3 bar Map Sensors

[OhSoSlow]

Hi guys,

Does anyone know if theres a difference between a Motorola and GM 3 bar map sensor, in terms of Voltage etc? i.e. are they interchangeable, or would car need to be retuned?

Thanks.

[Locust2000]

They're different. Depending on ECU, you may be able to change the 'map' of the MAP sensor, otherwise it's a retune. If it's a retune though it shouldn't be a biggie because you can just manually scale the tables.
A side detail which i'm unsure of myself, but want to know, is if the Motorola 2.5bar is 2.5 or 3.5bar. Remember, a "3 bar sensor" is actually 4 bar, because 1 bar is atmosphere(0psi on most gauges).
Without bothering to lookup the actual reference voltages, lets pretend:

2.5BAR
Vacuum: 0.1V
0psi 1.43V
28psi: 5.0V

3BAR
Vacuum 0.1V
0psi 1.25V
42psi: 5.0V

Since the sensors return diff voltages for the same pressure, that's why your ECU's rom needs to be adjusted accordingly to compensate for that.

[OhSoSlow]

Yeah, I've got a 3 bar motorola, which is why I was thinking the voltage would be the same as the GM?!

edit: I got the car tuned yesterday, and the map sensor broke today, so not really looking forward to another big drive to get it retuned! :evil:

[hybrid_H]

how much boost are u running?

for low boost the factory map sensor will be fine uotp 11 psi :thumbsup:

[Bigelboe]

Locust, I thought they were measured in absolute scale? So a 3 bar sensor measures 1 bar of vacuum and two of boost? I could be completely wrong tho :/

[OhSoSlow]

It's running over 11psi, and has already been tuned for the motorola 3 bar.. so looks like I might have to get another one.. would prefer the GM as it looks a lot more robust..

[Bigelboe]

Apparently the Motorolla one is more accurate, and the tune will be slightly different between teh motorolla and the GM probably.

I just checked on the PGMFI wiki and Im pretty sure all map sensors are referred to in absolute pressres Locust, so a 3 bar reads up to ~29PSI of boost, not 42 psi?

[OhSoSlow]

Yeah, I seem to remember reading something about 29psi for a 3bar..

N bugger, best I bite the bullet and order another motorola, and pray it doesn't break too!

[Locust2000]

Originally Posted by Bigelboe

Apparently the Motorolla one is more accurate, and the tune will be slightly different between teh motorolla and the GM probably.

I just checked on the PGMFI wiki and Im pretty sure all map sensors are referred to in absolute pressres Locust, so a 3 bar reads up to ~29PSI of boost, not 42 psi?

I was always under the impression that they were rated in absolute pressure(makes sense) instead of 'pressure over atmospheric' (which doesn't make sense), but then when my mate who works at Holden(but he's actually a fairly bright spark himself) said that if they order a 3bar it's actually 3bar over atmo, not 3 bar total. I questioned him heaps about it, because he's not an idiot (and I dont think I am all the time) but that's how they listed them. Still seems weird to me.

[d16a7]

all the places ive read are 3 bar including 1 bar for atmospheric pressure..

and in reality if you are reading 3 bar above normal atmospheric pressure you have a 4 bar map sensor... (that is the simple logic i get from my Dive course booklet)

so yeah...

anyways...

[OhSoSlow]

A bit of an update, for future reference.. the motorola and GM 3 bar map sensors, ARE different.. so a retune is in order.. damn it all! :evil:

[doo0T!doo0T!]

Originally Posted by OhSoSlow

A bit of an update, for future reference.. the motorola and GM 3 bar map sensors, ARE different.. so a retune is in order.. damn it all! :evil:

Not with Hondata 8) You can just change the map sensor type by selecting from a list and if its not on the list you can test it and enter the voltage range and pressures manually.

p.s i drank your bacardi at new years ops:

[OhSoSlow]

Yeah, I think crome has a similar option .. still meant a drive back down to tauranga.. so have brought more parts.. will get it all done in one go.. need more power..

And you had bacardi for me? bastard..

[Locust2000]

Yeah crome has the same "choose a sensor" option and it'll adjust accordingly. Haven't had a chance to try it out personally tho.