Anyone know what the stock MAP sensor specs are? I.E. If its a 5v sensor, what = 0v and what = 5v. Also, does anyone know if its possible to replace it with a 2 or 3 bar gm MAP sensor? I'm asking because I have an LM-1 with the RPM converter and I have a 2 bar map sensor for pressure input for datalogging. If I can, I'd like to use the stock MAP sensor or replace it with one that has a larger range.
Stock MAP sensor specs
- Thread starter mixmastermatt
- Start date
Stock sensor is not a MAP type, it's an AFM, which outputs a frequency instead of a voltage.
The only way to replace it with a MAP sensor is to run an extra computer - like the MAFT Pro, MAP ECU, or full standalone.
The only way to replace it with a MAP sensor is to run an extra computer - like the MAFT Pro, MAP ECU, or full standalone.
I know what the 7M uses for metering air flow, but I'm not talking about the MAF sensor. I'm talking about the electronic MAP sensor, attached to a bracket, that is on the driver side of my car, next to the throttle control thing. There is a vacuum line going to a sensor that says "Toyota" and "Air Pressure Sensor" right on it. I want to know about that, not the Karmann Vortex MAF sensor.
dirgle said:
This much I assumed. I am wondering if anyone knows what the pressure vs voltage scale is, so I can use that with my logworks software.
Some pics, in case anyone else thinks I am talking about the MAF. I can see from the label plate that is is indeed a 5v sensor, so that question is answered. Also, does this sensor, in any way, affect any type of fuel cut parameters?
Oh! Sorry, my bad, that one hasn't been hooked up in my car for so long, I'd forgotten it existed. What I know about that one is rather limited, I'm afraid.mixmastermatt said:
Speaking of this sensor...does it provide any input to the ECU? Or is it strickly to the box that runs the guage behind the dash instrument panel.
Negative, the sensor doesn’t affect fuel cut; it only sends readings directly to the gauge.
ooo! Something I do know! This sensor is not connected to the ECU in any way, it only runs the boost gauge in the dash.
EDIT: Doh! Beaten by the dirgle again... /sniff...
EDIT: Doh! Beaten by the dirgle again... /sniff...
If anyone knows offhand the voltage/pressure scale, then that would help greatly. Otherwise, I'll just go out tomorrow and take voltage readings at different pressure levels. My plan is to make a new gauge face, calibrated to a 2bar map sensor. That way I don't have to worry about trying to fit my autometer gauge into the stock location, and I can keep the gauges somewhat matching. I can then also use the 2 bar for my logworks program.
dirgle said:
GrimJack said:ooo! Something I do know! This sensor is not connected to the ECU in any way, it only runs the boost gauge in the dash.
EDIT: Doh! Beaten by the dirgle again... /sniff...
Good to know...never really thought about it, but since I replaced the stock boost guage with a NA voltmeter...that means I can remove the sensor for under the hood.
It does beg another question...how does the stock ECU sense boost? Or is it just based on flow received from the AFM.
jdub said:
You got it. Along with air temp, and barometric pressure sensors.
mixmastermatt said:
I haven’t heard of anyone mapping the scale, however your idea is a good one, you will have to keep us up to date on your findings.
Here's my basic premise, in case anyone is confused as to what I intend to do.
Stock MAP sensor - ~0v = -4 on the stock gauge, ~5v = ~8psi
2bar GM MAP sensor - 0.02v = 29.1inHG, 2.45v = 0psi and 4.9v = 14.31psi
I can mark where the needle is at full scale, 2.5v and .02v from the stock sensor. Then I can create a overlay in photoshop that puts "14psi" at the full scale point, "0" at the midscale point and 29inHG at the .02v point. Then I'll fill in the gauge with 2psi increments. Then I'll just overlay the gauge with my scale, and replace the MAP sensor with the 2 bar sensor. Then I'll have a calibrated boost gauge for 2 bar. This will also work with a 3 bar, or any sensor as long as its a 5v scale.
Stock MAP sensor - ~0v = -4 on the stock gauge, ~5v = ~8psi
2bar GM MAP sensor - 0.02v = 29.1inHG, 2.45v = 0psi and 4.9v = 14.31psi
I can mark where the needle is at full scale, 2.5v and .02v from the stock sensor. Then I can create a overlay in photoshop that puts "14psi" at the full scale point, "0" at the midscale point and 29inHG at the .02v point. Then I'll fill in the gauge with 2psi increments. Then I'll just overlay the gauge with my scale, and replace the MAP sensor with the 2 bar sensor. Then I'll have a calibrated boost gauge for 2 bar. This will also work with a 3 bar, or any sensor as long as its a 5v scale.
Cool idea. The GM sensor appears pretty linear. Do you know if the Toyota sensor is linear too? I suppose if it is then 2.5V input should read about 2psi on the stock gauge.
3p141592654 said:
I'll find out tomorrow if its linear. Hopefully it is, I sort of doubt it is anything other than. I'll be using my air compressor and multimeter to map out the stock sensor's voltages.
I remember somone used the sensor on the ZTX wideband. It was something like 1.6psi to 1psi on the ztx logs or was it the other way around. Search for ztx and you will find it.
Do you want the output of the sensor or the output of the drive circuit? I'm not sure I follow the need for a new sesnor when you can rescale the drive circuit. You'll still need a new overlay of course.
I think the stock pressure sensor is good to 2 bar, maybe it was less, in any case, it's much higher than 8psi. There was a site on how to modify the stock gauge both to show higher boost and to react faster, both while using the stock pressure sensor.
jetjock said:
Which would be easier: rescale the drive unit or just replace the sensor? I know I can get to the sensor easier. Plus, I can use the GM sensor as my pressure sensor for my LM-1 and boosted SAFC tune. I know the voltage scale for the GM sensor, not so much for the stock one.
The scaling can be as easy as just a single potentiometer. It depends on the impedance of the stock gauge. If it is high like a voltmeter, which would seem the most likely, then a 10k or 100k potentiometer with the wiper contact going to the gauge, and the pot winding going from the sensor to ground would be all that you need. You would probably want that even with the GM sensor since it would allow you to calibrate the gauge accurately to your new expanded gauge scale.
If the gauge behaves like a variable resistor, for example like the coolant temperature sensor, then an op-amp based circuit would probably be required. Still pretty easy to do.
Does anyone have further info on the circuit that implements the delayed response of the gauge?
If the gauge behaves like a variable resistor, for example like the coolant temperature sensor, then an op-amp based circuit would probably be required. Still pretty easy to do.
Does anyone have further info on the circuit that implements the delayed response of the gauge?