GI.SS Posted January 20, 2014 Report Share Posted January 20, 2014 I'm trying to wrap my head around the differences between the different bars? Also the difference with a speed density tune? Is there a good write up on this! Quote Link to comment Share on other sites More sharing options...
2003_SuperSport Posted January 20, 2014 Report Share Posted January 20, 2014 (edited) I by no means covered it all but just to get an idea and if I am off on the numbers a little bit its just examples LOL---- To be kinda brief, which I don't think there is a way to be LOL... 2bar and 3bar are measurements of atmospheric pressure but the definition of mapping gets less detailed as you go up in bars... Just as an example, lets say Atmospheric pressure is 100KPA,(105KPA I beleive stock sensors go up to) thus a standard NA vechicle will be equiped with a 1bar MAP sensor... Now if you are supercharged, or turboed and forcing more air/oxygen than what the engine naturally can suck, then you will be reading above 100KPA and a 2bar (200KPA) MAP sensor is needed to accuratley read boost pressures... For instance at 10PSI boost you may read 175-185KPA while at 20PSI you will read maybe 250 or little more KPA... Thus a 2.5BAR MAP would be required for more accurate tuning since it will read up around 250KPA... A 3BAR most likely will never be needed for most people except in very high boost applications... As far as Speed density goes, for a short answer , SD takes readings from the IAT sensor, MAP sensor, and RPM TPS... Thus not needing the MAF Sensor if your IAT is relocated... In general a SD is used on more aggressive FI motors that go above the boundries of what a MAF can read... Generally anything above 10-12PSI of boost is maxing out a stock MAF sensor and a SD tune or larger aftermarket MAF is required, but the only way to know if it is, is to do a data log and measuring MAF in HZ to see if it is going above the maximum HZ allowed by the stock MAF... SD is also said to be more affected by drastic weather changes and elevation changes because of the set programming in the PCM required to run SD since a SD tune has know way of reading actual air intake... Thus used only for Higher horsepower and higher Boosted motors which are NOT normally driven as DD's or cross country... Some will say its fine and others say absolutley no, also you can justify it if you live in a climate that has a fairly steady climate year round unlike me where it goes from 100's in the summer to -50 below in the winter, Fortunatley I have another DD and only drive my SSS in the summer and I also run SD Tune due to pushing the limits of my stock MAF and wanting to eliminate it all together LOL... Here are a couple of reference pages I quickly found.... http://www.pcmforless.com/index.php?option=com_content&view=article&id=126:speed-density-sd-vs-mass-air-flow-maf-&catid=34:tuning&Itemid=56 http://ls1tech.com/forums/pcm-diagnostics-tuning/1195505-maf-vs-speed-density.html Edited January 20, 2014 by 2003_SuperSport (see edit history) Quote Link to comment Share on other sites More sharing options...
GI.SS Posted January 20, 2014 Author Report Share Posted January 20, 2014 That's exactly what I was looking for! Also isn't there a psi limit for 1 bar, 2 bar, etc? Quote Link to comment Share on other sites More sharing options...
AKSSS Posted January 20, 2014 Report Share Posted January 20, 2014 Referencing 1 bar, is more of a measurement. Super_sport hit it head on, but you have to add the map after the 1bar. 1bar map. I can't remember the exact number for 1 bar, but I think it is almost the same as stoch afr. When referencing the map sensor 1 bar 14psi (atmospheric like ^ said)(zero boost) 2 bar 28psi (but now to get what psi of boost the sensor will read you have to take away atmospheric) So this sensor will read up to 14psi of boost. 3 bar 42psi (once again, you have to take away the first 14psi of the atmosphere) This sensor will read 28psi of boost. When you are talking about fuel, our trucks run at 4 bar(58psi) for fuel pressure. The cars run their fuel systems at 3 bar(43.5psi) . As for the speed density tuning, I have been running speed density for over 5 years in North Pole, Alaska. If it is tuned properly you will not have ANY problems. The only time I have had a problem was when I drove on a long trip and got over 10k ft elevation, I had a slight stumble in the truck. So when I got to the first pull off I turned the truck off and restarted it. I'm not sure if the barometer sensor was not keeping up or what. But when I started it right back up, it ran just fine. That has only happened one time. Quote Link to comment Share on other sites More sharing options...
jovanny Posted January 20, 2014 Report Share Posted January 20, 2014 I by no means covered it all but just to get an idea and if I am off on the numbers a little bit its just examples LOL---- To be kinda brief, which I don't think there is a way to be LOL... 2bar and 3bar are measurements of atmospheric pressure but the definition of mapping gets less detailed as you go up in bars... Just as an example, lets say Atmospheric pressure is 100KPA,(105KPA I beleive stock sensors go up to) thus a standard NA vechicle will be equiped with a 1bar MAP sensor... Now if you are supercharged, or turboed and forcing more air/oxygen than what the engine naturally can suck, then you will be reading above 100KPA and a 2bar (200KPA) MAP sensor is needed to accuratley read boost pressures... For instance at 10PSI boost you may read 175-185KPA while at 20PSI you will read maybe 250 or little more KPA... Thus a 2.5BAR MAP would be required for more accurate tuning since it will read up around 250KPA... A 3BAR most likely will never be needed for most people except in very high boost applications... As far as Speed density goes, for a short answer , SD takes readings from the IAT sensor, MAP sensor, and RPM TPS... Thus not needing the MAF Sensor if your IAT is relocated... In general a SD is used on more aggressive FI motors that go above the boundries of what a MAF can read... Generally anything above 10-12PSI of boost is maxing out a stock MAF sensor and a SD tune or larger aftermarket MAF is required, but the only way to know if it is, is to do a data log and measuring MAF in HZ to see if it is going above the maximum HZ allowed by the stock MAF... SD is also said to be more affected by drastic weather changes and elevation changes because of the set programming in the PCM required to run SD since a SD tune has know way of reading actual air intake... Thus used only for Higher horsepower and higher Boosted motors which are NOT normally driven as DD's or cross country... Some will say its fine and others say absolutley no, also you can justify it if you live in a climate that has a fairly steady climate year round unlike me where it goes from 100's in the summer to -50 below in the winter, Fortunatley I have another DD and only drive my SSS in the summer and I also run SD Tune due to pushing the limits of my stock MAF and wanting to eliminate it all together LOL... Here are a couple of reference pages I quickly found.... http://www.pcmforless.com/index.php?option=com_content&view=article&id=126:speed-density-sd-vs-mass-air-flow-maf-&catid=34:tuning&Itemid=56 http://ls1tech.com/forums/pcm-diagnostics-tuning/1195505-maf-vs-speed-density.html It would be cool to know what all that means ! Quote Link to comment Share on other sites More sharing options...
GI.SS Posted January 20, 2014 Author Report Share Posted January 20, 2014 It has to Do with how your engines sensors fiction causing it to react certain ways. But on another note, if you switch to a 2 bar map then you have to use 2 bar map in your tune which you have to buy separately ? Same as 3 bar with hpt? I'm trying to wrap my head around all this in case I get tired of filling bottles and upgrade to a billet s480 Quote Link to comment Share on other sites More sharing options...
AKSSS Posted January 20, 2014 Report Share Posted January 20, 2014 If you upgrade to a 2bar sd tune using hptuners, yes you have to pay for the upgrade and in turn you end up running a custom os(operating system). Everyone just calls it a 2bar sd tune, but it is a custom tune strictly to hptuners. I use to think that efi live could read my 2bar sd tune, but only hptuners can. Quote Link to comment Share on other sites More sharing options...
Bigtoyz97 Posted January 21, 2014 Report Share Posted January 21, 2014 What SuperSport is saying is the SD mode gets fueling from calculating the MAP, IAT, TPS, sensors and RPM's and the use of the VE table. Closed loop uses the MAF and the O2's....with the O2's varying back and forth to try and keep it at 14.7:1 and there are more tables that come into play.....STFT's and LTFT's and Cell block's and other maps and charts. Closed loop with PE enrichment uses tables for WOT once you hit a predetermined KPA that you are able to set with most programs now Open loop uses MAF and CLT's till the O2's come up to temp 1 bar is 14.7 vac to atmospheric pressure 2 bar is 14.7 vac to 14.7 psi 3 bar is 14.7 vac to 29.4 psi and so on just add 14.7 to each bar going up hope it clears a few things up.....These guys on here know more than I do I'm sure. Just trying to help clarify. Quote Link to comment Share on other sites More sharing options...
2003_SuperSport Posted January 21, 2014 Report Share Posted January 21, 2014 What Bigtoyz97 aka Patrick is trying to say about open and closed loop is: A vehicle will always start out in a open loop operation with rpms above 400.. which is a predetermined air fuel mixture set in the programming until engine temp coolant reaches a certain degree... Once that certain degree is met the ECM/PCM goes into a closed loop thus reading actually AFR from the O2 sensors and adjusting many times a second to give you optimal fuel economy at partial throttle and cruising operations... Once your throttle is above roughly 75% or WOT it then goes into Open loop again to a predetermined AFR from your PE table.. FYI, Whats up Patrick? Quote Link to comment Share on other sites More sharing options...
Bigtoyz97 Posted January 22, 2014 Report Share Posted January 22, 2014 TROLLER....hey Sup James......ha ha Man my bad I forgot that was your user id....or I really would had fun with yeah! Quote Link to comment Share on other sites More sharing options...
chpspecial Posted January 24, 2014 Report Share Posted January 24, 2014 The cliff notes to MAF vs SD tune is that a MAF tune tunes in real time based on actual air coming into the motor. The O2 sensors simply verify that the maf is operating properly and make needed adjustments if necessary. An SD tune goes off of predicted values using multiple different sensors and tables. Sent from my HTC6500LVW using Tapatalk Quote Link to comment Share on other sites More sharing options...
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