Exactly which engine is M140.990?

Jens,

My '97 E320 104.995 has a definite turbine like power surge when accelerating into higher (4,000+) rpms - as if a flap opened. Below that is fine but the change is quite noticeable - the rpms really shoot up! The motor is described as having ME 2.1 sequential multi point fuel injection, a 2 stage tuned-resonance intake manifold and variable intake valve timing. The resonance system is described as a butterfly valve that routes air along longer passages at low rpm to boost cylinder charging for greater low end pull. At higher rpms the valve directs the air flow along a shorter path to provide larger volumes of air for greater top end power. Sounds to me like the "trick" increases the motor's low end torque by using ram air flows. Another way to keep down the rpms and so raise the car's fuel economy.

Not the technical answer you sought but might help solve the puzzle.

Tom

Thanks Tom

This was exactly the kind of answer I sought for the second question (how does the '94 and later model drive).

This is also how I feel it.

But I thought the later model would have a better "fill" in the torque curve from 2000 to 3500 rpm as seen in fig. 37 (if you can see it). As also seen here, the resonance flap is open between 2200 and 3200 rpm to ensure this fill.

Still I wonder whether my engine is 3,0 or 3,2 litres. As judged from its behavior, it is 3,2 litres but without resonance boost (which probably makes the behavior more noticable).

/Jens

T.G. Lambach wrote:

Definitely the 3.2L engine. Confirmed by several sources.

Jens,

"I wonder whether my engine is 3,0 or 3,2 litres."

Isn't DK road tax charged by engine size? If so the car's registration will be another clue.

Tom

Thanks Tom and Tiger

So, it must be the 3,2 litres.

And Tom, road taxes used to by by weight, but has now been changed to fuel economy. This is valid for cars produced after the change date. The previous ones still go by weight... unfortunately for a W140.

By the way, the engine was most probably modified by Brabus as a retrofit somewhere around '94. I am not completely sure of it, but interior was changed to leather, the rims to Monoblock III, the entire suspension changed and at least the exhaust is Brabus. The camshaft cover was also painted red, which indicates that Brabus at least touched the engine. From what I can find out, their standard modification for this engine was an increase in engine volumen to 3,6 litres with 285 hp.

I do not intend to take the head off to see the cylinder diameter, but maybe I should take it to at test stand to verify the power. It does have quite some power above 4000 rpm, so it could very well be true. And mayby that's what makes the lazy feeling in the 2000-3500 rpm range more apparent.

Anyway, driving with A/T in normal situations seldom brings it above

2500 rpm unless you really accellerate. This is reasonable OK when starting from zero, because the shiftpoints change more or less proportional to the gas pedal. And when you drive some 50-60 mph and accellerate, the A/T willingly shifts down to 3rd bringing up into more powerfull rev's. When driving below that, it should likewise shift down to 2nd to achieve the same seamless power feeling. But it doesn't unless you kickdown, and then it may even go to 1st, making use of this option a bit uncontrollable (or rather wild).

Do you have any experience whether this is normal?

/Jens

".... road taxes used to by by weight, but has now been changed to fuel economy."

Something that's sorely needed in the 'ole USA.

I can't compare driving experiences - I drive gently and my car's transmission is the electronic 5 speed overdrive.

If you're willing to spend the money a dynamometer test will tell you if the motor is doing all that it should be.

But then what?

If it's OK then YOU'RE the one who's dissatisfied, or, if the motor lags, then what's to be done to it?

Vexing.

Tom

P.S. I was thinking about checking and possibly raising the turbo boost pressure in my 26 year old diesel - but then thought .... Why? I don't floor it to maximum rpms now so I leave it set to OEM specs.

Oooh... Brabus modified engine? That must be exciting and powerful.

:o)

Well, I don't drive that wild either.

But when driving some 30 mph, it will be in 3rd around 2000 rpm. accellerating 2 tons to overtake without shifting down is sloooow. And it does not shift down unless you force to by manually shifting or kick-down (in which case it goes beserk, which is not what I want).

That's exactly why I'd like a more smooth shifting.

Anyway, I just wanted to check whether it was normal, or if something could be done about it.

And.... I am not dissatisfied with it, and yes I will take it to at dynamometer to verify the power.

And.... maybe I will fit a supercharger, not to increase high rpm horsepower but to boost low rpm torque for the smooth ride.

Let's see if it's plans or just dreams. I think the last.

/Jens

T.G. Lambach wrote:

is the electronic 5 speed overdrive.

motor is doing all that it should be.

what's to be done to it?

pressure in my 26 year old diesel - but then thought .... Why? I don't floor it to maximum rpms now so I leave it set to OEM specs.

I'll find out whether i was modified or just painted.

I have not driven other 300S's to compare with, but yes, on the highway I don't lack power.

Tiger wrote:

...

Correct designation is M104.990 (one zero four).

It has a displacement of 3199 ccm, 6-cylinder in-line, bore x stroke = 89,9 x 84,0 mm, compression ratio 10.0:1, 4 valves per cylinder, two overhead camshafts. Maximum power output is 170 kw = 231 PS at 5800 revs, max. torque 310 NM at 4100 revs, LH-Jetronic.

As later not only the engine, but also the model designation and the body were changed it was:

04/1991 - 05/1993 = 300SE, M104.990, old body 06/1993 - 02/1994 = S320, M104.994, old body 03/1994 - 09/1998 = S320, M104.994, new body (face-lift)

E-Class W124 got the newer engine version earlier, in October 1992: More torque, more max power and max torque is avilable at lower revs.

3,2 litres. There was never any 3,0 litre engine in the W140 series.

That's why there later was the .994 version.

Juergen

All that is no proof of anything else than that (interiour, suspension, exhaust and wheels were changed as well as that) someone has painted something on the camshaft covers.

Juergen

Let it be a dream. The engine was not designed for a supercharger.

Juergen

Jens,

"it does not shift down unless you force to by manually shifting or

kick-down (in which case it goes beserk, which is not what I want)"

That's a description of a transmission that's not making partial throttle down shifts. Not the engine's fault but the transmission's fault.

If it were my car I'd investigate what is supposed make the transmission down shift on partial throttle openings is it controlled by a cable, like in the '70s and '80s or engine vacuum or the engine computer? (I don't know.)

This is a sophisticated transmission so don't let someone give you the all too frequent automotive repair reply: "they all do that".

Tom