Can our factory MAP sensors handle high boost? Friends car goes to failsafe at high speeds (5000+ rpm) with 185mm crank and supercharger under pulley. IAT's are in check @ 110 degrees on hard runs. Car starts to have hesitation and rough idle after hard run and then is corrected after restart? Started recently after having current set up for over 5 months now.

 

I Basically had the same exact situation, (Same exact setup - 185mm lower and smaller pulley up top) and then it got progressively worse and now i'm having a misfire situation.
Here is a link to my tread:
https://mbworld.org/forums/showthread.php?p=5835004

BUT IF YOU FIND A SOLUTION PLEASE LET ME KNOW, I am going crazy because of this issue.

 

You need a MAP clamp. Right around 17.5psi is the limit without one. Car will go into limp mode or something at that point.

 

What is a MAP clamp? I looked online but couldn't find out anything about It on an E55? If you can direct us to the clamp it will be much appreciated!

 

Just a word of caution about map clamps. They are rather dangerous to use. A map clamp limits how much voltage the sensor sends to the ecu and yes it keeps it from hitting a certain voltage and possibly setting a fault code. But at the same time it doesn't actually allow the ecu to know how much boost is actually being made. Altitude and air density change will greatly throw a tune way off even it its somewhat tuned for with the clamp. Map clamps were initially made for cars that both used map and maf sensors, on those cars you could clamp the map voltage and still had accurate metering from the maf.

 

If this is the case, then is there a better solution such as a higher resolution MAP and tune? What size is ours? 3 bar?

 

The factory sensor is either a 2 or 2.5 bar, can't remember. The sensor is not the issue the ecu is the issue.

 

Where is this sensor located? I seem to have rough idle issues also intermittently.

 

When you say ECU, do you mean the tune isn't right?

 

I believe he's saying the ECU doesn't know how to handle the amount of boost it's seeing, not that the tune is bad.

 

Factory MAP sensor is 1.1 bar. Good to @15.8 psi. Something is adapting. Never a problem before......so my question is why now with the vehicle? We are going to disconnect the battery overnight and see what that does. This problem is known throughout the forum with these mods and I'm curious why it's a damn secret fix?

 

Failsafe/limp is limiting boost to @15.5 psi. Our maps can't calculate 17.5 psi

 

Max readout of MAP sensor is 5v. Can't tune around it.

 

@ the Y-pipe on the intercooler. Supercharger has to be lifted to get to it.

 

The MAP sensor is made by Fuji Electric

http://www.fujielectric.com/products...resensors.html

Part EP9631-R3A

It is 2.5 BAR Absolute

 

There is also a Bosch made one, would be interesting to compare the spec of the two different makes. Could that be the missing piece for the 82mm TB issue???
If the map sensor had a slightly different operating tolerance or curve character.

 

+100. Should only use MAP/MAF clamp if using additional injector/controller that can read beyond where you are clamping otherwise you are tuning in the dark. I guess I never gave it much thought on the E55, just assumed there was plenty of margin since no one had brought it up.

 

Factory is 1.1 bar. Are you saying otherwise?

 

The sensor supplied by MB part A 005 153 7228 which one of the manufacturer's Fuji Electric part EP9631-R3A is 2.5 absolute sensor.

 

absolute pressure includes atmospheric pressure. Atmospheric pressure is 1bar. Therefore, we have a 1.5bar pressure sensor. Almost 21psi can be read by the sensor.

 

Incorrect. So you are saying our MAP allows over 30 psi? lol

Renntech knows of this problem with our sensor as do other tuners. Let me explain as an example...... @15lbs of boost our MAP is near max output of 4.5v and tells ECU to allow 1 part fuel.Now at @5v our MAP sensor is maxed and allows 1.5 part fuel and triggers a lean code that causes the limp mode. If, and I say IF, a tuner can tell the map to allow more fuel at different voltage.....problem solved. Most likely, we will need a different MAP sensor.

 

Where are you guys getting this? How about someone talk to Renntech or a master Mercedes tech that researched it. Oh, wait....I did.

 

It is simple mathematics.

1 bar = 14.5037 psi

Atmospheric pressure at sea level = 1 bar

1.5 bar = 21.7557 psi

2.5 bar = 36.2595 psi

An absolute pressure sensor is reading 1 bar of pressure at sea level. We have a 2.5 bar absolute pressure sensor. It can measure up to 21.7557 psi above atmospheric pressure. The problem is more than likely the scaling of the sensor data via the ME control unit, or fail safe that has not been found in tuning yet. There is much more involved in our vehicles than tuning the engine control unit. Numerous control units have control over power out put. I am one of those, and I have researched the matter.

 

The math is not in question, professor. It is your ability understand we have a 1.1 bar Map sensor. lol

Apparently, you have not. Call Renntech. Call Eurocharged. Hell, just drive a m113k that is producing more than 16+ lbs of boost and get back with me.

 

Where do i get this simiple?

I have MB STAR which includes WIS & EPC you can look up the exact part number for the MAP sensor.

I have a map sensor from MB its above it clearly states the part number of MB and the actual manufacturer Fuji Electric. The specifiication of the MAP sensor is public information on the website but here it is again.

http://www.fujielectric.com/products...resensors.html

and here is they part number again Part EP9631-R3A it has an operating pressure of 20 - 250 KPa abs, 250 KPa is 2.5 BAR absolute.

You are confusing the physical limits of the sensor vs the data held in the tables in the control units, the MAP sensor is clearly a 2.5 BAR absolute sensor.