convert oil pressure / CAt voltage to psi

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pbusanga
Posts: 38
Joined: Sun Jun 03, 2012 2:06 pm

convert oil pressure / CAt voltage to psi

Post by pbusanga »

i want to link a new parameter called OIL PRESSURE to the existing oil pressure / cat parameter in my mefi4.adx, which is in volts.

i have created the parameter and linked it to oil pressure/CAT, what formula should i use to convert volts to psi.

In the values for my new oil gauge parameter i set the range from low =0 to High= 100

i read somewhere that using a 0 - 100 psi gauge with 0 intercept i could use volts *20...does anyone know if i am on right track as i would like to have a gauge on my dash reading oil pressure in psi not volts.
pbusanga
Posts: 38
Joined: Sun Jun 03, 2012 2:06 pm

Post by pbusanga »

a formula which i see alot of for GM engines is psi= v*32 - 16 for a 0 - 5v sender....
cbernhardt
Posts: 95
Joined: Fri Apr 18, 2008 5:19 am

Post by cbernhardt »

pbusanga wrote:a formula which i see alot of for GM engines is psi= v*32 - 16 for a 0 - 5v sender....
I would think you would need to know the voltage that corresponds to an actual oil pressure reading in order to calculate a conversion factor. On your engine does 1v=20psi, 2v=40 psi, 3v=60psi ?

The MEFI4.adx conversion factor for the oil pressure/CAT is X*0.019531, which would be the voltage reading. If 1v=20 psi then the conversion factor would be X*0.019531*20 or X*0.39062

Charles
pbusanga
Posts: 38
Joined: Sun Jun 03, 2012 2:06 pm

Post by pbusanga »

not sure how i would find out what voltage corresponds to what pressure ? i was hoping there was some kind of standard for MEFI4.adx oil pressure conversion.

i created a new parameter (OIL PRESSURE PSI) and linked it to the original oil / CAT and then applied formula. Would it be better to use OIL PRESSURE as native , that is copy the original oil/cat and apply conversion directly to that.

i am new at this and learning so please bear with me.
cbernhardt
Posts: 95
Joined: Fri Apr 18, 2008 5:19 am

Post by cbernhardt »

pbusanga wrote:not sure how i would find out what voltage corresponds to what pressure ? i was hoping there was some kind of standard for MEFI4.adx oil pressure conversion.

i created a new parameter (OIL PRESSURE PSI) and linked it to the original oil / CAT and then applied formula. Would it be better to use OIL PRESSURE as native , that is copy the original oil/cat and apply conversion directly to that.

i am new at this and learning so please bear with me.
I would just add a new item named "Oil Pressure" and copy all the parameters from the old Oil Pressure/CAT item. That way you can look at both items on the dash board to make sure they read the same. After you make sure they are the same you can modify the new item to make it read in PSI.

I don't know if there is a "standard" oil pressure for the MEFI4. I think they were used on a variety of engines so that is why I suggested that you check yours with an oil pressure gauge to find out what voltage and pressures were equivalent. I assume your boat boat does not have an oil pressure gauge? Does it have an oil pressure sending unit?

If you cannot check it with a gauge, try the formula I posted earlier and see if it looks reasonable. At least it will tell you if the pressure drops drastically.

Charles
pbusanga
Posts: 38
Joined: Sun Jun 03, 2012 2:06 pm

Post by pbusanga »

Thanks Charles...quick question when you link new item cant you watch it on the dash along side the original item to check is same, then apply formula ??? same as you would with copying the native one and renaming it.

like i say i am new to this and my engine is not running so i cant test these for myself , i dont want to run it with out being able to check oil pressure when i start it up on bench.

Yes engine has oil pressure sender and boat has oil pressure gauge but engine is out of boat on bench. normal idling pressure should be around 40psi for my engine.
cbernhardt
Posts: 95
Joined: Fri Apr 18, 2008 5:19 am

Post by cbernhardt »

pbusanga wrote:Thanks Charles...quick question when you link new item cant you watch it on the dash along side the original item to check is same, then apply formula ??? same as you would with copying the native one and renaming it.
Yes you can.

Charles
pbusanga
Posts: 38
Joined: Sun Jun 03, 2012 2:06 pm

Post by pbusanga »

Thanks again ! Am beginning to get my head around this stuff. Cant imagine what it is like to get into actual tuning of engine..scary stuff !

I don't actually want to tune my boat engine just want to be able to monitor all its vitals and hope i can preempt any probs before i get stuck out at sea :)

thanks for all help.
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