air pressure sensor

[Elmelo]

Good morning and happy new year, excuse me if in my comment rare words appear, I use the google translator since my written English is not very fluent. I have a special california of the year 2000. After solving many problems derived from the excessive oxidation in the tank, the bike was working acceptably although I still have problems when I drive at high altitudes (more than 2,000 meters) I live in the Canary Islands on a very high island .
Guzzidiag identifies the ecu model 61600.381.00 and the map GCE3901
Several months ago, several friends of this group kindly sent me several maps,
 among them an original GCE3901 which gave me the opportunity to compare it with mine and thus rule out that my map had not been touched.The map that worked very well is the one that Beetle sent me, identified as 61600.381.00_GCE390 1_California_Specia l, the motorcycle has more power, fuel tables, ignition and trims are identical to the original jackal software that another friend sent me. However, the problem with atmospheric pressure persists. Suspecting to have a problem with the pressure sensor, yesterday I took the ecu, (I already did it on one occasion to review cracked welds on the connector pcb)
As it turns out that the model of the ecu is 61600.428.01 finding out a little on the internet that is the ecu of a quota. And the most surprising thing was that the sensor cannot measure the external pressure if it is completely enclosed, I explain ... there is a hole in the ecu, with a black plastic button inside the button there is another piece of white plastic, I deduce that that white piece should be a flexible membrane that translates the external pressure to the sensor, but no, the white piece is completely rigid and completely plug the hole. I do tests, blow or suck on the black button and nothing, guzzidiag still indicates the same pressure. I remove the plastic, suck and I can see how the pressure drops, I blow and the pressure rises. Ok the sensor works.
It is not good to blow a lot, since saliva is introduced and then when I started it was very bad, I had to open and dry the circuit. Of course I will go out to test the bike without the plastic part, but ... does anyone know anything about this subject? because it is clear that with the plastic piece the sensor is inactive and I have already seen in some forums people commenting that guzzidiag indicates incoherent pressures.

[chuck peterson]

Your English translation came through very well. I understood your question perfectly. So well, in fact, that I know the question you asked of air pressure sensors is way above my head. In fact I've never heard of this discussion before.

The silence you hear would be everyone scratching their heads. Someone's likely to come along that's had some experience with that.

[guzzisteve]

That is interesting, no wonder some 2000 Special Sports w/15M run like crap. I have seen more than a few.

[Elmelo]

I attach some photos:
In the guzzidiag screen you can see how the atmospheric pressure, without the plug, is 1,042 mb, with the plug indicates 1,073, it is true that here we have very good weather, but those values ​​would be the father of all the anticyclones. The usual values ​​at sea level, which is where I am, are around 1,015 ~ 1020 mb.
The rest of the photos are from the ecu, where you can see the sensor, which is partly under the connector, looks like a button cell.
You can also see the black plastic piece, it looks like the outside of a chimney, and you can see the other white plastic piece that is completely rigid and seals any air inlet.

[acguzzi]

could it be a goretex seal gone bad? they are supposed to pass air but keep out water

[Moto]

I did a lot of study of the air pressure sensor used on the Griso and Breva (mounted on the dash's PCB, instead of on the ECU's) so I feel able to make some useful comments.

On the Griso, the dash enclosure is vented with small ports that have baffles to exclude or reduce the inflow of water droplets. Some owners have thought that closing those ports would be a good way to reduce condensation, but this is wrong for the same reason that your ECU needs some connection to the atmosphere.

Contrary to popular beliefs, there are no membranes that can pass air molecules (O2 and N2) while excluding molecules of water (H20) in gaseous form (called water vapor). This is simply because the water molecules turn out to be substantially smaller than the others, due to the way the molecular bonds form. Goretex and other barriers exclude water mist (i.e., droplets) and allow  gaseous water to pass, equilibrating the partial pressure of water vapor with the outside environment.

You need some porting, but maybe not much. It seems possible that your port is designed to have an extremely small flow, enough to equalize air pressure inside and outside the ECU over a period of hours or maybe longer, but quickly enough for most gradual transitions in elevation. It could be that riding on your island the transition is too fast for the equalization to keep up.

Or the factory could just have made a stupid mistake, trying to seal the enclosure against water by replacing an original water droplet barrier with solid plastic, and not realizing the effect this would have on the air pressure sensor.  (Two sets of engineers, perhaps.)

I recommend you run without the plug for a while and see if that helps. If so, drill a tiny hole through the white plastic plug, and cover it with goretex or any other water-droplet resistant barrier, if you like. Is the ECU mounted where water can hit it directly? If so, you should create a guard to keep it off the plug. Alternatively, you could drill a small hole in the other side of the ECU case, out of the water spray.

I think you have found the problem, and just need more porting. Good detective work!

Moto

[beard]

Hi,

a 15M.C1 is the right ECU for the Cali.
And your GCE3901 is the original software.
One year later they used 3D02MM25.

But the main problem is ...
Guzzi did a bad (or no) job to adjust the barometric adjustments for this software.

Meinolf did a lot of tests and measurements about this and he changed the settings for this table by
using the correct barometric formulas. He did this for his V11 also with a 15M ECU.

I'll check his mails about this. Maybe he already posted this here in the forum.

https://wildguzzi.com/forum/index.php?topic=73938.msg1306902#msg1306902

Simply pm him, I'm sure he will send you his version with optimized barometric settings.

[BMCMOTO]

Early Quotas were recalled for funky pressure sensors. The diagnostic procedure was to remove the computer module and give it a shake, if it rattled it got replaced. I don't know if that helps at all.

Brian

[Kiwi_Roy]

The sensor compares atmospheric pressure on one side of a diaphragm to an absolute vacuum on the other so yes the atmosphere side must be able to  breathe so it can compensate for altitude.

[beetle]

What Beard said. The correction tables in the map were next to useless.

[Kent in Upstate NY]

If I recall correctly, you can find lots of Ducati 15M ECUs  that can be over written with Guzzi software. However, I had a similar issue that took 6 months to resolve. I now have an ECU from a V11 Sport with  PC III. Total kludge but it works. I had two well known So Cal Guzzi mechs work on it. Both were kinda flakey.

[beard]

Only informational:

The tables in the GCE3901 (1998) and the 3D02MM25 (2000) are identical.
The software is modified. Other algorithms are implemented.

Then in 2002 there was a 3D02MM26 available.
The software is identical to the MM25, but some tables are changed.

The MM26 looks like more power, since the injection values are increased and the ignition is adjusted in the upper rpms.

Also one value in the barometric table was changed. But only the value for 'normal' pressure.

[Elmelo]

Thank you all for the answers that have clarified some doubts. As Moto says, on my island the pressure changes are abrupt, from 100 meters to 2,500 meters, if we did it in a straight line, there are less than 20 km. Obviously it is not done in a straight line, there is no road and most importantly, it would be very boring. There are roads with many curves but in very good condition that cross the forests that predominate in the medians, and almost without realizing it and when you leave the forest behind you are already entering the roof, volcanic landscape similar to the photos of Mars. 10 km more on a plateau and you're in the 2,800. You can reach up to 3,800 but it is by telespherical and they do not admit motorcycle .
Well, let's go back to where we were ... I never heard the word "goretex" I asked mr google and he showed me results of clothes and shoes, so I deduce that it is a kind of material, like a cloth.
Once again, I check that there is no air, with the button in my hands I adjust it to my lips and blow and blow again harder until I have a toad face, the same test with the ecu connected and looking at the screen with guzzidiag, the Pressure gauge does not move. So I decide to face the button and its partner the white piece, with a fine pointed punch I try to take out the white piece, Ohhh !! It is not a piece of rigid plastic, it is like cloth, it is a filter and like all filters it is not free from clogging. At first I was delicate, but it was so hard that I had to use violence , anyway I have nothing to lose because there has to come air and does not enter. I have not yet gone out to try the bike, I think that if it has improved, even if it is little, it is already something positive despite the impressions on the map that several colleagues have mentioned. If it has improved, I can not leave it with the open hole, the humidity of the air, over time, can wreak havoc on the printed circuit and on the sensor itself. I will have to look for a goretex patch, and now the question arises and it is something that Moto also mentions. And if in the firmware the sensor is calibrated for a certain amount of air flow? Anyway, I think it will be better to go out and try the bike and move on to the next level.
And I make a reflection: If it is a filter and all filters are susceptible to getting dirty and reducing the flow through it or completely blocking it as is my case, shouldn't it be considered as a replacement? same as air filter, gasoline etc ?. I'm talking without knowing maybe I don't know it exists as a spare.

[Kiwi_Roy]

It is very hard to blow a lot of pressure however you can suck quite a significant vacuum.
It does seem that the sensor is plugged, if you are worried about breathing in moisture perhaps run it through some desiccant
or run a hose into a childs ballon that is slack (not inflated), the rubber would take up the changes in volume but exclude any moisture.

[Moto]

There are roads with many curves but in very good condition that cross the forests that predominate in the medians, and almost without realizing it and when you leave the forest behind you are already entering the roof, volcanic landscape similar to the photos of Mars. 10 km more on a plateau and you're in the 2,800. You can reach up to 3,800 but it is by telespherical and they do not admit motorcycle .

Let me know if you'd like to trade houses!

... I decide to face the button and its partner the white piece, with a fine pointed punch I try to take out the white piece, Ohhh !! It is not a piece of rigid plastic, it is like cloth, it is a filter and like all filters it is not free from clogging. At first I was delicate, but it was so hard that I had to use violence , anyway I have nothing to lose because there has to come air and does not enter. I have not yet gone out to try the bike.... If it has improved, I can not leave it with the open hole, the humidity of the air, over time, can wreak havoc on the printed circuit and on the sensor itself.

You need hardly any air flow, just enough to equalize the interior and atmospheric pressures. Your filter (nice job discovering that it is one!) may be just fine, even though you can't seem to blow through it.

Also, your ECU's board may be coated (with a "conformable coating"), so that there is not too much worry of damage from humidity. The Griso's DASH board is not coated, and has this has led to problems. In constrast, the Aprilia RS50 minibike's ECU is coated (according to an expert, Techrat1). I don't know if the Griso's ECU is coated, but I expect it is, since there are no reports of corrosion failure that I remember.

It is possible you could detect the presence of a coating on your ECU's board by using an ultraviolet flashlight. These cost about $10. The aftermarket coatings (like the one I used) are made to fluoresce with a bright blue color in such light (specifically to enable checking for a complete coating). I don't know if this is true for any factory-applied coating, but I think it would be.

I will have to look for a goretex patch, and now the question arises and it is something that Moto also mentions. And if in the firmware the sensor is calibrated for a certain amount of air flow? Anyway, I think it will be better to go out and try the bike and move on to the next level.

The sensor is not calibrated for air flow, but only for pressure. To repeat, even a tiny amount of flow should be enough, provided you don't change altitude too quickly.

Have you thought of putting the white filter back in (with glue around the edges), and then measuring the indicated altitude at your home and also at 2800 meters? If you see the correct amount of change you will be able to conclude that the filter is not the problem. (I would think the amount of change is more important than the absolute readings, but those could also matter.)

Pressure drops about 12 millibars for each 100 meters in elevation above sea level (if you are not too high). So if you did go from sea level to 2800 meters you should see a drop of about 28x12 = 336 millibars (!), to about 680 millibars, I believe. That would tell you your filter is not the problem.

On the other hand, if you find the pressure inside the ECU enclosure is too high, you should check it again after having lunch at a restaurant up there. If you find it has come down substantially your filter may be too restrictive for your mountain playground.

This is an interesting problem you've got. Please let us know what you figure out.

Moto

[Elmelo]

Only informational:

The tables in the GCE3901 (1998) and the 3D02MM25 (2000) are identical.
The software is modified. Other algorithms are implemented.

Then in 2002 there was a 3D02MM26 available.
The software is identical to the MM25, but some tables are changed.

The MM26 looks like more power, since the injection values are increased and the ignition is adjusted in the upper rpms.

Also one value in the barometric table was changed. But only the value for 'normal' pressure.

The software that the ECU had when I bought the motorcycle (second hand) is the GCE3901 The motorcycle never had a decent performance, before I had a Virago 1,100 and I missed my old motorcycle many times.
I began to suspect that the software had been touched by inexperienced hands, it seemed impossible that that was the factory performance (now the more I read in this forum, I see the reality).
Through this forum I received in my mail several softwares that some guys kindly sent me. I received a GCE3901 that compared it with mine and with tunerpro, cleared my doubts because they are exactly the same. I also received a 3D02MM25 that improved the performance somewhat but did not show any atmospheric pressure data 0 on the Diag screen (as I write I am thinking that I may have a karma with the pressure) however and interestingly, in height the bike behaved very well , until it started to go down. They also sent me another GCE3901 and they identified the Diag, however ultimately this, the fuel and spark tables show the same values ​​a 3D02MM25, with the difference that this itself shows the Diag pressure values.

[Elmelo]

Let me know if you'd like to trade houses!You need hardly any air flow, just enough to equalize the interior and atmospheric pressures. Your filter (nice job discovering that it is one!) may be just fine, even though you can't seem to blow through it.

Also, your ECU's board may be coated (with a "conformable coating"), so that there is not too much worry of damage from humidity. The Griso's DASH board is not coated, and has this has led to problems. In constrast, the Aprilia RS50 minibike's ECU is coated (according to an expert, Techrat1). I don't know if the Griso's ECU is coated, but I expect it is, since there are no reports of corrosion failure that I remember.

It is possible you could detect the presence of a coating on your ECU's board by using an ultraviolet flashlight. These cost about $10. The aftermarket coatings (like the one I used) are made to fluoresce with a bright blue color in such light (specifically to enable checking for a complete coating). I don't know if this is true for any factory-applied coating, but I think it would be.
The sensor is not calibrated for air flow, but only for pressure. To repeat, even a tiny amount of flow should be enough, provided you don't change altitude too quickly.

Have you thought of putting the white filter back in (with glue around the edges), and then measuring the indicated altitude at your home and also at 2800 meters? If you see the correct amount of change you will be able to conclude that the filter is not the problem. (I would think the amount of change is more important than the absolute readings, but those could also matter.)

Pressure drops about 12 millibars for each 100 meters in elevation above sea level (if you are not too high). So if you did go from sea level to 2800 meters you should see a drop of about 28x12 = 336 millibars (!), to about 680 millibars, I believe. That would tell you your filter is not the problem.

On the other hand, if you find the pressure inside the ECU enclosure is too high, you should check it again after having lunch at a restaurant up there. If you find it has come down substantially your filter may be too restrictive for your mountain playground.

This is an interesting problem you've got. Please let us know what you figure out.

Moto

I have manufactured printed circuits in a homemade way and normally a spray of lacquer is applied to them that protects from the corrosion, that was the first idea that arose to me, with that I can protect the printed circuit but not the diaphragm of the sensor because obviously if I apply lacquer on I close the sensor and I am in the same situation. I was working with pressure sensors of up to 100kpa to make a digital vacuum gauge and I know that they are piezoelectric and work with pressure and not flow (the google translator is sometimes very funny) these sensors usually have three connection pins, it is very similar to a potentiometer but controlled by the pressure applied to the piezo or diafragam. A fixed reference voltage is applied to one of the pins, in this case it would be 5Volts, a second pin is negative potential and the output pin delivers a certain voltage depending on the pressure. The manufacturer provides the characteristic curve, normally linear, starting from said curve the code is written so that the micro knows that, for example, with a voltage of 3volts, the micro interpreter is 40kpa or 60Kpa and the hardware acts accordingly (I am setting an example on another pressure scale). And that was my doubt, that the filter was somehow so restrictive that when inside the ECU cabin (that the lid is perfectly sealed and therefore is an independent cavity outside) there would be a pressure X the micro would interpret a pressure Y, it means that a certain pressure inside the cavity, would not have to coincide by force with the external pressure or what is the same that the micro does a conversion. Also tell you that when I blow or suck directly into the hole where the button was, the response of the ECU is immediate, in the Diag it is seen how the injection pulse increases or decreases.

[Elmelo]

It is very hard to blow a lot of pressure however you can suck quite a significant vacuum.
It does seem that the sensor is plugged, if you are worried about breathing in moisture perhaps run it through some desiccant
or run a hose into a childs ballon that is slack (not inflated), the rubber would take up the changes in volume but exclude any moisture.

The balloon as a momentary solution while doing tests, is simply great, I thought to put a cigarette filter that fits perfectly in the hole but the balloon is safer. I have seen how several sensors of my digital vacuum gauge died when receiving condensation particles accumulated from the intake connectors and the ECU sensor is difficult to replace, it is under the connector.

[Murray]

Your lungs are more than capable of producing an out of range pressure when compared to barometric pressure. A piezo electric sensor is normally a capsual that wil ossolate at a particular frequency with a voltage applied and have an output relative to that frequency. Most sensors work across a 4-20mA range or 0-5 volts. The relationship of presure to altiude is a non liner relationship so this might be a Bettle question of how the pressure data is applied to the map, is this non liner relationship applied within the sensor or within the map.

If you are handy, can code and have a bit too much time on your hands running a NEMA string through a micoprocessor to simulate the barometric pressure signal might be worth considering. Or finding an external pressure sensor off another injection system its very likely Webber Marelli use that same protocole across all thier ECU's

Dim dark memory with this ECU there was an issue with the cylinder tempreture sensor giving an excessively cool signal and causing a few running issues maybe try V11lemans.com.  I'm just wondering if its a loading issue. When you are climbing the motor is running hot under lead up the mountian. On the way down lots of airflow not a lot of throttle , rather than a failure to read the pressure correctly or maybe even a vacuum leak.

You would think that at Lake Como they have a few mountians this might of been covered off but at the time your bike was manufacturered I don't think they were rolling around in much of a development budget.

[Elmelo]

We start with the filter and we go deeper, regardless of the problem with the filter there are other doubts that assault in relation to the sensor itself, with a software the diagnosis indicates a pressure and with other software and in the same place it indicates another very different .
The sensor nomenclature cannot be read completely because half of the body is under the large connector, you can only read this "S4100A" as the references of these pressure sensors usually start with "MPX" I asked mr google for the "MPXS4100A "And it has brought me the datasheet of what in principle seems to be the sensor at hand. The corrections made by the atmospheric pressure table are considerable and there are some parameters in those tables that I do not understand. The electrical characteristics of the sensor say that the measuring ranges are from 20kpa to 105kpa, using this online converter https://www.convert-me.com/en/convert/pressure/, it remains that it would be from 200mBar to 1,050 mBar. According to the datasheet, the typical (minimum) offset would be that, for an output voltage of 0.306 Volts it would be measuring a minimum of 200mBar that would be the minimum sensitivity and above that the maximum voltage would be over the 4,897 volts that would correspond to 1,050mBar. There is no more, that is the minimum and the maximum and the curve is linear. As you can see in the graph below.







And now I comment on the question I have with the tables. Looking at the tables available in regard to pressure, I see four different windows or parameters: the FUEL TRIM AIR PRESSURE, the AIR PRESSURE LIMP HOME, the AIR PRESSURE MIN and the AIR PRESSURE MAX, the latter two represent voltage values.
And now the million-dollar question ... are these presets related to sensor calibration according to their electrical characteristics mentioned above?

Because if so ... and as you can see in the following photo of a GCE3901 software, the AIR PRESSURE MIN is preset at 0.06 Volts when it should be at 0.306Volts which would be the sensor offset, indicated by the manufacturer (the point starting) if you start reading out of range, it will be out of range throughout the curve. All this is speculation on my part, because I have no idea what these tables do, only that since there are parameters in min and max and they also represent volts, it sounds like the sensor offset calibration.

[chuck peterson]

sigh....make electricians since 1929..

Great discussion guys, thanks for the entertainment!

[Moto]

I understand what you have reported, but can't help with your questions.

I think you may be letting theory and programming get too far ahead your data. It's time to find out if your bike runs better at altitude without the white plug (or filter). If it doesn't, then this theorizing about the pressure sensor is probably not going to lead to a solution.

Moto

[Kiwi_Roy]

Have you tried out the ECU at altitude without the white plug yet?
If I read right the white plug is in the case, so it has a considerable volume to fill
The Guzidiag display reads 1042 mbar but you say your ambient pressure is 1015 - 1020 so it seems to be over the top of the correction curve.
Perhaps it might be interesting to attach a tiny hose to the port and change the pressure slightly while riding to see if the bike runs better, I think you would want to decrease it rather than increase.
You might find some interesting information on this site http://www.myecu.biz/MyECU/index.htm

[Elmelo]

Yesterday I went out to test the bike, without the plug I reached 2,600mts and there is an obvious improvement in the response of the engine, still running with the GCE3901 software. Before closing and sealing the lid of the ecu, I did some checks and tests, one of the tests was to verify that the sensor works, analogically speaking.
Identifying the pins of the sensor welded in the printed circuit was simple by having the datasheet, the device is square and has eight pins, of which only three are used, it has a notch in one of its corners to identify pin 1 that it is not used, the next pin is the 2, which corresponds to the power supply of the device + 5Volts, the next, pin3, this is the negative, and pin 4, is the output in volts that the device delivers depending on pressure Atmospheric existing at that time, pins 5, 6, 7, 8, are not used.




I don't have a barometer at home, so I check the data from the local weather service, 1,029mBar. With the ecu open, I take the voltage at the output (pin4) are 4,690 millivolts. In the characteristic curve of the device, I draw more or less the two lines whose point of intersection is over 103kPa, which corresponds to 1,030mBar, well it seems to work, I do not have the resources to do the same tests at different pressures, but I give it for good.




screenshot png to jpg

[Wayne Orwig]

I don't have a barometer at home, so I check the data from the local weather service, 1,029mBar. With the ecu open, I take the voltage at the output (pin4) are 4,690 millivolts. In the characteristic curve of the device, I draw more or less the two lines whose point of intersection is over 103kPa, which corresponds to 1,030mBar, well it seems to work, I do not have the resources to do the same tests at different pressures, but I give it for good.

Remember too, your local weather service will almost certainly be RELATIVE barometric pressure, not ABSOLUTE pressure. Relative pressure is not what you want. (unless you are at sea level of course)

[Elmelo]

Yes, I am at sea level and the test was done here, the sensor output voltage was 4,690mv which, according to the curve, corresponds to the pressure that is measuring 1,030mb which is the atmospheric pressure that was at that time . Which means that the sensor curve does not lie or what is the same, the sensor is measuring well.

[pauldaytona]

One more thing: the oldest 15m, the C1 uses anotehr pressure sensor then any other 15. So the maps that for are one the ones made for the c1 starting with GCE in the id.  Be it Quota or cali. But the quota software has otehr problems, the quota c1 ecu is ok as long as used with a c1 map like the GCE3901

[Elmelo]

One more thing: the oldest 15m, the C1 uses anotehr pressure sensor then any other 15. So the maps that for are one the ones made for the c1 starting with GCE in the id.  Be it Quota or cali. But the quota software has otehr problems, the quota c1 ecu is ok as long as used with a c1 map like the GCE3901

pauldaytona...Your answer is advanced to the question I wanted to ask  . The GCE3901 works very badly, I have gone crazy with all kinds of adjustments and nothing. I have two other softwares 3D02MM25 and 3D02MM26, with these two the engine works very well, better with 26. But these two softwares do not show atmospheric pressure data in the Diag, interestingly the pressure is shown when I blow or suck through the hole , if I suck it low, if I blow it up but only up to 1019mBar, which is what is preset in the "AirPressure_LimpHom eValue" scalar of the GCE3901. I guess it won't be as simple as copying the tables from a 3D02MM26 to a GCE3901.

[zelcovaa]

hello how are you, I would like to ask for your support in that someone share me the stock bin map, 3D02MM25 or 3D02MM26 maps, please my 2001 moto guzzi california special 1100, apparently it has faults in the ecu, and I need to reflash it. Thank you very much in advance