bryan01 Posted May 28, 2007 Share Posted May 28, 2007 ms1 v2.2 v26 msextra at idle my car is reading 38 kpa. barometric reading is 94. thats a HUGE vacuum (double) over what it should be at idle. i found this in the megasquirt info files If the MAP sensor reads too low or too high by a factor of 2, you can check that your MegaSquirt MAP sensor is reading too low, but responds to vacuum and pressure, then you have the wrong ".inc" files in your MegaTune folder. Copy the files (you need are "kpafactor.inc" and "barofactor.inc") from the "Turbo" sub-folder into your MegaTune folder, and everything should work. Place the correct files in your MegaTune directory (for older versions), or in the mtCfg folder (if it exists). (The "turbo" files refer to the ability of the MPX4250 MAP sensor to sense boost, not to the actual configuration of the engine.) i bought my squirt used, so i thought i may have a different map sensor, i took it apart and it's the standard mpx4250ap. since the scenario above matched my problem almost exactly i looked for the "turbo" sub-folder in the megatune install files, and the megatune installed directory and couldn't find it. there were a few different files in the main directories thou, like kpafactor4250 or just kpafactor. my megatune (latest version) is pulling from a file called kpafactor4250. i copied the kpafactor file i found in my megatune install files (not from the "turbo" folder, b/c that doesn't exist) into the installed folder and had to change the name to kpafactor4250 so it would read correctly, but got the same result. any ideas? Quote Link to comment Share on other sites More sharing options...
zbigtim Posted May 28, 2007 Share Posted May 28, 2007 Bryan, I never paid attention to this until your post. I just installed my MSII v30. and it appears I have the same symptoms you do. I just checked my vacuum with a gauge at idle. It read 18.5 inHg. If I convert that to kpa it equals 62.5. The Megatune 2.2 shows 35kpa. I have not looked into the .inc files yet. Maybe someone can shed some light on this "problem". Tim Quote Link to comment Share on other sites More sharing options...
bryan01 Posted May 29, 2007 Author Share Posted May 29, 2007 it idles fine, but i'm afraid i'll have an incorrect map reading when i start driving around and tuning. i think we just need a certain file that's supposed to come w/ the megatune software, but i can't find it. i tried posting on the ms forums but my account was inactive ... so i'll try that again later Quote Link to comment Share on other sites More sharing options...
bryan01 Posted May 29, 2007 Author Share Posted May 29, 2007 http://www.msefi.com/viewtopic.php?p=170248#170248 i posted on the megasquirt forum and someone said it was fine. i still dont get it thou, what do you think (anybody)? does this make sense? Quote Link to comment Share on other sites More sharing options...
bryan01 Posted May 29, 2007 Author Share Posted May 29, 2007 haha, i'm kicking myself in the foot. in your case 18.5 INCHES OF MERCury is what a gauge reads .... not KPA .... 18.5" = 62.6kpa .... then take that minus atmospheric, and you get what your megasquirt is spitting out so in my case, barometric reading of 94kpa=atmospheric minus 38 kpa (what my squirt is reading) = 56kpa= 16.5inHG. yeah ... it's reading correctly ... Quote Link to comment Share on other sites More sharing options...
zbigtim Posted May 30, 2007 Share Posted May 30, 2007 Ah yes, The difference between absolute pressure and guage pressure! Very much the same as the difference between PSIA and PSIG. 0 psig (guage pressure) = 14.7 psia (absolute) Quote Link to comment Share on other sites More sharing options...
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