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View Full Version : How to: Install GM MAP sensor



Matz
07-15-2006, 10:04 PM
This installation isn't exactly how-to worthy, but it'll get me one post closer to the 4000 mark.* :lol:

Here's a brief overview of what is involved (http://evo8.initialdproject.com/HowToInstallGMMAP/GM MAP installation overview.mpg)

I really wanted to install a pressure sensor so that I could log boost with the ECU+.* I decided on the GM MAP sensor, which you can buy from gmpartsdirect.com.

Parts needed:
(1) GM 3 bar MAP sensor - P/N 12223861
(1) MAP sensor connector - P/N 15305891
(3) rolls of 14AWG wire from Home Depot.* I like the colors red, black, and yellow (+5V, GND, signal, respectively)
(1) snap connector from Radio Shack
4' of 1/4" shrink tube
6" of 4mm ID silicone hose (you may need more if you're not teeing off another line, or don't have a boost gauge already installed
5/32" tee fitting
solder
soldering iron
electrical tape
zip ties
fish tape

Step 1: Zip tie down the MAP sensor and put on the silicone vacuum hose

http://evo8.initialdproject.com/HowToInstallGMMAP/mounting location.jpg;
http://evo8.initialdproject.com/HowToInstallGMMAP/closeup of sensor.jpg

Step 2: Cut existing hose, if available

http://evo8.initialdproject.com/HowToInstallGMMAP/cut existing hose.jpg

Step 3: Plug in pre-wired connector

http://evo8.initialdproject.com/HowToInstallGMMAP/connected.jpg

Step 4: Insert tee fitting

http://evo8.initialdproject.com/HowToInstallGMMAP/insert tee.jpg

Step 5: Connect 6" piece to tee fitting

http://evo8.initialdproject.com/HowToInstallGMMAP/all connected.jpg

Step 6: Route the wires toward the firewall.* Be sure that you route carefully and don't loop the wires around random things

http://evo8.initialdproject.com/HowToInstallGMMAP/careful routing.jpg

Step 7: Tape the three wires to the end of the fish tape.* The fish tape is the best thing ever for routing wires in your car!

http://evo8.initialdproject.com/HowToInstallGMMAP/fish tape.jpg
http://evo8.initialdproject.com/HowToInstallGMMAP/fish tape 2.jpg

Sometimes it's tough to get the fish tape through the hole... if this is the only set of wires that you're running through the firewall, you shouldn't have a problem.* I had previously installed my EGT, oil temp, and water temp senders, so I had to use my left hand to guide the fish tape through:

http://evo8.initialdproject.com/HowToInstallGMMAP/left hand helps.jpg

This is where the wires come out -- the hole is on the passenger side behind the glove box:

http://evo8.initialdproject.com/HowToInstallGMMAP/passenger side view.jpg
http://evo8.initialdproject.com/HowToInstallGMMAP/wires are through.jpg

Step 8: Put in a service loop!* You never know when something will go wrong and you may need more wire later.

http://evo8.initialdproject.com/HowToInstallGMMAP/service loop.jpg

Step 9: Solder the ends of the wires -- One is the yellow ECU+ MAP sensor input, and the other is obviously from the MAP sensor that you just ran through the firewall

http://evo8.initialdproject.com/HowToInstallGMMAP/solder1.jpg
http://evo8.initialdproject.com/HowToInstallGMMAP/solder2.jpg

Step 10: Connect your snap connectors to the two wires.* The convention is that the source of a signal is always female, and the sink is always male.

http://evo8.initialdproject.com/HowToInstallGMMAP/snap connectors.jpg
http://evo8.initialdproject.com/HowToInstallGMMAP/map signal connected.jpg

Step 11: No pics for this step, but it just involves hooking up +5V (red) and ground (black).* You'll have to splice into the ECU harness.* I used pin 81 for the red wire, and pin 92 for the black wire.

I haven't tested my sensor yet, but I plan to in a few minutes... can't wait!* :thumbsup:

wilson1
07-15-2006, 10:28 PM
so let us know if it works or not.

Matz
07-15-2006, 10:40 PM
so let us know if it works or not.


Going out right now. :)

wilson1
07-15-2006, 10:43 PM
sounds good!

Matz
07-15-2006, 10:51 PM
w00t!

http://evo8.initialdproject.com/HowToInstallGMMAP/it works.gif

Surprisingly enough, the readings are pretty close to what I was trying to hit on my GReddy boost gauge.

SJCoruja
07-16-2006, 12:18 AM
Damn you...again. :lol:

Thanks for the how-to...going to be needing it soon.

KareBearPowa
07-16-2006, 12:26 AM
Nice!

AreSTG
07-16-2006, 10:26 AM
you rock dude

Matz
07-16-2006, 11:40 AM
you rock dude


Hope that helps ya out! Let me know if you have any questions.

MarkSAE
07-16-2006, 12:18 PM
Nice writeup Dave! I have one concern about the way you've mounted the MAP sensor. It looks like you have it zip tied to the power steering line. For normal street driving, that line probably wouldn't get too hot. But at the track, that fluid can really heat up along w/ the aluminum line that you've mounted your sensor to. I don't think you want that heat going into your sensor.

Matz
07-16-2006, 03:02 PM
Nice writeup Dave! I have one concern about the way you've mounted the MAP sensor. It looks like you have it zip tied to the power steering line. For normal street driving, that line probably wouldn't get too hot. But at the track, that fluid can really heat up along w/ the aluminum line that you've mounted your sensor to. I don't think you want that heat going into your sensor.


Awesome point, and you are totally correct. I plan to make a bracket that goes off of the power steering reservoir so it won't be zip tied to the line anymore. However, I won't be able to do it before the autox next weekend. Any idea where else I could put it? Thanks!

AreSTG
07-16-2006, 04:51 PM
Nice writeup Dave! I have one concern about the way you've mounted the MAP sensor. It looks like you have it zip tied to the power steering line. For normal street driving, that line probably wouldn't get too hot. But at the track, that fluid can really heat up along w/ the aluminum line that you've mounted your sensor to. I don't think you want that heat going into your sensor.


Awesome point, and you are totally correct. I plan to make a bracket that goes off of the power steering reservoir so it won't be zip tied to the line anymore. However, I won't be able to do it before the autox next weekend. Any idea where else I could put it? Thanks!


hmm since your boost guage is inside the car, theres a vacuum line inside the firwall, couldnt you just T it on the inside of the firewall?

MarkSAE
07-16-2006, 05:28 PM
Awesome point, and you are totally correct. I plan to make a bracket that goes off of the power steering reservoir so it won't be zip tied to the line anymore. However, I won't be able to do it before the autox next weekend. Any idea where else I could put it? Thanks!


Your sensor should be fine for an auto-x. But you should check the line temperatures in between runs just in case. I would try to mount that sensor along the firewall. There are a few bolts you can use there.

AreSTG
07-16-2006, 05:29 PM
im wondering y it needs to be in the engine bay? simply for quicker response?

Matz
07-16-2006, 05:46 PM
Awesome point, and you are totally correct. I plan to make a bracket that goes off of the power steering reservoir so it won't be zip tied to the line anymore. However, I won't be able to do it before the autox next weekend. Any idea where else I could put it? Thanks!


Your sensor should be fine for an auto-x. But you should check the line temperatures in between runs just in case. I would try to mount that sensor along the firewall. There are a few bolts you can use there.


Ok, thanks!

Matz
07-16-2006, 05:47 PM
im wondering y it needs to be in the engine bay? simply for quicker response?


Yup, and so it's closer to the existing boost sensor. I could have routed one line into the car and hooked up both sensors there, but then that would have been a little extra work.

AreSTG
07-16-2006, 06:44 PM
im wondering y it needs to be in the engine bay? simply for quicker response?


Yup, and so it's closer to the existing boost sensor. I could have routed one line into the car and hooked up both sensors there, but then that would have been a little extra work.


forgive me for not fully understanding...

you want it near the existing boost sensor so the readings you get from the gm map sensor most accuratly represent what the ECU is seeing?

but that raises another question: if theres an existing boost sensor(map i assume?) why do we need th gm sensor for ECU+? and at the sae time i thought we had a MAF, meaning we dont have an actual boost sensor(map).

Something i just said doesnt make sense im sure, so please inform me how this works :)

MarkSAE
07-16-2006, 08:55 PM
We have a stock MAP sensor that's used for the EGR system. It's bolted right on the top of our stock intake manifolds. However, that sensor only reads from 0-1 bar. Since our cars run more than 1 bar of boost, we need a sensor that reads higher to monitor boost.

Matz
07-16-2006, 08:57 PM
im wondering y it needs to be in the engine bay? simply for quicker response?


Yup, and so it's closer to the existing boost sensor. I could have routed one line into the car and hooked up both sensors there, but then that would have been a little extra work.


forgive me for not fully understanding...

you want it near the existing boost sensor so the readings you get from the gm map sensor most accuratly represent what the ECU is seeing?

but that raises another question: if theres an existing boost sensor(map i assume?) why do we need th gm sensor for ECU+? and at the sae time i thought we had a MAF, meaning we dont have an actual boost sensor(map).

Something i just said doesnt make sense im sure, so please inform me how this works :)


The other boost sensor I'm referring to is the GReddy warning gauge that I installed previously. I just thought it would be nice if the two sensors were the same distance from the source so they would respond similarly.

So the only reason why I have the GM MAP is because the GReddy boost gauge doesn't have an aux out, and therefore the ECU+ needs another source. You're right that we have a MAF, which I would think is best because it automatically gives the ECU the air mass, rather than having to calculate it from various ambient conditions.

Matz
07-16-2006, 08:58 PM
We have a stock MAP sensor that's used for the EGR system. It's bolted right on the top of our stock intake manifolds. However, that sensor only reads from 0-1 bar. Since our cars run more than 1 bar of boost, we need a sensor that reads higher to monitor boost.


Cool, I did not know that.

KareBearPowa
07-16-2006, 08:59 PM
Which is why boost is NOT the only thing the ECU goes off of to calculate load.

AreSTG
07-17-2006, 09:40 AM
so Matz, if you installed your's to be similar to the Greddy, then for me, T'ing off of the line under my dash would be the best idea.

My point being, the ECU+ will recieve a reading most similar to my EBC which is in front of my shifter. I mean, the EBC is controlling my boost, directly affecting the engine, so getting a quicker reading from the engine bay would show a different reading on ECU+ than my EBC was reading at the same moment.

Or is it just simply more important for the ECU+ to get the quickest most accurate reading at any given moment than to reflect what my EBC is responding to when controlling boost?

Matz
07-17-2006, 11:17 AM
Tim, in either case, you may get different values anyway. I've read posts showing how the GM MAP (and any other MAP sensor for that matter) differs in reading from a variety of boost gauges. I would just install it under your dash, then, since it'll save you time on the installation.

dus10
09-20-2006, 11:06 AM
I just bought an Innovate LMA-3 data logger that has a built in MAP sensor for reading boost. In the instructions it says to find a boost/vaccumn source behind the throttle body in order to use MAP. It says that MAP is more accurate at reading boost than MAF. So where's the best spot to tap into?

Matz
09-20-2006, 12:51 PM
I just bought an Innovate LMA-3 data logger that has a built in MAP sensor for reading boost. In the instructions it says to find a boost/vaccumn source behind the throttle body in order to use MAP. It says that MAP is more accurate at reading boost than MAF. So where's the best spot to tap into?


I may be confused, but I always thought that the MAP was used to measure air pressure, and the MAF is used to measure air flow.

Anyhow, you tap into a hose coming out of the intake manifold.

dus10
09-20-2006, 03:48 PM
This is what INNOVATE says about it:

The LMA-3 has a built in MAP sensor. To use it, connect a small ¼” hose between a
vacuum/boost connection AFTER the throttle body and the LMA-3 MAP input port.
It should be connected after the throttle body because the lowest pressure that can be measured
before the throttle body is atmospheric pressure (discounting some pressure losses from the
intake tract before the throttle body).
MAP stands for Manifold Absolute Pressure. This means that the sensor measures pressure
referenced to absolute vacuum, not atmospheric pressure like many vacuum and boost gauges.
Engine parameters like fueling, ignition timing, compressor efficiency and so on are dependent on
the MASS of air (in pounds per cubic foot or kg per cubic meter) entering the engine. As air is a
gas, it’s mass is dependent on it’s ABSOLUTE pressure, referenced to absolute vaccuum and it’s
temperature.
Most vaccuum and boost gauges are gauge pressure sensors. A gauge pressure sensor
measures the difference to atmospheric pressure, not the absolute pressure. So, without knowing
atmospheric pressure at the point where the sensor gets it from, the actual air-mass entering the
engine can’t be measured. Because the atmospheric pressure changes with altitude and weather,
the gauge pressures are not a precise metric. This is specially problematic for boost pressure
sensors, because their atmospheric reference source comes typically from inside the cabin or
engine compartment. The atmospheric pressure there can change with speed from aerodynamic
effects (ram pressure).

Matz
02-27-2007, 10:45 AM
From MarkSAE:

He mounted his GM MAP in a much better place IMO. It's more stealthy, and it also doesn't sit on top of a hot pipe like mine does. :shock:

http://i91.photobucket.com/albums/k290/marksae/My%20Evo/GM%203-bar%20MAP%20Sensor/IMG_3159.jpg

The only thing I might add is some rubber tubing around the tee connector. Nice, Mark!