GM 3 Bar MAP Install

[NOMIEZVR4]

So I've got a MAP sensor on the way...I've been looking around for an install tutorial, didn't find one so thought I'd start a thread. Its got 3 wires, Power, GND and signal wire. Finding Power and GND shouldn't be an issue, but where to tap for the signal and more importantly, how do I hook it to my ECU harness so I can log boost? I'm assuming PIN 93...can someone fill in the details? :p

Thanks! I can take pictures when installing mine so others will have a guide to help in future installs :)

[llabmik2]

Just make sure you hook it up to a +5v not a +12v......i've seen it done.

[mjannusch]

You can get +5v off the TPS/sensor power wire (I believe it is a green wire with a yellow stripe), ground is any one of the grounds at the ECU, and if you've got a wire already on pin 92 (not 93 - that's set up for wideband input in Chrome) then cut it and splice the MAP output wire to the wire going into pin 92. Depending what harness you have, you might need to add a lead into pin 93's location.

Sorry I don't have more detail on the +5 power, I used the 0-5v output from my PLX Devices vac/boost sensor module so I didn't have to hook up +5v this time around.

I recommend that you put in the general GM sensor specs for voltage and pressure in Chrome, and then double-check it with some sort of an air source with a boost gauge hooked up that's known to be accurate - you may have to adjust the values a bit in Chrome to get it to match. Once it is set up, you should be good to go.

[kywhitelightning]

Use the MAF 5V source and GND. Send your signal to PIN 92. I installed mine under the fuse/relay box on the PS. There's a captured nut on the fuse box bracket that works perfectly to mount it. Once installed use a pressure pump to validate the readings through Evoscan. I amended mine a little because the defaults seemed to be off just a hair.

One other thing, I bought a cheap ebay knockoff earlier this year and it failed within a few months. First it leaked and then anytime I went into boost it would peg the log. Buyer beware. The real OE part numbered sensor hasn't let me down yet though.

This should be a great how to. Thanks Nomie!!

Jeff

[NOMIEZVR4]

wow, quick responses! Thanks guys!

Jeff I really wanna see my boost curve on VD!!..can't wait :D Thanks for the heads up...I actually purchased an EBAY unit(after reading online reviews) but I'll just keep it because the pigtail from GM is $30 anyways...so I'll just order a MAP sensor from NAPA..cross referenced the part number actually costs almost $100 less than the GM Dealer...I'll post all details here...Oh yeah...I forgot to mention...the EBAY Sensor I got comes with a 2 year warranty!...so I guess I'll hold off on getting the napa part for now..

http://www.ebay.com/itm/321237632879

Thats the link for the sensor I got in case anyone else is interested.

[kywhitelightning]

Yep, that's the cheapo I was referring to. Unfortunately the pigtail for the one I have now is different than the one shown in the image. It doesn't take much to get it to work (5 minutes and a jewelers screwdriver to knock off the aligning notches) but, they definitely are different. Here's the one I have now. It's even a little cheaper than the price you quoted from NAPA.

GM 3 Bar Map Sensor - Modern Automotive Performance (http://www.maperformance.com/gm-3-bar-map-sensor.html)

Jeff

[99 vr4]

You can get +5v off the TPS/sensor power wire (I believe it is a green wire with a yellow stripe), ground is any one of the grounds at the ECU, and if you've got a wire already on pin 92 (not 93 - that's set up for wideband input in Chrome) then cut it and splice the MAP output wire to the wire going into pin 92. Depending what harness you have, you might need to add a lead into pin 93's location.

Sorry I don't have more detail on the +5 power, I used the 0-5v output from my PLX Devices vac/boost sensor module so I didn't have to hook up +5v this time around.

I recommend that you put in the general GM sensor specs for voltage and pressure in Chrome, and then double-check it with some sort of an air source with a boost gauge hooked up that's known to be accurate - you may have to adjust the values a bit in Chrome to get it to match. Once it is set up, you should be good to go.


Use the MAF 5V source and GND. Send your signal to PIN 92. I installed mine under the fuse/relay box on the PS. There's a captured nut on the fuse box bracket that works perfectly to mount it. Once installed use a pressure pump to validate the readings through Evoscan. I amended mine a little because the defaults seemed to be off just a hair.

One other thing, I bought a cheap ebay knockoff earlier this year and it failed within a few months. First it leaked and then anytime I went into boost it would peg the log. Buyer beware. The real OE part numbered sensor hasn't let me down yet though.

This should be a great how to. Thanks Nomie!!

Jeff

In order to get accurate readings, you must hook the sensor up correctly. Unfortunately, everyone seems to think that you just need power and ground and you have a signal. This is not the case.

The sensor needs 5V DC. The sensor also needs a proper ground reference, as the sensor output is relative to this ground. Therefore ALL sensors share a SENSOR GROUND, this is NOT CHASSIS GROUND or BATTERY NEGATIVE!

To clarify, DO NOT HOOK ANY MAP SENSOR GROUND TO CHASSIS GROUND. THIS WILL SKEW THE OUTPUT!

In order to get correct readings, any MAP sensor must get voltage from pin 42 on the 98/99 ECU (pin 61/81 on the 91-97 ECU). This is +5V for the sensors. This is available at various points under the hood. Sensor ground is available from pin 49 on the 98/99 ECU (pin 72/92 on the 91-97 ECU). Again this is available at various points under the hood. The MAP sensor input is pin 92 on the 98/99 ECU (pin 74 on the 96-97 ECU, the only years with a factory MAP sensor).

The MAF +5v (pin 1 on the MAF - should be Green with Yellow Stripe) and Signal Ground (pin 5 on the MAF - should be a black wire) as Jeff mentioned above will work fine. You can also get it closer at the TPS: Pin 1 (again green with yellow) and Pin 4 (black wire).

All of the Clone PnP harnesses have a Yellow (+5v) and Green (+0v) pigtail along with the MAP sensor input pigtail to facilitate the addition of a MAP sensor.

Now for the TECHNICAL BLABBER:

In all vehicles, measuring voltage at different points around the vehicle will yield different voltages due to supply voltage losses due to wiring and ground losses due to vehicle construction. If you were to then measure those same voltages around the vehicle using the same ground point (like the battery negative terminal), you would see a completely different set of results, sometimes more than .1 volt! This is why ground kits help.

Now for most things, this is not an issue; Things like light bulbs, wiper motors, switches, etc. But for things like O2 sensors, throttle position sensors, MAF Sensors, and the MAP sensor, to name a few, which work on tenths (and sometime lower) of a voltage, changing the output from .4 to .5 volts IS significant. So in order to fix this issue, there is a separate ground for all of the sensors, which is referred to as signal ground. All reference systems in the car responsible for engine managements share this common ground which is NOT tied to chassis ground. In fact, if you measure the voltage on this line as referenced to chassis or battery ground, you will see that it is NOT 0.000V! But that is ok, because all of the systems are using this as the signal ground, so they are all in synch in relation to each other.

[NOMIEZVR4]

http://hhscott.com/93tmv/images/3BAR.gif

Is this correct? EDIT: YES
A-GND goes to pin 5 of MAF Harness
B-Signal goes to Pin 92 of ECU Harness
C-5V goes to Pin 1 of MAF Harness

That's all there is to it as far as the Hardware setup goes. I'll probably T the Line from the BOV and run it to the MAP Sensor.

[NOMIEZVR4]

Verified online...its OK. Map Sensor is wired in..Pictures to follow shortly.

Next Step is to figure out what settings need to be changed in EVOscan and ECUflash(if any?)

[NOMIEZVR4]

bump...

what has to be done in evoscan and ecuflash...? :) anyone got any ideas..

[kywhitelightning]

Under sensor scaling and pin 92 enter these values

Volts:
0
0.6274509803921569
1.137254901960784
1.607843137254902
3.882352941176471
4.921568627450981

PSI:
-14.7845
-9.02
-4.353499999999999
0.03850000000000264
20.07700000000001
29.41

In Evoscan I have this formula for MAP scaled
x*0.2745-19.1

Check the box in Evoscan then validate the readings with a pressure pump. If all the readings are off by say +1psi then consider changing the value in Evoscan. If the readings are all over the place both + and - then change the values in Ecuflash to match. As long as the actual pressure is the same as displayed pressure then you're good reguardless of how flaky the inputs look to both the logger and the tune.

Jeff

[Greg E]

Under sensor scaling and pin 92 enter these values

Volts:
0
0.6274509803921569
1.137254901960784
1.607843137254902
3.882352941176471
4.921568627450981

PSI:
-14.7845
-9.02
-4.353499999999999
0.03850000000000264
20.07700000000001
29.41

In Evoscan I have this formula for MAP scaled
x*0.2745-19.1

Check the box in Evoscan then validate the readings with a pressure pump. If all the readings are off by say +1psi then consider changing the value in Evoscan. If the readings are all over the place both + and - then change the values in Ecuflash to match. As long as the actual pressure is the same as displayed pressure then you're good reguardless of how flaky the inputs look to both the logger and the tune.

Jeff

Thank you Jeff!

To add to this, the reason there is a variance to the map sensor vs a real pressure gauge is due to 2 reasons:

*map sensors are absolute meaning they can't compensate for barometric pressure

*electrical varrances between different vehicle chassis.

I had actually started to collect data in order to come up with a calculation correction for Baro pressure but realized it was pointless because of the 2nd point. :(

[NOMIEZVR4]

Thank you sirs! :D

I'll test it today and post results.

[RealMcCoy]

Thank you Jeff!

*map sensors are absolute meaning they can't compensate for barometric pressure

I had actually started to collect data in order to come up with a calculation correction for Baro pressure but realized it was pointless because of the 2nd point. :(

I don't see the problem..? KOEO the MAP hands you a BARO reading. should be pretty easy to reference from there..?

[Greg E]

I don't see the problem..? KOEO the MAP hands you a BARO reading. should be pretty easy to reference from there..?

KOEO = Key on, Engine off??

I guess I could code a modifier which is updated when the engine rotation flag = 0 (engine not spinning). That would solve the eletrical and baro off set. Adds quite a bit of code though but it's not a bad idea. Especially for what I'm working on in the near future.

[99 vr4]

Thank you Jeff!

To add to this, the reason there is a variance to the map sensor vs a real pressure gauge is due to 2 reasons:

*map sensors are absolute meaning they can't compensate for barometric pressure

*electrical varrances between different vehicle chassis.

I had actually started to collect data in order to come up with a calculation correction for Baro pressure but realized it was pointless because of the 2nd point. :(

Point 2 is exactly why there is a sensor imposed voltage and sensor ground... The ecu tries to regulate this and take that variable away. Other wise none of the code would work between different cars...

Remember that all the important stuff, including the MAF, use the sensor ground reference. Now while the main signal is a frequency, there is a baro pressure and a temperature signal that are voltage based, and use the sensor voltage and sensor ground...

That being said, you should be able to code this, and AS LONG AS no one has used the sensor ground as chassis ground, things should be ok.

FYI, this is the reason I choose to have a sensor voltage and sensor ground pigtail on my harness with an extension harness with three wires to the MAP sensor... Less likely to hook up the map sensor wrong and less likely to be tempted to use the signal ground as a ground..

Brett

[Greg E]

Point 2 is exactly why there is a sensor imposed voltage and sensor ground... The ecu tries to regulate this and take that variable away. Other wise none of the code would work between different cars...

Remember that all the important stuff, including the MAF, use the sensor ground reference. Now while the main signal is a frequency, there is a baro pressure and a temperature signal that are voltage based, and use the sensor voltage and sensor ground...

That being said, you should be able to code this, and AS LONG AS no one has used the sensor ground as chassis ground, things should be ok.

FYI, this is the reason I choose to have a sensor voltage and sensor ground pigtail on my harness with an extension harness with three wires to the MAP sensor... Less likely to hook up the map sensor wrong and less likely to be tempted to use the signal ground as a ground..

Brett

We have had this conversation at least 6 times now. :p

So far my experience with running aftermarket sensors has been that some can offset all the other sensors. We already discussed this multiple times too. I haven't tried the GM MAP sensor to see if it does or not.

[99 vr4]

We have had this conversation at least 6 times now. :p

So far my experience with running aftermarket sensors has been that some can offset all the other sensors. We already discussed this multiple times too. I haven't tried the GM MAP sensor to see if it does or not.

Yes that was in regard to sending in a 0-5 v signal on an input expecting 0-1 v... causes unexpected offsets, mainly noticed on the O2 inputs.. Have you experienced this on the MAP sensor or Fuel Tank Pressure Differential sensor inputs? Probably not as they are designed for 0-5 v input....

AS LONG AS THE SENSOR DOES NOT EXCEED 5 volts, this should work.

;)

[Greg E]

Yes that was in regard to sending in a 0-5 v signal on an input expecting 0-1 v... causes unexpected offsets, mainly noticed on the O2 inputs.. Have you experienced this on the MAP sensor or Fuel Tank Pressure Differential sensor inputs? Probably not as they are designed for 0-5 v input....

AS LONG AS THE SENSOR DOES NOT EXCEED 5 volts, this should work.

;)

No I'm talking about other 5V inputs not the o2 inputs. Don't want to discuss it publicly because it'll cause hype but we have talked about it privately before. Remember out talk about how much power a sensor dumps onto ground?

[Chris@Rvengeperformance]

I used chassis ground for the gm map. Maybe it isn't the greatest thing to do, but at the end of the day I cared way more about my boost curve than the exact boost PSI I was running. It isn't like we are tuning SD with it.

[NOMIEZVR4]

Alrite...MAP is installed and tested, works great!

Here is a quick write up :) Thanks Jeff and Greg and everyone else for the help.

Here is the Sensor with the pigtail..
http://i.ebayimg.com/t/3-BAR-MAP-SENSOR-GM-STYLE-GMC-TRANS-AM-GRAND-NATIONAL-FIREBIRD-TURBO-BOOST-v1-/00/s/MTI4MFg3Njg=/z/MP8AAOxyiRlSbfTg/$(KGrHqZ,!pwFJeshk7BqBSbfTgd(Kg~~60_12.JPG

First thing I mounted the sensor...
http://i314.photobucket.com/albums/ll440/nomiezvr4/20131104_112246_zpsec88053c.jpg (http://s314.photobucket.com/user/nomiezvr4/media/20131104_112246_zpsec88053c.jpg.html)

Here is the harness...Yellow wire went to GND on MAF harness(Pin5 black wire) and Brown wire went to +5V on MAF harness(Pin1 green w/white stripe)..I extended the wires for the power and ground...:p
http://i314.photobucket.com/albums/ll440/nomiezvr4/20131104_112312_zps1e5f4a1b.jpg (http://s314.photobucket.com/user/nomiezvr4/media/20131104_112312_zps1e5f4a1b.jpg.html)

http://i314.photobucket.com/albums/ll440/nomiezvr4/20131104_134633_zpsb2f017e2.jpg (http://s314.photobucket.com/user/nomiezvr4/media/20131104_134633_zpsb2f017e2.jpg.html)

Pulled my harness out of the car and put a pin/wire in for #92 and put a spade on it for easy connect/disconnect(blue)..
http://i314.photobucket.com/albums/ll440/nomiezvr4/20131104_134622_zps86451bd0.jpg (http://s314.photobucket.com/user/nomiezvr4/media/20131104_134622_zps86451bd0.jpg.html)

Next I ran a wire from the ORANGE wire of the harness to Pin 92...(no picture)

Put the settings posted above in ECUFlash and the formula in EVOscan, Flashed the ROM, Put a vac line with a T to the boost gauge to verify readings were correct on the MAP sensor and Viola! Thanks for reading! :D

[familyMAN]

3 bar? Seems a little weak ;)

[NOMIEZVR4]

3 bar? Seems a little weak ;)

Heh...I won't need much more to take care of you from a 35 roll...;)

[familyMAN]

Since my "laggy" td05s actually spool up quicker than your 19ts, a 35 roll may not be what you want;)

Actually the GM 3 bar is probably perfect for your setup. Good choice and inexpensive. You finally get to log boost!

[NOMIEZVR4]

I hope the day actually comes when we actually run..haha

[familyMAN]

Me too!

[99 vr4]

Discovered recently that not all GM style 3 BAR MAP sensors share the same scaling. I will post more on this later next week with all of the correction factors for the various sensors.

[Jimvr4]

wow, quick responses! Thanks guys!

Jeff I really wanna see my boost curve on VD!!..can't wait :D Thanks for the heads up...I actually purchased an EBAY unit(after reading online reviews) but I'll just keep it because the pigtail from GM is $30 anyways...so I'll just order a MAP sensor from NAPA..cross referenced the part number actually costs almost $100 less than the GM Dealer...I'll post all details here...Oh yeah...I forgot to mention...the EBAY Sensor I got comes with a 2 year warranty!...so I guess I'll hold off on getting the napa part for now..

3 Bar Map Sensor GM Style GMC Trans Am Grand National Firebird Turbo Boost V1 | eBay (http://www.ebay.com/itm/321237632879)

Thats the link for the sensor I got in case anyone else is interested.

Just bought one of these on Ebay. For $30 it even comes with the pigtail. Now I'll be able to remove my AVC-R for good as I was only using it for a MAP sensor to log boost :)

3 BAR MAP SENSOR GM STYLE GMC TRANS AM GRAND NATIONAL FIREBIRD TURBO BOOST (http://www.ebay.com/itm/221433440920?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

[NOMIEZVR4]

Yep..thank God my sensor is still going strong! No issues

[Jimvr4]

Got the sensor. I'm thinking of mounting on the firewall since the boost tee is right there. Then extending the harness and running it down through the grommet with all 3 wires to the ECU connectors. I'll tap 5V (pin 42, sensor impressed voltage) , GND (pin 49, sensor ground) , and pin 92 right there.

[striker2]

I actually ran a vacuum line into the cabin and mounted the sensor to the ECU bracket and tapped into the ECU harness there. I happened to have a hard plastic vacuum line from a Taurus that had the perfect bends to run from the manifold right along the firewall and through the grommet on the passenger side.

[Zybrainn]

Got the sensor. I'm thinking of mounting on the firewall since the boost tee is right there. Then extending the harness and running it down through the grommet with all 3 wires to the ECU connectors. I'll tap 5V (pin 42, sensor impressed voltage) , GND (pin 49, sensor ground) , and pin 92 right there.

You can use the egrt wire if you want and there's a spot to tap into on the firewall. Details can be found in the below link.

3000GT/Stealth International Message Center (http://www.3si.org/forum/showthread.php?t=368791#/forumsite/20680/topics/368791)

[Jimvr4]

You can use the egrt wire if you want and there's a spot to tap into on the firewall. Details can be found in the below link.

3000GT/Stealth International Message Center (http://www.3si.org/forum/showthread.php?t=368791#/forumsite/20680/topics/368791)

No thanks :) I know exactly what I'm doing with those wires.

[kywhitelightning]

Just bought one of these on Ebay. For $30 it even comes with the pigtail. Now I'll be able to remove my AVC-R for good as I was only using it for a MAP sensor to log boost :)

3 BAR MAP SENSOR GM STYLE GMC TRANS AM GRAND NATIONAL FIREBIRD TURBO BOOST (http://www.ebay.com/itm/221433440920?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

Just a heads up on that sensor, pressure test it and pressure test it often!!!! I bought one of those and it leaked badly. Worst $30 I ever spent. I ponied up for the real sensor and all is well. Expect to pay $60-70 for a quality sensor.

This is the one I replaced the junk with. GM 3 Bar Map Sensor - MAPerformance (http://www.maperformance.com/gm-3-bar-map-sensor.html)

It doesn't come with a pigtail so you'll either need to purchase one or you'll need to slightly modify the junk ebay sensor's pigtail.

Jeff

[Greg E]

Just a heads up on that sensor, pressure test it and pressure test it often!!!! I bought one of those and it leaked badly. Worst $30 I ever spent. I ponied up for the real sensor and all is well. Expect to pay $60-70 for a quality sensor.

This is the one I replaced the junk with. GM 3 Bar Map Sensor - MAPerformance (http://www.maperformance.com/gm-3-bar-map-sensor.html)

It doesn't come with a pigtail so you'll either need to purchase one or you'll need to slightly modify the junk ebay sensor's pigtail.

Jeff

Huh. You're the 3rd person to report issues with that sensor leaking in the last couple weeks.

Good to know. I will steer people away from it.

[Chris@Rvengeperformance]

I think I got the delphi version from amazon, seems okay

http://www.amazon.com/gp/product/B001NZS9A4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

[99 vr4]

Huh. . I think i have the improved 3.0 bar on my website. .. With the connector. . $50... have had no problems with them

[Jimvr4]

Just a heads up on that sensor, pressure test it and pressure test it often!!!! I bought one of those and it leaked badly. Worst $30 I ever spent. I ponied up for the real sensor and all is well. Expect to pay $60-70 for a quality sensor.

This is the one I replaced the junk with. GM 3 Bar Map Sensor - MAPerformance (http://www.maperformance.com/gm-3-bar-map-sensor.html)

It doesn't come with a pigtail so you'll either need to purchase one or you'll need to slightly modify the junk ebay sensor's pigtail.

Jeff

Jeff, thanks for the heads up. I have a Mityvac 8500 so I will test it for both pressure and vacuum before installing.

[99 vr4]

Remember that not all MAP sensors measure vacuum.

[Greg E]

...and almost none of the map sensors are relative. They are mostly absolute.

[99 vr4]

Yes. . Of course i have a relative sensor on the site as well as a absolute