Greddy 4 bar map sensor with stock connector!
05-11-09, 02:36 AM
#1
Greddy 4 bar map sensor with stock connector!
So I've been needing a 3 bar map sensor so I can start tuning for higher boost. Awhile back my Greddy Profec e-01 stopped working, and I thought.. I wonder if I can use the map sensor from the e-01 in place off my stock sensor? So I tried to find information on it and found very little except it's a 4 bar sensor, the part number is 16401301 and runs $116.
Originally I was just going to splice the harness and hook the wires up directly. (taking a guess at which wire goes where) Well when I went out to do some testing, I found that the connector on the map sensor will plug directly into the stock harness! So I plugged it in and it registered like 1v, but it wouldn't change with vacuum or pressure. I tested the stock harness' wires and It's:
green/yellow = Signal
Brown/White = 5V
Black/Grey = Ground
The stock orientation of the greddy harness (red,white,black) makes the black wire line up with the signal wire (G/Y), this was an obvious issue as black is almost always ground, so I removed the pins, from the e-01 connector. This took a little patience to figure out, and I just switched the white and black pins around with eachother. And it works now! Pressure/vacuum changes the voltage up and down as it should. Now I just need to get the correct scale and offset with a bit of testing.
How to remove the connector pins from the greddy connector:
In order to remove the connector pins from the greddy sensor, the yellow plastic connector thingy inside the connector has to be pulled out from the front. I'm not sure the proper way to do ethis, I ended up getting out on accident by pushing a tiny screw driver(slightly larger then a large needle) through one of the holes on accident, it came out attached to the screwdriver. This revels some small black retaining clips, I just slid the small screwdriver behind them, then pushed with another screwdriver on the individual clips until they popped out the back of the connector. This only needs to be done to the black and white wires, switch them around and put the yellow connector back. Done.
This might be a good alternative to the expensive apexi, or the GM w/ adapter harness, or for someone that wants to run huge amounts of boost.
Originally I was just going to splice the harness and hook the wires up directly. (taking a guess at which wire goes where) Well when I went out to do some testing, I found that the connector on the map sensor will plug directly into the stock harness! So I plugged it in and it registered like 1v, but it wouldn't change with vacuum or pressure. I tested the stock harness' wires and It's:
green/yellow = Signal
Brown/White = 5V
Black/Grey = Ground
The stock orientation of the greddy harness (red,white,black) makes the black wire line up with the signal wire (G/Y), this was an obvious issue as black is almost always ground, so I removed the pins, from the e-01 connector. This took a little patience to figure out, and I just switched the white and black pins around with eachother. And it works now! Pressure/vacuum changes the voltage up and down as it should. Now I just need to get the correct scale and offset with a bit of testing.
How to remove the connector pins from the greddy connector:
In order to remove the connector pins from the greddy sensor, the yellow plastic connector thingy inside the connector has to be pulled out from the front. I'm not sure the proper way to do ethis, I ended up getting out on accident by pushing a tiny screw driver(slightly larger then a large needle) through one of the holes on accident, it came out attached to the screwdriver. This revels some small black retaining clips, I just slid the small screwdriver behind them, then pushed with another screwdriver on the individual clips until they popped out the back of the connector. This only needs to be done to the black and white wires, switch them around and put the yellow connector back. Done.
This might be a good alternative to the expensive apexi, or the GM w/ adapter harness, or for someone that wants to run huge amounts of boost.
05-11-09, 10:41 AM
#3
With a MityVac it is pretty easy to work out the scale and offset for any MAP sensor for the PFC:
The PFC calculates absolute pressure in kg/m2 directly from the PIM sensor voltage. The calculation is:
PIM = scale * PIMV + offset
The PFC displays gauge pressure in kg/cm2, which is calculated in the usual way by subtracting standard atmospheric pressure (10332 kg/cm2) from absolute pressure and scaling:
Gauge pressure = (PIM - 10332)/1000
Gauge pressure is what the Commander displays as boost, and is also what the Datalogit logs in its boost column, though inexplicably multiplied by 100.
To calibrate a map sensor one needs to determine both scale (how the sensor reacts to pressure change (measured in kg/m2/V)) and offset (the number required to zero the gauge at local atmospheric pressure, measured in kg/m2).
Assuming linear response away from the edges of the PIM sensor's range, scale can be calculated by taking two non-edge voltage values 1 volt apart (say, 2 and 3 volts) and subtracting the two PIM values corresponding to those values. Offset is simply the number required to zero the gauge at local atmospheric pressure.
PIM = scale * PIMV + offset
The PFC displays gauge pressure in kg/cm2, which is calculated in the usual way by subtracting standard atmospheric pressure (10332 kg/cm2) from absolute pressure and scaling:
Gauge pressure = (PIM - 10332)/1000
Gauge pressure is what the Commander displays as boost, and is also what the Datalogit logs in its boost column, though inexplicably multiplied by 100.
To calibrate a map sensor one needs to determine both scale (how the sensor reacts to pressure change (measured in kg/m2/V)) and offset (the number required to zero the gauge at local atmospheric pressure, measured in kg/m2).
Assuming linear response away from the edges of the PIM sensor's range, scale can be calculated by taking two non-edge voltage values 1 volt apart (say, 2 and 3 volts) and subtracting the two PIM values corresponding to those values. Offset is simply the number required to zero the gauge at local atmospheric pressure.
05-12-09, 03:09 PM
#7
That is true, and i considered that before putting it on. I'm not sure how much of an issue that is, if any. It doesn't seem to have any negative effect on the car so far. Although i haven't tested it much, and i need to retune it slightly as i also increased my fuel pressure a few days before the map sensor change. Just changing to the 4 bar map sensor actually made the car idle better even though it was in the same rows. I can't explain this. I'm running manual idle control, and thought that maybe having less resoluition made the the computer not react as much between slight vacuum fluttations giving a smoother idle. I really have no idea. I'll post back after i have more seat time with the setup.
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06-02-09, 03:06 AM
#10
Been running the greddy map sensor for a couple weeks now. Boost is at 20 psi. It seems to work just as well as the stock one, no problems with the map I was already running. No drawbacks due to a reduced resolution. My maps have been rescaled to have less resolution at lower boost and this seems fine as well. Lets see if I ever get brave enough to max the map sensor out. (45 psi) ha ha
04-07-15, 06:45 PM
#11
thanks,
George
04-11-15, 07:32 PM
#12
It's been almost 6 years since I figured out the scale and offset for the 4 bar. I don't remember the process I used to get the numbers. I remember using a mityvac and checking the voltage vs vacuum readings. Sorry I can't be more help.
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