Tightmopedman9

Tuners Rejoice! Free Tuning For M4.4!

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Some time ago I made this device for real time data display. It just uses the logging mode of the bin. The first few seconds with the contact on II, you have the opportunity to switch between OBD or Mercuric logging. Both persistent.

Works fine.

2014030204.jpg

Displays AFR, coolant temp, boost pressure, knocks, LTFT-PL and STFT and in the future maybe more nice real time data.

But now I want to start writing log files with this unit in TunerPro XDL format to an SD card. Far more handy than connecting a laptop each time you do a logging trip.

Just put a SD card in the unit, make drive and put the SD card in your laptop or PC for further analysis. When I get this working. ;)

I Already did a post on the TunerPro forum regarding this subject.

Maybe someone over here has some information regarding the XDL internal file layout.

Regards,

Yits.

  • Upvote 2

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Link doesn't work for me - but why would you buy a gauge type sensor for our purposes? You need a absolute pressure/voltage scaled unit for logging & boost control, no?

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I was able to finally capture an example of stall during warmup, if anyone has time to look it over - 20sec clip, stall begins around 19.839 - timing begins to climb (over usual 12-12.75 during this temp range) as revs drop & load increases. At least I can see the Maf volt/flow range where it occurs - I can try lowering the flow value in that range a touch. I don't understand why the volt/flow remains so high even when the revs have dropped off below sustainable running level.

OK - after trying a couple of MAF table tweaks, and minor idle range timing tweaks with no result (as far as the stall during warmup is concerned), I decided to revisit the rpm scaling/axes, since there has to be a reason M4.4 has such close columns in low rpm range. I dropped the 90 rpm column & added the 1050 column, and shifted the fuel & timing values accordingly. AFR sweep on decel/stop is also better than previous revisions.

Screenshot2014-03-23214114_zps1381f0d6.p

It was 18 degrees F (where is the degree symbol on a PC keyboard???? Option-0 on a Mac...) this morning, and whilst there was a drop where the AFR's still stayed in the low 10's briefly, there was no sign of it stalling out. Also with the current settings my PL trim is now +/-.78

Screenshot2014-03-24151926_zps283a2dc7.p

Now I need to revisit some of my earlier revisions, using the current rpm axes

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Link doesn't work for me - but why would you buy a gauge type sensor for our purposes? You need a absolute pressure/voltage scaled unit for logging & boost control, no?

Weird. The link is working ok here.

Why wouldn't I buy it? The only difference should be the atmospheric pressure and I bought the gauge type because I think it may be a little bit more accurate because in tunerpro you would have always to subtract a static value for amospheric pressure (and not a dynamic one), 14.7psi or something, which may be ok in some days/places but wouldn't work so great in places with different altitudes etc. I know the difference is that much but this gauge should work ok anyway. So why not?

I'm just confused about the pressure range etc...

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The data sheet I looked at only said 0-250kPa, I don't recall it saying anything about being a gauge sensor. If it were a gauge sensor, it's values would not be indicated in kP(absolute), correct?...

the a in kPa is simply part of the abbreviation for "Pascal", Pa. It does not indicate absolute or gauge like psia/psig does.

For the degree symbol, hold down alt and on the numpad enter in 167: º

Weird. The link is working ok here.

Why wouldn't I buy it? The only difference should be the atmospheric pressure and I bought the gauge type because I think it may be a little bit more accurate because in tunerpro you would have always to subtract a static value for amospheric pressure (and not a dynamic one), 14.7psi or something, which may be ok in some days/places but wouldn't work so great in places with different altitudes etc. I know the difference is that much but this gauge should work ok anyway. So why not?

I'm just confused about the pressure range etc...

You would want absolute, because as you say, the gauge pressure isn't always exactly same, due to environmental differences. Ultimately, the point of using said sensor is to determine the density, thus the mass of oxygen in each combustion chamber, so an appropriate amount of fuel can be injected. If the sensor is giving a gauge reading, 10psi at sea level will be a lot different than 10psi when driving over Independence pass! I don't get why tunerpro would subtract a static value; from an engineering perspective, it makes zero sense.

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the a in kPa is simply part of the abbreviation for "Pascal", Pa. It does not indicate absolute or gauge like psia/psig does.

For the degree symbol, hold down alt and on the numpad enter in 167: º

You would want absolute, because as you say, the gauge pressure isn't always exactly same, due to environmental differences. Ultimately, the point of using said sensor is to determine the density, thus the mass of oxygen in each combustion chamber, so an appropriate amount of fuel can be injected. If the sensor is giving a gauge reading, 10psi at sea level will be a lot different than 10psi when driving over Independence pass! I don't get why tunerpro would subtract a static value; from an engineering perspective, it makes zero sense.

kPa does not mean absolute but somewhere in the data sheet it says it is absolute so I assume it is 0-250kPa absolute.

Why the gauge type is useless? Our boost gauges above 0 reads PSIG and who cares?

If I really want to know all the air is going into the engine I can read the maf output or the map output for absolute pressure.

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"

the a in kPa is simply part of the abbreviation for "Pascal", Pa. It does not indicate absolute or gauge like psia/psig does."

Thanks for the correction, Mark

"For the degree symbol, hold down alt and on the numpad enter in 167: º"

You mean alt key and 9? What's the colon for?

If you are using the pressure to inform the EMS or for precise boost control, you want absolute. Guage pressure is not accurate enough for that. Maybe the margin of error is ok for you. I would have problems with it since at my level every 1psi increase is = 15+AWHP, critical difference when tuning

I don't believe TunerPro makes any correction for kPa absolute / gauge- I do believe you would have to add that to the Guage formula if you do t want it do display absolute value (and subtract atmospheric in your head)

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Since the absolute pressure sensor is referenced against a vacuum the maximum boost pressure it can read is decreased by the current barometric pressure. If you're at sea level this is 14.7psi, which means that the maximum recordable boost pressure is 21.6psi, not high enough for my needs. Not to mention, with an absolute pressure gauge variations in barometric pressure will shift the reading unless corrected for. Why does reading vacuum even matter?

If you are using the pressure to inform the EMS or for precise boost control, you want absolute. Guage pressure is not accurate enough for that. Maybe the margin of error is ok for you. I would have problems with it since at my level every 1psi increase is = 15+AWHP, critical difference when tuning

I don't believe TunerPro makes any correction for kPa absolute - you would have to add that to the Guage formula if you do t want it do display absolute value (and subtract atmospheric in your head)

The ECU isn't doing anything with the data, so it doesn't matter. Optimally you want 2 absolute pressure sensors, one for determining pressure and the other for barometric corrections.

Edited by Tightmopedman9

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"

the a in kPa is simply part of the abbreviation for "Pascal", Pa. It does not indicate absolute or gauge like psia/psig does."

Thanks for the correction, Mark

If you are using the pressure to inform the EMS or for precise boost control, you want absolute. Guage pressure is not accurate enough for that. Maybe the margin of error is ok for you. I would have problems with it since at my level every 1psi increase is = 15+AWHP, critical difference when tuning

I don't believe TunerPro makes any correction for kPa absolute / gauge- I do believe you would have to add that to the Guage formula if you do t want it do display absolute value (and subtract atmospheric in your head)

No, I will use the sensor only to log boost along with the other parameters.

When I talk about tunerpro correction is only because I want to read pressure above atmospheric, like my boost gauge. And then, when using an absolute sensor if I want to get only psig I need to subtract atmospheric pressure which is not static, it is dynamic. So I prefer to use a gauge sensor so I don't have to worry about the atmospheric pressure (I understand it is usefull but not for me at this moment - probably if I see it makes more sense i will change for a absolute one).

What is confusing me is that data sheet once it talkes about absolute pressure...

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?

The ECU isn't doing anything with the data, so it doesn't matter. Optimally you want 2 absolute pressure sensors, one for determining pressure and the other for barometric corrections.

If the potential for MAP conversion exists, it may matter :-)

M4.4 cars already have this barometric pressure sensor...for precisely that reason (compensation)

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sig I need to subtract atmospheric pressure which is not static, it is dynamic. he...

Unless you live in an area with extremes of topography I can't see how it makes a difference. You find out what the value is for your region, end of problem.

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Unless you live in an area with extremes of topography I can't see how it makes a difference. You find out what the value is for your region, end of problem.

Today I drove through 7,000ft of elevation change. The barometric pressure difference was ~2psi between the lowest and highest point. I do this at least twice a week. Not to mention, due to local weather the pressure will vary up to .8psi a day on average.

Edited by Tightmopedman9

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Unless you live in an area with extremes of topography I can't see how it makes a difference. You find out what the value is for your region, end of problem.

I know that but if I can solve the barometric pressure "problem" with a gauge sensor why not?

Once I already have the GP sensor the most important here is not to discusse why to use the absolute or gauge sensor but to clarify the meaning of that data sheet... :)

Edited by S70-R

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Not to be rude, but I'm not sure how there is any confusion here. The "GP" variant is clearly indicated within the data sheet to be a gauge version. The "D" and "DP" variants are differential pressure. None of them are absolute.

I still hold the opinion that gauge pressure isn't the most meaningful for the application, but if it's what you want for your logging, I'm sure not gonna stop you! :lol:

Hussein, sorry for the unclear instructions on the degree symbol :lol: Hold the alt key while typing 1 6 7 on the numpad, then release the alt key. 0178 is ², 0179 is ³, 0177 is ±, and so forth; they're called "alt codes".

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Not to be rude, but I'm not sure how there is any confusion here. The "GP" variant is clearly indicated within the data sheet to be a gauge version. The "D" and "DP" variants are differential pressure. None of them are absolute.

I still hold the opinion that gauge pressure isn't the most meaningful for the application, but if it's what you want for your logging, I'm sure not gonna stop you! :lol:

Hussein, sorry for the unclear instructions on the degree symbol :lol: Hold the alt key while typing 1 6 7 on the numpad, then release the alt key. 0178 is ², 0179 is ³, 0177 is ±, and so forth; they're called "alt codes".

Please check page 4 of the data sheet http://cache.freescale.com/files/sensors/doc/data_sheet/MPX4250.pdf?fasp=1&WT_TYPE=Data%20Sheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation&Parent_nodeId=C966661558306&Parent_pageType=product

It says "Figure 4. Output versus Absolute Pressure"

If this sensor reads 0-250kPa above atmospheric, so it reads 36,3psig? I don't think so, it seems it would be too good to be true.

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