popeye55 Posted August 17, 2006 Report Share Posted August 17, 2006 I am trying to learn about all the pcm stuff. i cannont figure out what it means by a MAP sensor that is 1,2,or 3 bar? can someone dumb it down for me please. Link to comment Share on other sites More sharing options...
zippy Posted August 17, 2006 Report Share Posted August 17, 2006 This is referring to what pressure level the sensor reads to. A 1 bar map will read to about .7psi of boost, a 2 bar map will read to about 15 psi of boost, and a 3 bar map will read to about 30psi of boost. Link to comment Share on other sites More sharing options...
popeye55 Posted August 17, 2006 Author Report Share Posted August 17, 2006 that makes sence.. thanks for the clarification Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted August 17, 2006 Report Share Posted August 17, 2006 1 bar reads 1 atmosphere of pressure, which is to say -14.7psi of vacuum to 0.0psia (static sea level amtospheric pressure). 2 bar reads 2 atmospheres, so -14.7psi to 14.7psi (1 bar of vacuum, 1 bar of boost) 3 bar reads 3 atmospheres, so -14.7psi to 29.4psi (1 bar of vac, 2 bars of boost) Given the nature of a 1 bar sensor it is most suited to NA applications. Link to comment Share on other sites More sharing options...
misterp Posted August 17, 2006 Report Share Posted August 17, 2006 Aren't the 2-bar half the resolution of the 1-bar? Or are they the same resolution but you must have a custom PCM OS (with tables twice as big)? Mr. P. Link to comment Share on other sites More sharing options...
popeye55 Posted August 18, 2006 Author Report Share Posted August 18, 2006 oh damn...i was following unit that last post so what is the OS? Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted August 18, 2006 Report Share Posted August 18, 2006 Aren't the 2-bar half the resolution of the 1-bar? Or are they the same resolution but you must have a custom PCM OS (with tables twice as big)? Mr. P. <{POST_SNAPBACK}> Bingo. 2 or 3 bar MAP requires a custom OS. Link to comment Share on other sites More sharing options...
misterp Posted August 18, 2006 Report Share Posted August 18, 2006 oh damn...i was following unit that last post so what is the OS? Sorry for the geek-speak; OS means "Operating System", or the actual computer program that is running on the PCM (versus the data tables on the PCM, which can be read/altered by a tuner). Bingo. 2 or 3 bar MAP requires a custom OS.Well that does sound like the way to go - so assuming one reflashes their PCM to support 2-bar mapping, is there a MAF on the market large enough to support that? Or are we talking SD-only above 1-bar? Mr. P. Link to comment Share on other sites More sharing options...
.justin. Posted August 18, 2006 Report Share Posted August 18, 2006 oh damn...i was following unit that last post so what is the OS? Sorry for the geek-speak; OS means "Operating System", or the actual computer program that is running on the PCM (versus the data tables on the PCM, which can be read/altered by a tuner). Bingo. 2 or 3 bar MAP requires a custom OS.Well that does sound like the way to go - so assuming one reflashes their PCM to support 2-bar mapping, is there a MAF on the market large enough to support that? Or are we talking SD-only above 1-bar? Mr. P. <{POST_SNAPBACK}> Running a 2bar in a 1 bar OS may net you slightly lower resolution, but the PCM interpolates the values and you're still able to have fairly accurate fueling. I'm still running a 1 bar OS, and have been doing this for almost a year because I don't think I could upgrade to a 2bar. My data bus is screwed up somehow and my re-flashes crash every couple of times and will only work on the low speed setting... If you fail a full OS reflash early on, the PCM is toast. Link to comment Share on other sites More sharing options...
misterp Posted August 18, 2006 Report Share Posted August 18, 2006 Running a 2bar in a 1 bar OS may net you slightly lower resolution, but the PCM interpolates the values and you're still able to have fairly accurate fueling. I'm still running a 1 bar OS, and have been doing this for almost a year because I don't think I could upgrade to a 2bar. My data bus is screwed up somehow and my re-flashes crash every couple of times and will only work on the low speed setting... If you fail a full OS reflash early on, the PCM is toast. Damn man - that's a pisser. GM should've put a UNDO button on the dash... Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted August 18, 2006 Report Share Posted August 18, 2006 oh damn...i was following unit that last post so what is the OS? Sorry for the geek-speak; OS means "Operating System", or the actual computer program that is running on the PCM (versus the data tables on the PCM, which can be read/altered by a tuner). Bingo. 2 or 3 bar MAP requires a custom OS.Well that does sound like the way to go - so assuming one reflashes their PCM to support 2-bar mapping, is there a MAF on the market large enough to support that? Or are we talking SD-only above 1-bar? Mr. P. <{POST_SNAPBACK}> SD only -- but to be honest if you need a 2 bar MAP you are maxing the MAF most likely. Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted August 18, 2006 Report Share Posted August 18, 2006 oh damn...i was following unit that last post so what is the OS? Sorry for the geek-speak; OS means "Operating System", or the actual computer program that is running on the PCM (versus the data tables on the PCM, which can be read/altered by a tuner). Bingo. 2 or 3 bar MAP requires a custom OS.Well that does sound like the way to go - so assuming one reflashes their PCM to support 2-bar mapping, is there a MAF on the market large enough to support that? Or are we talking SD-only above 1-bar? Mr. P. <{POST_SNAPBACK}> Running a 2bar in a 1 bar OS may net you slightly lower resolution, but the PCM interpolates the values and you're still able to have fairly accurate fueling. I'm still running a 1 bar OS, and have been doing this for almost a year because I don't think I could upgrade to a 2bar. My data bus is screwed up somehow and my re-flashes crash every couple of times and will only work on the low speed setting... If you fail a full OS reflash early on, the PCM is toast. <{POST_SNAPBACK}> Hmmm. I don't think that's true with EFI Justin -- it recovers IIR. You can do the 2 bar map in a 1 bar os if you can tweak the MAP scaler, but the difference between doing so and a 2 bar OS is night and day. My experience only applies to EFI Live Custom OS -- I left HPT back when they couldn't support 2 bar tuning for our trucks and didn't know when they would. Link to comment Share on other sites More sharing options...
.justin. Posted August 18, 2006 Report Share Posted August 18, 2006 oh damn...i was following unit that last post so what is the OS? Sorry for the geek-speak; OS means "Operating System", or the actual computer program that is running on the PCM (versus the data tables on the PCM, which can be read/altered by a tuner). Bingo. 2 or 3 bar MAP requires a custom OS.Well that does sound like the way to go - so assuming one reflashes their PCM to support 2-bar mapping, is there a MAF on the market large enough to support that? Or are we talking SD-only above 1-bar? Mr. P. <{POST_SNAPBACK}> Running a 2bar in a 1 bar OS may net you slightly lower resolution, but the PCM interpolates the values and you're still able to have fairly accurate fueling. I'm still running a 1 bar OS, and have been doing this for almost a year because I don't think I could upgrade to a 2bar. My data bus is screwed up somehow and my re-flashes crash every couple of times and will only work on the low speed setting... If you fail a full OS reflash early on, the PCM is toast. <{POST_SNAPBACK}> Hmmm. I don't think that's true with EFI Justin -- it recovers IIR. You can do the 2 bar map in a 1 bar os if you can tweak the MAP scaler, but the difference between doing so and a 2 bar OS is night and day. My experience only applies to EFI Live Custom OS -- I left HPT back when they couldn't support 2 bar tuning for our trucks and didn't know when they would. <{POST_SNAPBACK}> If it bombs in the first 15k of a full reflash, the PCM is toast... It's a small window, but when I do a PCM read on it, it will hang no less than two times. I'm afraid that I'd erase the flash mem, then never be able to fully re-flash the custom OS. I'll bet I could get it working if I electrically isolate the PCM, just haven't gotten around to it yet. Link to comment Share on other sites More sharing options...
popeye55 Posted August 19, 2006 Author Report Share Posted August 19, 2006 wow i though i was lost before.....now I"M LOST guess thats how you learn though. glad i posted my question. I am sure if i had efi live i'd understand more. thanks for all input Link to comment Share on other sites More sharing options...
BenKey Posted August 22, 2006 Report Share Posted August 22, 2006 oh damn...i was following unit that last post so what is the OS? Sorry for the geek-speak; OS means "Operating System", or the actual computer program that is running on the PCM (versus the data tables on the PCM, which can be read/altered by a tuner). Bingo. 2 or 3 bar MAP requires a custom OS.Well that does sound like the way to go - so assuming one reflashes their PCM to support 2-bar mapping, is there a MAF on the market large enough to support that? Or are we talking SD-only above 1-bar? Mr. P. <{POST_SNAPBACK}> Running a 2bar in a 1 bar OS may net you slightly lower resolution, but the PCM interpolates the values and you're still able to have fairly accurate fueling. I'm still running a 1 bar OS, and have been doing this for almost a year because I don't think I could upgrade to a 2bar. My data bus is screwed up somehow and my re-flashes crash every couple of times and will only work on the low speed setting... If you fail a full OS reflash early on, the PCM is toast. <{POST_SNAPBACK}> Hmmm. I don't think that's true with EFI Justin -- it recovers IIR. You can do the 2 bar map in a 1 bar os if you can tweak the MAP scaler, but the difference between doing so and a 2 bar OS is night and day. My experience only applies to EFI Live Custom OS -- I left HPT back when they couldn't support 2 bar tuning for our trucks and didn't know when they would. <{POST_SNAPBACK}> If it bombs in the first 15k of a full reflash, the PCM is toast... It's a small window, but when I do a PCM read on it, it will hang no less than two times. I'm afraid that I'd erase the flash mem, then never be able to fully re-flash the custom OS. I'll bet I could get it working if I electrically isolate the PCM, just haven't gotten around to it yet. <{POST_SNAPBACK}> I have an old LS1 edit cable that may allow you to do just that - should work. LS1 edit never used the ALDL connector. You hooked straight to the PCM. I just moved my household, so it would take a little while to find it, but I should be able to if you're interested. Link to comment Share on other sites More sharing options...
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