GM MAP sensor install

BIGGSIE · 04-26-2004, 12:43 PM

undefined Well I finally got around to installing my GM MAP sensor so I decided to do a small write up. The reason for this mod is to give the SAFC a boost related input instead of an input from the TPS. I will use an example I read somwhere else, say you are in third gear at 2500 RPM, you mash the gas and the SAFC sees 100% throttle position and starts to dump fuel, problem is your turbo has not spooled up yet and you don't need the extra fuel untill you reach full boost so your car has lag for a second or two. Another example is if you are crusing on the highway and you come to a hill your boost will start to rise due to the increased load but the SAFC will not compensate for this. Here is how you can trick the SAFC.

1.) Purchase: GM 3 bar MAP sensor (part # 12223861)
MAP sensor plug pig tail (NAPA)
Wire
Shrink wrap connectors

2.) Mount sensor under hood in a safe place. (Firewall)

3.) Wire plug to vehicle. Sensor and plug are labeled A, B, C, A=Ground, B=Output signal, C=5v power. Find a good ground (Neg. battery terminal) run wire to pin A. Find a steady 5v power supply (TPS harness) and wire to pin C. Run last wire from pin B through firewall near SAFC harness.

4.) Remove throttle signal wire (gray) from ECU harness and solder to the wire you just ran into the car. Make sure to protect all connections with shrink wrap.

5.) Run a vaccum hose from the sensor to a vaccum/boost sorce from the engine.

6.) Turn key on (engine off) and monitor throttle % on SAFC, set your low throttle point to that %. (mine was 22.9%) Now start engine and monitor %, should read 00.0%. If you are properly tuned then do a pull at your desired boost level and see what % you get, set your hi throttle point to just below that %. Now you can fine tune from there. You should notice a smooth onset of power, a little less lag, better partial throttle driving, and possibly batter gas milage.

I am sure there are different ways to set your throttle points but I haven't had time to play with it too much yet. If anyone has any comments or corrections let me know. Here are some pics of the install.

kpt4321 · 04-26-2004, 01:48 PM

http://www.2gnt.com/www/corbin/foolafc.html

Scrymerr · 09-17-2005, 09:41 PM

Can anyone tell me how accurate the GM unit is as compared to the more expensive AEM ones?

MNGSX · 09-17-2005, 09:50 PM

AEM just sells GM ones.

GM has one model called a "high accuracy" model...

Scrymerr · 09-17-2005, 09:57 PM

http://cgi.ebay.com/ebaymotors/3-Bar...spagenameZWDVW

http://cgi.ebay.com/1g-2g-DSM-EAGLE-...QQcmdZViewItem

I was under the impression the AEM ones were different as they use a 1/8" NPT fitting instead of the plastic nipple like the GM. I am looking what sensor to get to log boost on my GST using DSMlink.

MNGSX · 09-17-2005, 10:23 PM

Other than that its the same sensor.
Atleast the same as some GM sensors.

I know that GM had one that was the high accuracy model..

GM does'nt make them.. Another company... Like

did'nt make the denso fuel pump.. AEM just orders them to their specs with the NPT...

Scrymerr · 09-17-2005, 10:25 PM

Well, that helped a lot, thank you. I guess I will go ahead and buy a GM 3bar map sensor and call it a day.

Omega · 09-22-2005, 09:54 AM

FYI: The map sensor has to be mounted with the nipple facing down.

Why not just tap into the existing MAP sensor in the manifold?

hakcenter · 09-22-2005, 11:54 AM

Quote:

Originally Posted by MNGSX

Other than that its the same sensor.
Atleast the same as some GM sensors.

I know that GM had one that was the high accuracy model..

GM does'nt make them.. Another company... Like

did'nt make the denso fuel pump.. AEM just orders them to their specs with the NPT...

Well AEM is practically the only 'manufacturer' of map sensors past 3bar.

Remember, that on your bars, 1 bar is for vacuum, and the left overs is for positive pressure.

A 3bar map sensor will only read up to 29~psi (2bars).

lewroe59 · 09-22-2005, 08:28 PM

thats awesome. I've never heard of this...

MNGSX · 09-22-2005, 08:44 PM

GM Map sensor identification...

http://www.diy-efi.org/gmecm/compone...o/sensors.html

http://www.robietherobot.com/storm/mapsensor.htm

I believe that on the AEM 5bar and 3.5bar (have seen 4 too) the actuall MFG is bosch...

On the smaller range ones its the same MFG as GM........... Delphi

MNGSX · 09-22-2005, 08:51 PM

Quote:

Originally Posted by Omega

FYI: The map sensor has to be mounted with the nipple facing down.

Why not just tap into the existing MAP sensor in the manifold?

FYI

1. With a GM Map it does'nt matter which way the body points...

2. First gen cars dont have a MAP.. Neither do 2nd gens.

3. Second gens have a MDP or a manifold differential pressure sensor which the ECU normally just uses to check EGR operation. Therefore accuracy was'nt too important to them.

Scrymerr · 09-22-2005, 10:10 PM

Well, should I just shell out $140 and get an AEM 5bar, use my AVC-R sensor, or get a GM one. I just need to log boost with DSMlink.

MNGSX · 09-22-2005, 10:29 PM

A GM 3bar would log to ~30psi..

Need more?

I would get a Bosch 5 bar and cut out the middle man..

Honestly you could do a grainger map sensor... Just get something in the Bar range you need with a 0-5v output...

espinelli · 09-26-2005, 08:11 PM

I was under the impression that AEM gets thier map sensors from SSI. I forget who thier previous supplier was.

espinelli · 09-26-2005, 08:18 PM

Pic of my AEM 3.5bar sensor ...

Omega · 09-27-2005, 06:09 AM

I knew it was a pressure sensor of sorts, just couldn't remember why we couldn't use it.

There is a huge post on a f-body site about the position. Even in the instruction manual for the sensor it says that it must point down. The conclusion was so that moisture doesn't pool inside and cause failure. You can mount it anywhere, it won't bother me

With the GM 2 bar (12223861) you will also need the new connector: 15305891