pull soon, sorry) but it highlights the issue. The car builds up nicely and then at about 4k RPM the boost completely falls off. Is this normal? If it is why for the love of God would they do this? 3 of my previous vehicle were very turbo-dependent and I understand that turbocharged vehicles have "peak" and "hold" levels, but this appears to be 0 boost, not just a slight taper

Thanks in advance for any and all help

Cheers

shardul

iTrader: (1)

Start off by checking all the clamps on the charge pipes.

AMGSuperSaloon

I wouldn't think it'd be able to get to peak boost levels like it does if there was a leak, but I'll run through it and see if I see any mechanical issues/leaks.

Thanks

shardul

iTrader: (1)

Valid point.
I would also scan the car with STAR DAS to see if there are any soft codes in the ECU and clear them out. (These codes will not trigger a CEL)

tekfoc

possible pinched wastgate actuator vacuum hoses . there is tsb from mercedes for this .
take it back to mercedes for warranty repair.

AMGSuperSaloon

Additional video thru 2nd and 3rd gears... I can definitely see how this can be from a collapsing vacuum line to the WGA

RDOCA

[QUOTE=tekfoc;7302227]possible pinched wastgate actuator vacuum hoses . there is tsb from mercedes for this .
take it back to mercedes for warranty repair

this is repair for this problem

AMGSuperSaloon

[QUOTE=RDOCA;7302676]Wow! You guys are great! Thanks for the quick replies. I’m almost nervous thinking about the extra top end this will have after this gets resolved. I’ll take it in to MB in a couple weeks when I have time and let them get to work.

Cheers

RDOCA

[QUOTE=AMGSuperSaloon;7302682]You can see what they did in above attachment.
Mine was an intermittent loss of power and showed up as only 275 HP on center screen and only partial boost on screen in front of wheel on boost gauge.
Has not reoccurred.

amg8

[QUOTE=RDOCA;7302689]Hi RDOCA,

Do you happen to know if this affects MY2017 build 12/16 ?

AMGSuperSaloon

[QUOTE=amg8;7302730]Yeah it’d be interesting to know if this is just an early build issue. Mine is a 2015 by the way

RDOCA

[QUOTE=AMGSuperSaloon;7302741]I don't know the range. Mine is a 2016 sedan made in Aug 15.

AMGSuperSaloon

Just dropped my car at the dealership today. I did get a little of the "deer in headlights" look when I used words like "wastegate actuator vacuum line" and "limp mode" but I'm hopeful they resolve the issue. I'll keep y'all posted

KJ

Don't worry, the service advisor has no idea about this stuff, they just pretend that they do by repeating what's on the service papers.

The tech will know exactly how to diagnose and fix this.

AMGSuperSaloon

God this was spot on. My service advisor just nodded and smiled and when I went on a drive with the shop foreman after everything was done he knew exactly what the issue was.

He said only one of the vacuum lines was defective and that was replaced. The issue is now completely fixed and the car feels great.

Thanks to you guys for your help in diagnosing this so quickly.

Johnny Poon

I’m having trouble with this one guys. I went in to try to get it fixed but they said because it wasn’t throwing any codes or check engine light they are unable to fix it? What should i do? Tell them about the soft codes? Should i basically walk them through this? I’m tired of seeing the boost pressure drop and i can significantly feel the power loss. I also tested the 0 to 60 out to see as well and I’m at 6.3 seconds with that.. it’s so frustrating please send help.

nobbyv

I'd say it's time for a different dealer. If yours is unwilling to do the bare minimum of troubleshooting beyond running a code scan, they probably don't deserve your business. If for some reason you have no choice, did you take a ride with the tech and show him the HP screen? It might seem a little hokey, but it's a good quick check to see if there's an issue. You're not going to hit 450+ on every pull, but if you're routinely topping out around 250-300, it should be obvious there's a problem.

Johnny Poon

unfortunately i have the 2015 models and they don’t come with the HP screen unless there’s like an update for it. Other wise I’m **** outta luck and it’s all based on the “techs” feel. He says he feels no lose in power and that the gauge is “normal” to do such a function. I watched videos of the same car and none drops at 5k rpm. I thought they fixed it but after test driving it, it was still the same. I tested out the 0 to 60 to see how fast i get it up to 60 and boy it took like 6.8~7 seconds to get to 60.....

nobbyv

If you don't have another dealer you can use, maybe just buy the part yourself and replace it? Someone on here might be able to post their work order from the repair complete with part numbers. Can't imagine it's that expensive.