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Discussion Starter · #1 ·
I found this Motorola sensor a few years ago, and I think It may be adapted to our bikes if we cannot locate a Pb or P2 sensor. Notice that this sensor is good for our bikes because it responds to pressure (from a turbo system), opposite of a normally aspirated car MAP sensor which uses vacuum, the opposite of pressure. Look closely at the scale of pressure to voltage output (it is metric, and needs to be converted). Now compare that to the book specs of the Pb sensor. May be close and need some tweeking, maybe by way of a restrictor plate or orifice tube of some sort, but gives us a possible alternative to the ever dwindling supply of specialty sensors on our beloved turbos. Hey, I might just order one, rig up a harness and experiment with it just to see if it is a viable option. Let's face it guys: we are going to have to consider some alternatives in the near future. I have kept a few failed sensor (Pb and P2) and may cut them open sometime and see about repairing it.

Here is the link to the Motorola MPX4250 2 bar sensor: http://www.datasheetcatalog.com/datasheets_pdf/M/P/X/4/MPX4250.shtml
 

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Some time ago I made an comparison between the Honda Sensors and the Freescale MPX4250







Using restrictors to match them is not possible. The only way is to electronicly convert the MPX4250 signal into the desired Honda input/output
 

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there must be an alterantive to the dwindling supply of 30 year old sensors,

i just got one of ebay but who knows how long it will last.

i must admit the therory is above my pay scale.

heres hopping a bright spark will find a suitable auto replacement.

mark
 

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The P1 and the PB sensor have exact the same output.



Has anyone tried to swap them ?



Theoreticly it should work............
 

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I just fixed my idling and low rpm (below 3000 rpm) surging issue by replacing the Pb sensor with a P1 sensor. They are interchangeable!
 

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So, if I am reading this correctly, the P2 and Pign are interchangeable, and the Pb and P1 are interchangeable.



Interesting, and pretty cool to know. As our sensor supply starts to dwindle, this may prove invaluable.
 

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So, if I am reading this correctly, the P2 and Pign are interchangeable, and the Pb and P1 are interchangeable.



Interesting, and pretty cool to know. As our sensor supply starts to dwindle, this may prove invaluable.


Warning : the Pign and P2 sensors are not interchangeable !!!!!!!!!!!!!!!!



Although the outputs are the same the voltage supply input isn't ! For the Pign it is a minimum of 8 Volt and for the P2 sensors it has to be between 4.75 and 5.25 Volt
 

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I was working on the design for the replacement of our sensors, but because the Ebay prices for second hand items are still relative low, I put the project on the backburner














 

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Discussion Starter · #12 ·
I was working on the design for the replacement of our sensors, but because the Ebay prices for second hand items are still relative low, I put the project on the backburner




















Wow! That looks awesome. I'm not sure I could design one, however, I think we could probably find an automotive unit and modify with a resistor board or something similar to make it work, if we had to. I'm thinking that maybe we can simply repair our sensor. I have not opened one up, however, if they are not epoxy sealed, then there may be hope to repair the unit. I'm sure it is just a variable resitor or pack or resistors and a small bellows of some sort. I think we should look into this as an option. Have any of you guys ever opened up a bad sensor and looked at it's internals? I intend to do that soon with my Pb sensor that is out of spec.......
 

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Discussion Starter · #13 ·
Some time ago I made an comparison between the Honda Sensors and the Freescale MPX4250







Using restrictors to match them is not possible. The only way is to electronicly convert the MPX4250 signal into the desired Honda input/output


Interesting. I'm wondering if installing an inline resistor pack to the output wire could make this work? It may take some math to figure the correct overall average resistance and voltage drop, but maybe.......hum.......are we on to something, Watson?
 

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This is a Pign Sensor I opened




On the left is the pressure sensor / pod ?? and on the right a kind of a resistor array which has been adjusted by removing material ( see white line in gray area )









 

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Discussion Starter · #15 ·
This is a Pign Sensor I opened




On the left is the pressure sensor / pod ?? and on the right a kind of a resistor array which has been adjusted by removing material ( see white line in gray area )













Good job on opening this one. Glad to know it's not sealed in epoxy like the ignition module on th 500T is supposedly. It looks like a standard small bellows and a printed circuit board. I'm thinking the small board can be removed and the resistors check for opens/shorts, etc, and then simply replaced. If the bellows is leaking vacuum, then it can probably be repaired with epoxy or sealant of some sort. This gives me hope that the sensor may be repairable and restored to useable condition.
 

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I have dissected the pressure sensor further










The pressure sensor "pod" , it looks like a kind of a wheatstone bridge congfiguration.

I decapated it with a Dremel tool, to my surprise 5 out of the 6 wires survived.

Photo taken through a looking glass






The other side of the small PCB, with several SMD components
 
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