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-   -   gm map sensor for high boost? (https://www.homemadeturbo.com/engine-management-10/gm-map-sensor-high-boost-8483/)

turboboy 08-11-2003 11:41 AM
gm map sensor for high boost?
 
ok guys i need some help. I ran 13psi with a stock map sensor and am wondering how i would go about switching to a different map to run more. Im thinking this would require some changes in my ecu, but im obd2. Im wondering if there is a way around this, possbly a resistor on it or something, i have no idea. This ecu ---- isnt my thing.

TurboEF9 08-11-2003 11:53 AM
Re:gm map sensor for high boost?
 
Once the correct GM MAP sensor is found, you just have to splice it in. The output is the exact same as the Honda MAP sensor, only the internal calibration is different. Basically, it still uses the 0-5v that Honda uses, but will increment differently.

Recurving your fuel and ignition MAPs will also be required.

Now, as for the "correct" MAP sensor to use? There has been some posts about that.. Might try the GhD sticky post. I believe I asked the question there and got a reponse, I just don't remember off the top of my head.

turboboy 08-11-2003 11:56 AM
Re:gm map sensor for high boost?
 
ok then i have another question... being that i cant change my ignition maps right now, is there a way to get a map sensor to support more boost without doing so?

TurboEF9 08-11-2003 12:06 PM
Re:gm map sensor for high boost?
 
Nope, it's a hardware limitation only corrected by replacement.

Chacko 08-11-2003 12:32 PM
Re:gm map sensor for high boost?
 
If you want to run 13 psi daily and keep your car reliable invest in a fuel management system. Hondata can be used in congolmeration with the GM 3 Bar Map sensor.

88crxSi 08-11-2003 12:34 PM
Re:gm map sensor for high boost?
 
ya man.. i think when u get up that high its time for hondata w/ ob2. maybe uberteg?

turboboy 08-11-2003 01:11 PM
Re:gm map sensor for high boost?
 
what im saying is can i run a gm map sensor without messing with the ecu, and what fuel corrections would be necessary say if i stayed at the same boost (what would the correction difference be?)

TurboEF9 08-11-2003 01:17 PM
Re:gm map sensor for high boost?
 
You can keep the same amount of boost with a higher rated MAP sensor, but your fuel and ignition tables will be off. They would need to be retuned. You will run lean because the signal output of the GM MAP sensor is scaled further than that of a Honda MAP sensor. This is the reason you can run more boost within the same voltage range 0-5v..

turboboy 08-12-2003 01:38 AM
Re:gm map sensor for high boost?
 
so if i add more fuel with the smc and increase the rate of the fmu (im going to run an fmu again too)....it should work in theory right? What would happen with the stock map above with more boost?...will it just cut out or what, ive never gone above 13.

And chacko, i was running 13 psi daily before, and the motor never blew.

ZexRex 08-12-2003 02:12 AM
Re:gm map sensor for high boost?
 
all a bigger map sensor does is send a different signal

example:
like if you have a 1 bar sensor at 1 bar it puts out 5v
if you have a 2 bar sensor at 1 bar it will put out 2.5v and a 3 bar will put out 1.66v at 1 bar.

all it does is change the boost levels that are across the top of the graph in your zdyne/ghettodyne software. you still have just as many squares to enter values for timing / fuel. basically it makes the signal less precise to fit in more boost. (does that make sense?)

as far as using an afc it prob could be done but im too tired to tell you how to do it besides go on a dyno with a wideband.

ShadowRex 08-12-2003 02:26 AM
Re:gm map sensor for high boost?
 
Hey I understand that See like this with a honda at 1 bar say yer at 9.62 (pm7 mugen bin) now say you want to hook up a gm 3 bar at 1 bar it sees 1.66v which on a honda would be about (---- math fart) 1/3rd so not only would you be lean you would be at about 24-25hg which i do not know that yer car would idle that lean.

Mind you this is all based off of 500rpm.

did i confuse myself???? ::)

TurboEF9 08-12-2003 09:19 AM
Re:gm map sensor for high boost?
 
Originally Posted by ZexRex
all a bigger map sensor does is send a different signal
Actually, it sends the same voltage (0-5v) but it's scaled differently. Say at 3.0 volts on a stock Honda MAP sensor, you're at ~1.3psi, on a GM MAP sensor at 3.0 volts you would be at ~21psi. Why? Because voltage increments are smaller with a GM 3bar MAP.

all it does is change the boost levels that are across the top of the graph in your zdyne/ghettodyne software.
And this is the most common misconception. Your fuel and ignition tables do not change. Using a different MAP sensor with a scaled voltage is similar to using an AFC (which also scales your voltage). Your fuel and ignition table column, and row increments stay exactly the same. You're just not going be using them in the same increments that you normally do. Which is why you need to retune them.

ShadowRex 08-12-2003 03:23 PM
Re:gm map sensor for high boost?
 
ok so Im right?

TurboEF9 08-13-2003 11:08 AM
Re:gm map sensor for high boost?
 
Originally Posted by ShadowRex
ok so Im right?
Heh, ya. ;)


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