Ok I just got the two bar map sensor from GM. Do I need the stock map sensor, or the GM sensor replases it? I will bee using the AEM EMS soon, does it make a diference how the map sensor is conected?

 

It will replace your factory map sensor when you get the EMS. You cannot use it with your stock ecu.

You'll have to connect it to the intake manifold via a vacuum hose.

May I ask why you got the 2bar? For that 2 extra psi of boost you can run on it past the factory sensor?

 

I was told that the stock map sensor craps out at 10 to 11 psi and the GM two bar sensor is good to 15 psi, is this right?

 

the factory MAP is a 1bar...I know everyone says it craps out at 11psi, but I've heard people say it's good to 14 or so, and it doesn't make sense that it would be good for less...I think most people step up to the 3bar so that they can go above 14psi...

on a related not; why can't you use it with the stock ecu? The three bar puts out 1.6volts at atmospheric, so I'd think you should be able to run a few psi of boost with larger injectors and NO other fuel management using that (since the stock MAP puts out 2.8v at atmospheric) any thoughts?

 

Factory map sensor is good to about 12psi. The 2bar will get you a claimed 14.6psi but GM consistency is pretty lame so it might be anywhere between 14 and 16psi at max voltage.

 

The factory map sensor is a ~1.8 bar sensor. 1 bar sensors can only sense vacuum.

The sensor is going to read max voltage between 11 and 12psi. Sure you can boost beyond that, but your engine management is not going to know about it, but if you are OK with running rich at boost levels slightly lower than 14psi (~12psi), you can run 14psi but tune your ~12psi for the fuel necessary at 14psi. Then when you are at 14psi, your sensor will still be returning max voltage, but you will have enough fuel. The downside is that at 12psi you'd run rich.


The voltages aren't on a "sliding scale". Voltage rise is at an entirely different rate between the two sensors. Hence, the voltages do not directly correlate, and your car would run terribly. You'd also need some very well selected injectors (say 496.2435 cc/min hehe). The min voltages are different on the factory and GM sensors.

Dustin

 

Thanks for the info Dustin, good to have all this cleard up

Does enyone know how to wire the GM map sensor?

 

http://www.hondata.com/3barinstall.html