M104 suddent rush of power at 3500 RPM
 

Is this common for a M104 to lag' at first and suddent rush of power at 3500 RPM (it feels like it has a turbo :eek:) or is my exhaust is clogged??

Might be when variable intake runner length valve cycles???????

M104 has a valve in the intake manifold that effects a change in the length of the intake air path. Kinda like headers except for the intake side. It's purpose is to tune the intake to match load and RPM. Maybe someone more knowledgeable can explain better................

J. M. van Swaay

Completely normal,,,, just sit back and enjoy.:D

yeah it just feels weird... i found a wikipedia on it,

http://en.wikipedia.org/wiki/Variable_Length_Intake_Manifold

I bet there is a sudden rush of fuel right around the same time......and a sudden rush to single digits for mpg's.... :D :D ;)

Your right, once i did that my gas needle when down for a few seconds and when up back...Like what any High output jeep engine dose, Suck aton of fuel and then release it back to the tank...:D

So, ... where does it store this ton of fuel??

You're probably seeing the fuel slosh away from the sending unit.

Rush
 

That's about the point when the intake manifold flap changes position but there is no way you could call it "a sudden rush" in my experience. More likely a slight power increase. Sounds like your engine is down on power at lower RPMs.

Mine all get a noticable boost around 3200rpm when the flap opens, it's significant.

The Resonance flap for runner length opens @ 3350 w/WOT...and the Cam Advance sol. advances the intake valve timing 20 degrees at 3000. So, between the two, there is a considerable torque difference.

Same here with mine. Still makes me smile too.

Well my tranny has some issues with shifting, it wont shift past 2300 unless i shift it my self....But it still have lots of for low end power though :cool:

I'm not sure if it is a huge power boost or a mild power boost with a huge sound boost. :) I've noticed it as well, it just seems rather un-Mercedes-like to have such a sudden, dramatic shift in power delivery and sound when the intake flap switches over. Not that I mind. :)

Yeah I too notice that, at first it smoothly accelerate, but once it passes 3200 rpm it roars it's way up, as what mr.project said unmercedes like feel

The 104 HFM/SFI is a high performance engine. So you have to expect the sport performance .
There was a design leap foward when they got rid of Distributors and went with full Electronic Sequential FI. And b/c of Full electronic management, it was easy to add cam advance, HFM metering, and SFI, along with the intake resonance system. A great achievement and quite modern for that time.