3 Bar Map Sensor

[BenPutnam]

Anybody know what a 3 bar map sensor is and what the advantages are?

 

[clusolynn]

3 Bar MAP sensor...

MAP stands for; manifold absolute pressure. It is a little rectangular shaped sensor, usually located on the passenger side firewall on a stock GN, under a small metal bracket within inches of the A/C evaporator housing. In most vehicles, it measures vacuum then sends a signal to the computer to calibrate fuel adjustments. In the Turbo Buick, it measures boost levels from the turbo, sends a signal to the computer for the same reason. The factory 2 BAR MAP sensor is only capable of reading boost levels up to about 14 PSI (This number may not be totally accurate but very close), a 3 BAR MAP is able to read boost levels much higher, which is needed when adding bigger turbos, more boost and alcohol injection. It's a little more complicated but, this is probably all you need. For more in depth explanation, there are some very helpful and knowledgeable people on this board.

 

[pacecarta]

stock map sensor is a 2BAR, and it can read 2 BAR ... 1BAR vac to 1 BAR pressure ...BAR is metric equivalent for 1 atmosphere or in english measure 14.7psi so you can read ~15psi vac and 15psi pressure with it

and it has nothing to do with bigger turbos since the stock is plenty capable of running at over 15psi

the 2 bar map on a stock ecu isnt connected to the computer , its only function is to provide a signal for the indash boost gauge and can only read up to 15psi which was fine for the settings as the car left the factory ....installing a 3bar in its place will do nothing for performance ,it will make the gauge read incorrectly (if it reads correctly which most dont ) and will lighten your wallet by about 75 clams

3bar map sensor just adds 1BAR to its range to the pressure side so you could read boost to ~30psi (if you had a gauge calibrated for such)

now if you have alkycontrol alky injection the 3bar is used for reference to drive the alky pump faster or slower allowing for controlled spray up to ~30psi

if you have a power logger the 3bar allows logging boost to ~30psi

if you have an aftermarket ecm like fast, xfi , dfi ,maftpro or powerlogger and turbotweak SD which can run in speed density (no MAF based fueling) the 3bar map is needed to run over 15psi because the cars fueling will be controlled in part by the map sensor

 

[clusolynn]

Just tryin' to help!

I use to work mainly on Chryslers/Dodge, they used the MAP differently. Also, I was TOLD, that for my GEN II to work correctly, that I would need a MAP capable of reading boost higher than stock of 15 psi, this is where I got the BIGGER turbo thing, since mine is after market and was set at 20 psi with a mechanical boost controller, I ASSUMED, yes, I know what assume stands for; anyway, if I absolutely don't need a 3 BAR MAP for my GEN II set-up, please let me know. Thanks, John Lynn

 

[BenPutnam]

Thanks for the info. That is odd that the computer doesn't use it.

 

[TurboDave]

Thanks for the info. That is odd that the computer doesn't use it.

Not odd at all, since the original ECM's are MAF based.

 

[Razor]

Thanks for the info. That is odd that the computer doesn't use it.

Actually all digital dash Buicks didnt even come with a MAP sensor.

Works on 5 volts DC. 1.6 volts is zero PSI, 3.2 volts is 15 PSI. 4.8 volts is 30 PSI

Roughly

 

[pacecarta]

and no you dont need a map sensor for the gen 11, but having wideband helps tuning with that unit

 

[83ttypecooled]

Hi,
Just for information, GNX and TTA use three bar map sensors. The gauge is the only input,as stated before.

 

[Razor]

Hi,
Just for information, GNX and TTA use three bar map sensors. The gauge is the only input,as stated before.

Correction.. Only vehicle ever made by GM that uses the 3 bar is the 1989 TTA.

The GNX was a mechanical boost gauge. :wink:

 

[BenPutnam]

Not odd at all, since the original ECM's are MAF based.

It's odd that the original ECM's are only MAF based.

 

[TurboDave]

Not odd at all. Vast majority of all cars produced since the 80's are MAF based.

 

[BenPutnam]

What do the rest of them use the map sensor for then?

 

[Razor]

What do the rest of them use the map sensor for then?

Barometric adjustment to calculate for altitude. Newer GM cars use both MAP and MAF for different things.

The GN being a primitive computer didnt.

 

[Dr.drivability]

?

Is maf or map more accuratre???

 

[Razor]

Is maf or map more accuratre???

For what?