Yeah, it's the same idea as on the 2G DSMs. In fact, it's the exact same part number. It's used to check that manifold pressure changes like it's supposed to when the EGR valve is activated. Once appropriately hacked, the ECU can use that input for datalogging boost pressure just as well (or wideband data), with a different sensor of course. It's a standard 0-5v input.

Thomas Dorris

 

Actually you guys are right about the Map sensor but it might be confusing to some people.

1 bar on a Map sensor reads atmospheric pressure = 14.7 psi.

This is NOT 14.7 psi on a boost gauge though. This is 0 psi boost.

14.7 psi of boost would = 2 bar on a MAP sensor.

Thus this MAP sensor cannot read anything past atmospheric pressure, which is fine only for a NA vehicle.

 

My master plan is to have a PC in the car that logs all the sensors at 20 or so a second while also logging my GPS coordinates. This would come in REAL handy for track events and learning the fastest method through certain sections . This however is down the road, unless I get a sponsorship to do it. I need to buy another set of rims, tires, brakes, harness to get on the track first. Then I'll play with the pc in the car...

 

So can someone go over where exactly these sensors are in the intake and maybe some of the sensors on the exhaust path.

Something like, a hole -> air filter (1 atm = 14.7 psi) -> MAS (vaccum, maybe 5 psi ) -> intake turbine (WOT, @18.5 psi) -> intercooler -> BOV (hopefully not leaking and psi) -> Throttle plate -> throttle body where the MDP sensor (still same, 18.5 psi) and A/F sensor -> cylinder -> wastegate valve -> exhaust turbine (if waste gate closed) -> downpipe -> o2 sensor -> cat -> another o2 sensor -> muffler...

This was just a guess from what I know. Can someone explain the sensors in more detail and place them in the right order and also the typical pressure at that point.

Thanks,
smanders

 

Shiv mentions the MAP sensor in this thread...

https://www.evolutionm.net/forums/sh...r&pagenumber=5

 

smanders: There will be pressure drop across the piping and intercooler. So whatever pressure you see at the turbo will be higher than what's in the manifold. Check out the plots from APS on this page about their aftermarket FMIC.

APS FMIC

 

That makes sense because temperture directly affects pressure so with the temperture drop across the intercooler, the pressure will drop as well.

This is good stuff...

 

To tell you the truth, I am surprised that the ECU lets you datalog the MDP sensor through the OBDII port. You can't do that with an Eclipse.

 

MAP?? You can on a WRX. I have done it on my friends. It reads fine. It never hits a max value.

 

No, not MAP. MDP - Manifold Differential Pressure sensor.

On a Mitsubishi it is only used to test the EGR valve operation.

 

Wait. I think I just figured it out. I bet you were not datalogging the MDP sensor. You were probably datalogging the barometric pressure sensor in the MAF. That sensor just measures the atmospheric air pressure. Along with the air temp and the Karmann frequency, the barometric pressure sensor in the MAF allows the ECU to calculate the mass airflow of the air entering the engine.

The baro sensor wouldn't vary much during a single drive.