MAP sensor reading off? 1 or 2 bar
Thread Starter
Teching In
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From: Whidbey Island, WA
MAP sensor reading off? 1 or 2 bar I completed a swap using a LY6 engine , 4L80E trans, E38 pcm from a 08 3500 express into my 02 camaro.
My understanding is that the van would use a 1 bar map since it was N/A and based on research of the P/N 09359409 and the fact that the factory settings were linear 94.43 and offset 10.34 i believed it was a 1 bar map. Since im turbocharged now i knew i would need to upgrade to a 2 bar map at minimum.
I was getting 102 kpa with key on engine off on the VCM scanner at about 60kpa at idle to do some idle tuning which worked and pushed me more to believe it was a 1 bar map.
I wanted to do some road tuning and didnt want to chance getting into boost on a 1 bar map so i switched over to the 2bar os and installed a new map sensor P/N 12614970 which was suposed to be a 2 bar sensor with linear 200 and offset 10.34 settings and got 205kpa on the scanner with key on engine off.
So that led me to check the voltage on the new map which was 4.8v key on engine off. The original map was about 2.6v key on engine off which makes me believe i had a 2 bar in the first place.
Ive done about 20 hours looking around various forums and sites and accepted that the new map i bought is a 1 bar because of the 4.8v key on engine off and im out of that money but this brings the question.
Why would that map sensor show 100 kpa on the scanner key on engine off with 94.43 linear (5v) and 10.34 offset (0v) with 2.5 volts? Shouldnt it have shown around 55-65kpa at 2.5v with the linear and offset settings?
My understanding is that the van would use a 1 bar map since it was N/A and based on research of the P/N 09359409 and the fact that the factory settings were linear 94.43 and offset 10.34 i believed it was a 1 bar map. Since im turbocharged now i knew i would need to upgrade to a 2 bar map at minimum.
I was getting 102 kpa with key on engine off on the VCM scanner at about 60kpa at idle to do some idle tuning which worked and pushed me more to believe it was a 1 bar map.
I wanted to do some road tuning and didnt want to chance getting into boost on a 1 bar map so i switched over to the 2bar os and installed a new map sensor P/N 12614970 which was suposed to be a 2 bar sensor with linear 200 and offset 10.34 settings and got 205kpa on the scanner with key on engine off.
So that led me to check the voltage on the new map which was 4.8v key on engine off. The original map was about 2.6v key on engine off which makes me believe i had a 2 bar in the first place.
Ive done about 20 hours looking around various forums and sites and accepted that the new map i bought is a 1 bar because of the 4.8v key on engine off and im out of that money but this brings the question.
Why would that map sensor show 100 kpa on the scanner key on engine off with 94.43 linear (5v) and 10.34 offset (0v) with 2.5 volts? Shouldnt it have shown around 55-65kpa at 2.5v with the linear and offset settings?
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See links.
https://ls1tech.com/forums/forced-in...ap-sensor.html
https://forum.hptuners.com/showthrea...-MAP-KOEO-0kPa.
Based on link it's my understanding that with KOEO (key on engine off) you don't get a reading (zero). For example: my tuner kept arguing with me that my 2 bar map was defective and wouldn't put the car on the dyno until I replaced the map sensor. Since I have a 98 my OS had been converted to the HP Tuners custom OS for 98 only OS.
He was wrong, the 2 bar map sensor reads correctly with KOEO (key on engine on).
Make sure you have inserted the correct offsets into the tune. In my case I left the settings as they were in the HP OS for a 2 bar map.
https://ls1tech.com/forums/forced-in...ap-sensor.html
https://forum.hptuners.com/showthrea...-MAP-KOEO-0kPa.
Based on link it's my understanding that with KOEO (key on engine off) you don't get a reading (zero). For example: my tuner kept arguing with me that my 2 bar map was defective and wouldn't put the car on the dyno until I replaced the map sensor. Since I have a 98 my OS had been converted to the HP Tuners custom OS for 98 only OS.
He was wrong, the 2 bar map sensor reads correctly with KOEO (key on engine on).
Make sure you have inserted the correct offsets into the tune. In my case I left the settings as they were in the HP OS for a 2 bar map.
Last edited by dlandsvZ28; Dec 2, 2020 at 01:58 PM. Reason: edit content
Thread Starter
Teching In
Joined: Sep 2018
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From: Whidbey Island, WA
Thanks for the response. Ive seen where some people say they dont get a reading from the map on the scanner KOEO but i dont think im having that problem as the map gets power and the scanner picks up roughly 100-105 kpa KOEO. The question still remains. Why would a 2.5v KOEO map show correct kpa with 1 bar (94 linear, 10 offset) settings.
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Your first map sensor was a 1-bar.
KOEO values for anything above a 1-bar in HPT are irrelevant. The 3 bar OS won't even show a kpa reading until the engine is running.
Start the engine, and then see what kpa you're getting at idle.
KOEO values for anything above a 1-bar in HPT are irrelevant. The 3 bar OS won't even show a kpa reading until the engine is running.
Start the engine, and then see what kpa you're getting at idle.
Thread Starter
Teching In
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From: Whidbey Island, WA
I attempted to start the car on the 2 bar OS with both sensors. Got to about 500rpm attempting to start but it wouldnt start as it was just dumping fuel 100 plus ms injector pulse. Results were the same.
KOEO 205KPA.
500 rpm cranking 140 kpa.
KOEO 205KPA.
500 rpm cranking 140 kpa.
Thread Starter
Teching In
Joined: Sep 2018
Posts: 10
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From: Whidbey Island, WA
I attempted to start the car on the 2 bar OS with both sensors. Got to about 500rpm attempting to start but it wouldnt start as it was just dumping fuel 100 plus ms injector pulse. Results were the same.
KOEO 205KPA.
500 rpm cranking 140 kpa.
KOEO 205KPA.
500 rpm cranking 140 kpa.
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When you removed the stock map sensor and replaced with the new 2 bar sensor did you install correctly. IMO it's difficult to install the sensor if the intake is on the car. It's easy to think that the elect plug is completely in the female socket when in fact it is not completely attached to the sensor. I can guarantee the engine will NOT run or start correctly if the elec plugin is not completely connected.
On my LS6 intake, I had to shave off the tab on the 2 bar sensor in order to install the sensor. Since the 2 bar sensor is for a different vehicle and manifold it wouldn't fit on the fbody LS6/LS1 intake manifold. Since I had the intake off when I installed the sensor, it was obvious that I would have to shave off the tab in order to install the sensor. Not so obvious if the intake manifold is installed on the engine.
Some sensors contain the orange rubber grommet on the neck of the sensor when you purchase the sensor. Some do NOT and it is optional. You can use the grommet from the stock sensor if you carefully remove it without splitting the grommet. The sensor must have the grommet before installing.
KPA is intake engine manifold vacuum. I doubt seriously that when the engine is cranking that it is creating 140 KPA.
Link to identify map sensors
https://www.robietherobot.com/storm/mapsensor.htm
On my LS6 intake, I had to shave off the tab on the 2 bar sensor in order to install the sensor. Since the 2 bar sensor is for a different vehicle and manifold it wouldn't fit on the fbody LS6/LS1 intake manifold. Since I had the intake off when I installed the sensor, it was obvious that I would have to shave off the tab in order to install the sensor. Not so obvious if the intake manifold is installed on the engine.
Some sensors contain the orange rubber grommet on the neck of the sensor when you purchase the sensor. Some do NOT and it is optional. You can use the grommet from the stock sensor if you carefully remove it without splitting the grommet. The sensor must have the grommet before installing.
KPA is intake engine manifold vacuum. I doubt seriously that when the engine is cranking that it is creating 140 KPA.
Link to identify map sensors
https://www.robietherobot.com/storm/mapsensor.htm
Last edited by dlandsvZ28; Dec 3, 2020 at 08:43 AM. Reason: edit content
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You either have a faulty map sensor, have the wrong map sensor, or didn't enter the settings into HPT correctly.
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I don’t find any info that says the 12614970 is a 2 bar sensor.
GM made a sensor for the Cobalt SS that was a 2.5 bar, plug and play with your orig GM Camaro harness.
GM also makes a 3 bar for the LS9 that is excellent. Not plug and play, need a pig tail, and rewire.
Why did you put a later ECU in your Camaro? E38 harness would be wired just fine for the LS9 3 bar sensor.
pretty confusing!
GM made a sensor for the Cobalt SS that was a 2.5 bar, plug and play with your orig GM Camaro harness.
GM also makes a 3 bar for the LS9 that is excellent. Not plug and play, need a pig tail, and rewire.
Why did you put a later ECU in your Camaro? E38 harness would be wired just fine for the LS9 3 bar sensor.
pretty confusing!
Thread Starter
Teching In
Joined: Sep 2018
Posts: 10
Likes: 0
From: Whidbey Island, WA
I don’t find any info that says the 12614970 is a 2 bar sensor.
GM made a sensor for the Cobalt SS that was a 2.5 bar, plug and play with your orig GM Camaro harness.
GM also makes a 3 bar for the LS9 that is excellent. Not plug and play, need a pig tail, and rewire.
Why did you put a later ECU in your Camaro? E38 harness would be wired just fine for the LS9 3 bar sensor.
pretty confusing!
GM made a sensor for the Cobalt SS that was a 2.5 bar, plug and play with your orig GM Camaro harness.
GM also makes a 3 bar for the LS9 that is excellent. Not plug and play, need a pig tail, and rewire.
Why did you put a later ECU in your Camaro? E38 harness would be wired just fine for the LS9 3 bar sensor.
pretty confusing!
I have a 12615136 2 bar sensor coming from the dealership either later today or tomorrow morning. Will post updates once its installed.
Thread Starter
Teching In
Joined: Sep 2018
Posts: 10
Likes: 0
From: Whidbey Island, WA
When you removed the stock map sensor and replaced with the new 2 bar sensor did you install correctly. IMO it's difficult to install the sensor if the intake is on the car. It's easy to think that the elect plug is completely in the female socket when in fact it is not completely attached to the sensor. I can guarantee the engine will NOT run or start correctly if the elec plugin is not completely connected.
On my LS6 intake, I had to shave off the tab on the 2 bar sensor in order to install the sensor. Since the 2 bar sensor is for a different vehicle and manifold it wouldn't fit on the fbody LS6/LS1 intake manifold. Since I had the intake off when I installed the sensor, it was obvious that I would have to shave off the tab in order to install the sensor. Not so obvious if the intake manifold is installed on the engine.
Some sensors contain the orange rubber grommet on the neck of the sensor when you purchase the sensor. Some do NOT and it is optional. You can use the grommet from the stock sensor if you carefully remove it without splitting the grommet. The sensor must have the grommet before installing.
KPA is intake engine manifold vacuum. I doubt seriously that when the engine is cranking that it is creating 140 KPA.
Link to identify map sensors
https://www.robietherobot.com/storm/mapsensor.htm
On my LS6 intake, I had to shave off the tab on the 2 bar sensor in order to install the sensor. Since the 2 bar sensor is for a different vehicle and manifold it wouldn't fit on the fbody LS6/LS1 intake manifold. Since I had the intake off when I installed the sensor, it was obvious that I would have to shave off the tab in order to install the sensor. Not so obvious if the intake manifold is installed on the engine.
Some sensors contain the orange rubber grommet on the neck of the sensor when you purchase the sensor. Some do NOT and it is optional. You can use the grommet from the stock sensor if you carefully remove it without splitting the grommet. The sensor must have the grommet before installing.
KPA is intake engine manifold vacuum. I doubt seriously that when the engine is cranking that it is creating 140 KPA.
Link to identify map sensors
https://www.robietherobot.com/storm/mapsensor.htm
Ive visited the website you posted before i created the thread. The voltage chart on the site for 2 bar sensors is what started my confusion as why a 1 bar sensor would put out 2.5v KOEO and show 100kpa on the scanner.
It was a V6 with blown engine and i went the route of swapping the complete drivetrain LY6/4L80E and E38 ecu from the 3500 van i bought.
I have a 12615136 2 bar sensor coming from the dealership either later today or tomorrow morning. Will post updates once its installed.
I have a 12615136 2 bar sensor coming from the dealership either later today or tomorrow morning. Will post updates once its installed.
The sensor you ordered is the Cobalt SS sensor. Plug and play with the Gen 3 harness. Not sure about the Gen 4. You might need a pigtail and a small amount of re-wiring.
Thread Starter
Teching In
Joined: Sep 2018
Posts: 10
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From: Whidbey Island, WA
The 12615136 is definitely a 2 bar sensor. Scaled it to 200 linear and 8 offset. It did not come with the orange seal but i was able to transfer it over from my old 1 bar sensor and it plugged right in to my e38 harness wiring. I got 103 kpa KOEO and it seemed to give accurate reading during startup and idle. Still needs lots of idle tuning but so far so good. Thanks to everybody for all the inputs.
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Link contains pics of the LS3 and L76 intake manifolds. It appears there is difference in how to secure the map sensor to the intake. One is secured with a bolt, the other is secured with tabbed clip securing the sensor.
https://ls1tech.com/forums/pontiac-g...manifolds.html
This a pic of the 2 bar sensor PN 12615136. It does not have a mounting hole to secure it to the manifold but it is tabbed on both sides.
https://www.summitracing.com/parts/ado-213-1631
So dependent on which manifold you have IMO will determine how to secure the map sensor. You do not want the map sensor to blow out under boost if it is not secured.
Some use a clamp like this to secure it to the manifold. You might have to make your own clamp/bracket.
https://www.ebay.com/i/303511103480?...IaAmP0EALw_wcB
https://ls1tech.com/forums/pontiac-g...manifolds.html
This a pic of the 2 bar sensor PN 12615136. It does not have a mounting hole to secure it to the manifold but it is tabbed on both sides.
https://www.summitracing.com/parts/ado-213-1631
So dependent on which manifold you have IMO will determine how to secure the map sensor. You do not want the map sensor to blow out under boost if it is not secured.
Some use a clamp like this to secure it to the manifold. You might have to make your own clamp/bracket.
https://www.ebay.com/i/303511103480?...IaAmP0EALw_wcB
Last edited by dlandsvZ28; Dec 4, 2020 at 11:46 PM. Reason: edit content