E300 Turbodiesel MAP Sensor - PeachParts Mercedes-Benz Forum

mdisav · #1 05-05-2009, 05:45 PM

Does anyone know the bar rating of the stock denso map sensor for the E300 Turbodiesel? # 011 542 07 17

I am leaning towards 1.5bar but I need a 2.0bar. I want to run 25psi but the overboost is coming in at 23 psi and cutting the fuel. I had Oliver at speedtuning raise the overboost to 27psi but it is still cutting the fuel at 23/24psi.

So something is telling me I am maxing out the sensor since it is not able to tell the difference between 23-27 psi.

I definately have enough fuel thanks to Oliver but I just need to get the turbo to take full advantage.

nhdoc · #2 05-05-2009, 06:18 PM

My understanding of MAP (which means manifold ABSOLUTE pressure) is that it reads atmospheric pressure plus boost. My scangauge will read MAP and it concurs with this in that the idle reading from the MAP is usually right around 14.9 PSI which is atmospheric pressure. It will peak at 30-32 PSI or about 1 bar over 1 atmosphire (also about 15-17 PSI of boost). So, if you want to boost to 25 PSI you need an MAP sensor which will read up to 40 PSI or about 3 bar maximum. I would guess the stock MAP sensor will read up to at least 2.5 bar since mine reads around 2.2 bar at peak before the wastegate opens and limits boost.

mdisav · #3 05-05-2009, 07:29 PM

That makes sense to me Marty. Thanks! Looks like I need a 3bar.

KarTek · #4 05-05-2009, 08:29 PM

I believe that full fuel is allowed by the ECU at something less than full boost. You may want to confirm this with Oliver as well as find out exactly at which boost level full fueling is permitted.

At any rate, my truck has a more sophisticated fueling system but it uses a similar set of sensors to provide fuel control information. On the truck, a common solution to the overboost code is to insert a simple, cheap air pressure regulator inline with the MAP sensor. The regulator is set to a pressure slightly less than that which sets the code.

There have been numerous attempts to create an electronic solution that limits the signal from the MAP to the ECU but none are as successful as the regulator. The regulator also serves the purpose of protecting the MAP from excessive damaging pressures.

mdisav · #5 05-05-2009, 09:49 PM

I am going to get a 3 bar map and see what happens. He did say he changed the overboost value to 27psi.

The 3 bar map should produce the proper voltage to have things the way the ecu wants it to not set the overboost.