Hondata and GM 3Bar

[Dariusz]

I make a very interesant discovery... the GM 3Bar have a error in reading the positive pressure (boost).

Yesterday I make a run in the Dyno with the logger and I'm very concern as my boost gauge read 10 psi and the logger read only 6.5 psi. I think that my gauge (Greddy) is damage and I connect a calibrated profesional instrument gauge that we use in the lab... and surprise the reading of the Greddy is fine (minimal difference). I check the voltage that come from the GM 3Bar and the Hondata convert it to psi good, but the reading od the GM 3Bar have diffrences from 3 to 4.5 psi less that the actual value.

I make other test, I connect a calibrated possitive pressure pump to the GM 3Bar and it read 3 to 4.5 psi less that the real value.

I try 6 different GM 3Bar units (2 from MSD, 3 from Hondata and 1 direct from GM) and the results are the same.

I write this that all take in consideration this problem in tunning.

I think that Hondata knowing this issue can make a little convertion in the software...

[Hondata]

Can you post your results? When I added the 3 bar capabilities to Hondata I calibrated about 4-5 3 bar MAP sensors, and they all agreed to within 0.01 volts of each other. Are you performing the tests using the vehicle wiring loom or out of the car? A good quick test that the voltage at atmospheric pressure (key on, engine off) should be 1.61V (at sea level with normal weather conditions).

[Dariusz]

The problem is not the calibration, I have a pressure / voltage table from 0.00 bar to 3.00 bar (0 to 5 volts) and the reading are OK (Rom editor voltage to psi conversion is OK using the voltage he receive from the 3bar as reference). The problem is that the voltage the 3Bar send (the read he make) is not accurate to the one you obtain with other instruments...
In example, I generate 10.5 psi of possitive presure using a calibrated pump , connect the vacoom line in a Y and put a calibrated gauge in one side and the 3bar in the other side. The calibrated gauge reads 10.41 psi (0.73 Kgf/cm2) and the 3bar send 2.44 volts (aprox. 1.47 bar = 6.8 psi).
As I can see in my tests, the difference move from aprox 2.7 to 4 psi (in different pressure readings).
The detail in all this tests is that the readings the people view in the logger or the Rom editor are less that the real one he have, and the tunning is less accurated that can be.

Other comment, I make the tests in the vacoom side of the readings and the 3bar work good and accurated.

In ansver for your question in my city I have a air pressure of 950 and I compensate the logger, and in accordance to this my reading from the 3bar is 1.59 volts (at sea level the normal is 1.67). I think that this difference is good.

[Hondata]

How are you powering the 3 bar MAP sensor? How close to 5V is your power supply?

[Dariusz]

With the key On and the Engine Off= 4.7 v
With the key On and the Engine On= 4.96 to 5.02 v

Is important to say, that is possible to obtain different readings if you use the ground in the 3 bar connector or you use the ground in example in the engine (2 different points to connect the cable from the voltmeter). I make the tests using the ground in the chassis of the car, becouse I think that this is the exact ground that the Ecu use.

[Hondata]

You need to test the MAP sensor outside the vehicle in a test harness, otherwise it is not a test of the MAP sensor, it is a test of the MAP sensor, ECU and vehicle wiring.

[Dariusz]

I make this too and the result is the same (as I say you before I test 6 different sensors, all gm 3bar but sell by different vendors...). Part of the test is make a connection direct to the sensor and review the voltage that the sensor send.

[QUICKSILVER RACING]

Something similar to this happened to me. But I was using the stock MAP sensor. The boost gauge reads 14psi while the logger reads 11psi.

I ignored it thinking that the boost gauge was in question.

[Hondata]

Send me the results from the testing you have done and I'll look into it.

[Dariusz]

Derek, I need to search for my papers (lots of mini sheets of paper I use to make the anotations) and make a clean of the numbers.

I trie to have it this week and I send you it.

[TorinF]

Something similar to this happened to me. But I was using the stock MAP sensor. The boost gauge reads 14psi while the logger reads 11psi.

I ignored it thinking that the boost gauge was in question.

i've reported the same errors, about 3-4psi higher readings with other pressure sensors hooked to the manifold. Its a bug for sure.

[ton]

Is this boost problem only a concern on s200 or is it also a problem for stage4? The reason I ask is that I am at 26psi boost and a -+ 3 psi is really scary thought.

thanks
ton

[Dariusz]

I like to aclarate some details, reading the posts of other people:

1) This in not a bug of the S-200 (or other Hondata software), as I write in one of my posts (in this thread) this is a problem in the GM 3bar reading.

2) The difference in reading can be a gauge problem in some cases (a lot of cases), in my tests, I test 3 different gauges (1 mechanic autometer, 1 greddy and 1 apexi) and in all (yes in all) are different readings at the same level of possitive pressure (the greddy is the most accurated in my case). I use a calibrated gauge (special to lab work) to have a TRUE base reading.

3) I only make the tests to 13 psi I can't say what are the readings in higher levels of boost.

4) My inicial comment is to save other people all the work I need to make to know about this detail, and use this information in tunning to have a better work.

Please all, excuse my bad english.

[TorinF]

[quote="Dariusz"]I like to aclarate some details, reading the posts of other people:

"1) This in not a bug of the S-200 (or other Hondata software), as I write in one of my posts (in this thread) this is a problem in the GM 3bar reading.
"

I disagree with you. I have verified this on 4 cars now and this is a calibration error within the Hondata software for the voltage output from the 3bar MAP sensor to pressure. I would trust a mechanical gauge and a well calibrated electronic sensor over the Hondata datalogging at this point. I hope that Hondata will correct this as well as several other small annoyances withing their software since it can be a detriment for anyone trusting the boost pressure readings off this software.

[Dariusz]

I disagree with you. I have verified this on 4 cars now and this is a calibration error within the Hondata software for the voltage output from the 3bar MAP sensor to pressure. I would trust a mechanical gauge and a well calibrated electronic sensor over the Hondata datalogging at this point. I hope that Hondata will correct this as well as several other small annoyances withing their software since it can be a detriment for anyone trusting the boost pressure readings off this software.

I make the test using a positive pressure generator and as you can see in my second mensage the voltage reading for the real pressure that come from the GM 3bar is not correct.

In example, I generate 10.5 psi of possitive presure using a calibrated pump , connect the vacoom line in a Y and put a calibrated gauge in one side and the 3bar in the other side. The calibrated gauge reads 10.41 psi (0.73 Kgf/cm2) and the 3bar send 2.44 volts (aprox. 1.47 bar = 6.8 psi).

As you cans see exist a error and is consistent with the other GM 3bar I test.

I'm a simple user of the s-200 in my car, but I think that this type of information is important to share with others users.