madfast

i was wondering what type of sensor reads the boost on my 02 c230 kompressor......would it be like a MAP sensor or the like? and what values are implemented in this sensor, for example- variable ohms (resistance) or whatnot. also, where is this sensor located, any pictures?

Buellwinkle

Nothing reads boost or even extrapolates boost from any sensor in your car. If you want to know the boost, get a boost guage $15-80 and hook it up.

white_w203

you can get a boost gauge and they run around $50-$60. the gauge tapes into a vacuum hose to tell u how much boost there is.

madfast

no, i know exactly what a boost sensor is and how it works

i installed a wideband 02 along with a stoichometric guage and a boost guage in my 84 nissan 300Zx turbo automatic, and a boost guage in my my 86 300ZX turbo 5 speed, along with a turboXS dual stage boost controller, and HKS SSQV positive action type non-recirculating blow-off valve.....i'm very fluent with gasoline and diesel performance modifications, electrical systems, and maintenence, on both two and four stroke gasoline and diesel engines, both naturally aspirated and forced induction.


however, i'm not fluent with this particular vehicle......maybe i should have asked the how the boost is bled off at 5 psi. i understand with a supercharged application that swapping out the pulley with one that creates more boost is one way to increase boost, but i was under the impression that the engine control unit bled off the excess boost after 5 psi. i had read that the full boost is acheived early into the rpm range on this vehicle, leading me to beleive that higher boost is possible, but not acheived via an electronically controlled boost regulator valve of some sort.

i took a guess and figured that whatever device bled off the extra boost was electronically controlled, and that it used a sensor. (you figure, its german, so its complicated, yah? haha) if a sensor was implemented, then there are ways to trick the sensor, albeit pressure valve to get the sensor to see lower boost, much in the way a simple ball-and-spring boost controller tricks the stock wastegate in a turbocharged vehicle, or use resistors or whatnot say if it was a MAP type sensor. any type of lean condition created by tricking the car into seeing lower boost while higher boost is created would be compensated by the O2 sensor.

just working on a few theorems. any good people who know rediculous amounts of tech on this car?

Capt Nemo o2

There is no intake manifold pressure sensor? Isnt that one of the things that can be monitored through OBDII?

Buellwinkle

I know the 2002 C230 engine as well as many, I can assure you there's nothing that measures boost in the M111 motor. Boost is purely based on rpm of the s/c pulley, the higher the rpm, the higher the boost, this is not a turbo, nothing like it, there's nothing to bleed off or regulate. To conserve fuel, MB uses a bypass valve that bypasses the s/c when operating in a low load conditions. In high load conditions, such as wide open throttle, the bypass valve closes allowing any and all boost out of the S/C through the IC and into the intake, the higher the rpm the s/c pulley spins, the higher the boost. On that motor, the maximum boost as measured at the throttle body is around 6-6.5 (automatics don't rev as high, hence slightly lower boost). With a pulley kit, depending on size, I've seen as high as 11 1/2 PSI, the problem is somewhere after 10 PSI, the power required to spin the s/c exceeds the power gained. This is why companies like Kleemann, ASP, Renntech, Vaeth chose to make the overdrive crank pulley they sell a certain size. Like I've said, I've seen a bigger pulley than what these tuners have done and the HP/Torque is the same, more boost at that point does not translate into more power. I've run many, many dynos on my old 2002 when I had it, different size pulleys, intercooler and software, there's really nothing that can be done to control boost in any way other than a bigger pulley.

Also, if you really think the O2 sensor is going to compensate for a lean condition at ful throttle then you don't understand how ECU's work. At idle, during warmup and at full throttle, the ECU can't rely on the O2 sensor, At warm up it can't rely on the O2 sensor because it's cold and doesn't provide accurate numbers, at full throttle it's not fast enough to respond accurately so the ECU runs in what's called open loop mode and ignores the O2 sensor and relys on fixed mappings. What some people do for additional fuel is to put larger injectors or higher pressure FPRs so that for each injector pulse, more fuel is introduced. Unfortunately, the FPR is part of the fuel pump inside the gas tank so this hasn't been done by anyone (it is done on the older C230 M111 engine where the FPR is on the fuel rail). While the engine does run a little lean at 10 psi, it's not that bad and it's for such a short amount of time nobody has had problems with this except for one person that ran NO2 and a pulley kit on the track repeatedly. His mechanic bought the car, rebuilt the engine and put in a turbo and got 300hp but put it back to stock for his wife. With that hp, he burnt the clutch out quickly but who know's, the previous owner spent a lot of time at the track, the clutch may have been on it's last legs.

Also, before you get too tricky and short a sensor, keep in mind the ECU module costs about $2K installed and you can't use a used one.

Good luck with your tuning efforts.....

madfast

:-)

Buellwinkle

There are actually ECU parameters I tested that enrich the fuel mappings but believe it or not, the additional fuel reduced HP.

firestar

Which ECU parameter did you mess with? Could it be that while enriching the fuel it also retarded the ignition timing. Most engines that run ~14:1 AFR will see some gains when enriched to 13~1 or so AFR.

firestar

On the M111, the boost sensor a.k.a. MAP sensor is located on the manifold somewhere below the throttle body. It outputs 0~5V in proportionate to manifold pressure.

Not sure bout the M271 but should be somewhat similar.

Buellwinkle

Yes and no, MAP sensor measure vacuum pressure, sure it puts out more voltage with more vacuum but I don't understand how you would measure boost since that would be negative voltage.

As for the ECU parameters, they have 2 that we tweaked, one was for timing and they scaled it by octane, so the higher the octane number you put in, the more advance it would introduce, at least in theory as none of us know what's in their code. The second thing was for fuel, it was set as stage 1, 2 and 3. If you search some 4 year old threads you'll find out more. Nothing we tried produced more power on the dyno, every option other than the stock option list power. The theory back then was that these were options that were put there for countries where fuel quality was questionable.

pugguy2001

Are these directions to install a boost gauge the same for the m271 engine. The illustrations are awesome. I am just hoping they are the same or just not harder. Has anyone found a single pillar gauge set up yet for the 2005 c230ss What gauges have you guys used? http://www.mbklasse.com/forums/showt...ht=boost+gauge

Benztecg

Actually map sensor is boost sensor in 111, and if you bleed vac. after sensor
and measure boost you will see gain 2-3 psi. the only down side to this mod
check engine light will turn on.Oh and big torque gain 4800 to red line.

arell

Ok, I've been hacking up the electronics lately.

Here is the thing.

I've played with these sensors:

The air mass sensor (MAF)

The map sensor (MAP)

and

The atmospheric pressure sensor (BARO)

Hooking up an OBD2 scanner and monitoring the data reveals that:

When engine running, disconnecting one after the other the MAF, MAP and BARO OBD2 still shows inlet manifold pressure data and engine still makes smae amount of power as with the 3 sensors connected.

Where is the fuelling map sensor which I am unable to locate? anyone know.

the BARO is located below the airbox (3 wires, the middle is the signal)

the MAP sensor controlling boost is located further behind looks similar to the BARO but with the pressure port into the inlet manifold.

the MAF is self explainory.

The engine makes no glitch when those above sensors were removed except for setting off the check engine light.

arell

Ok, I've been hacking up the electronics lately.

Here is the thing.

I've played with these sensors:

The air mass sensor (MAF)

The map sensor (MAP)

and

The atmospheric pressure sensor (BARO)

Hooking up an OBD2 scanner and monitoring the data reveals that:

When engine running, disconnecting one after the other the MAF, MAP and BARO OBD2 still shows inlet manifold pressure data and engine still makes smae amount of power as with the 3 sensors connected.

Where is the fuelling map sensor which I am unable to locate? anyone know.

the BARO is located below the airbox (3 wires, the middle is the signal)

the MAP sensor controlling boost is located further behind looks similar to the BARO but with the pressure port into the inlet manifold.

the MAF is self explainory.

The engine makes no glitch when those above sensors were removed except for setting off the check engine light.