cls5504matic

Pushed the car a bit with an buddy in a v8 m3. On the highway coming back 5 gear high speed i would get a cut of power. But not the shaking.

All other gear changes were solid. Is this a fuel pump, a torque converter, tranny issue or something else to investigate.

I kind of recall some of the higher power m278s stock fuel pumps not keeping up. And i likely need to do a fluid change on the tranny at 6 years and 27k miles

blaise

Are you stock or tuned? What speed did it cut off at? Stock mph limit is about 130, i believe.

cls5504matic

Tbh i dont look at the speed much. I just focus on the road. I guess it may be the limiter @ 4200 RPM in 5th gear (1, 2.47 25.85)

Dblok1113

I believe cls550 is tuned so there shouldn’t be a limiter

cls5504matic

Its not limiter. I can smoothly drive faster and switch gears fine. Its when i gun it in 5th. Feels like im hitting a wall and pulls gas or something. Not a bunch of jerks. no misfires just feels like i hit a wall and i pull back and can drive fine.

No codes.

thinking it is fuel pumps. Wouldnt injectors throw codes?

Roop94

That's weird. I was racing an M3 a while ago and was around 125mph, don't know which gear, and everything was fine.

Yeah, if injectors stopped, it should throw a CEL. Or if the injectors stopped working for a short time, the CEL should flash and maybe go away once they're back on. Maybe check for any Pending Codes?

Like did it not move at all in the 5th gear or was it slumping a little?

cls5504matic

like i hit a wall and was thrown forward. It’s only like WOT, high accel/jerk in 5th. Only in 5th that i know of but definitely not an issue in the lower gears.

Roop94

Damn. I wonder what could be the cause of that. Could it be a possible clutch pack wear in the trans? Low trans fluid? And it's kind of weird that you never got a CEL either.
I'm just throwing random questions and see if it can lead to something else.

cls5504matic

Thanks for the ideas sir. Currently I’m going to change the tranny fluid and i worked to reduce EGT.

I guess I’ll put together a video for that.

Roop94

I need to change the Trans fluid as well. I don't know or think if it was replaced before I bought it. It's currently at 75k miles

wrexed03

Did you ever find out what the cause of this issue was?

cls5504matic

Yes Eugene at Morendi helped see out -- overboosting

DigitalDisaster

Was this the tune or hardware issue? What did you do to fix it and did you really notice a difference by adding the filter spacers?
Thanks,
Bob

cls5504matic

I'm not sure why my car was overboosting. I guess I was running free flower intake and exhaust then the tunes anticipated. So a bench tune optimized for a stock cls 550 didn't work. Morendi flashed a bench tune then logged it and changed the tune, by adjusting torque to load and max airflow to address it.

my takaway personally is that morendi's tune process right now of using a bench tune then logging is superior than a my genius with bench tune.

I'd also guess air intake is a pretty big bottleneck. the stock air filters are huge, and take up a lot of the intake tube, aftermarket filters are less than half as thick. but upd does remove them completely from the air intake tube. DTK (RIP) and I were discussing this once on FB. He mentioned he didn't think they did much because they only increased hp by about 10-20 hp and felt that was within the margin of error. But he did feel the black boost, and his custom intake unlocked enough power to be statistically significant. like 40 hp.

I think at this point I would go with black boost when they are on sale. There are some custom intakes out there including scorpion style intakes with top mount intercoolers. which would be a significant gain, more than 40 hp with a tune maybe 70 hp.