MAF sensor circuit
Nov 4, 2007, 11:04 AM
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MAF sensor circuit
Does anyone REALLY KNOW how the MAF sensor system operates in the RA? Everyone always speaks of frequency based this and karmen vortex that, does anyone have any solid research to back any of this up?
The reason I ask is that I am leaning more and more toward this being a traditional 0 to 5v sensor signal. No matter how the sensor actually measures the air, it still outputs a 0 to 5v signal according to all my efforts.
The tech manual states as much as well:
The reason I ask is that I am leaning more and more toward this being a traditional 0 to 5v sensor signal. No matter how the sensor actually measures the air, it still outputs a 0 to 5v signal according to all my efforts.
The tech manual states as much as well:
CIRCUIT OPERATION
The mass airflow sensor power is supplied from
the MFI relay (terminal No. 4), and the ground is
rate is sent to the ECM <M/T> or PCM <A/T>
sensor outputs voltage which corresponds to the
the voltage output by the mass airflow sensor
So I guess I am ultimately looking for someone to blame for all our woes
It would appear that we have been duped into thinking our options are limited. This also means that the guys who have the SAFC hooked up and are not posting may have it wired into the MAF signal instead of the MAP signal as that unit suggests.
I may wire up this SMT-6 as a 0-5v MAF system and see if I can't get it to tune the fuel. It won't do timing, but it would solve the problem I had getting it to work for fuel.
So a power supply, a ground, a 0-5v corresponding to airflow, and a 0-5v corresponding to air temp.
the MFI relay (terminal No. 4), and the ground is
provided on the ECM <M/T> or PCM <A/T> (ter-
minal No. 96).
A voltage that is according to the mass airflow minal No. 96).
rate is sent to the ECM <M/T> or PCM <A/T>
(terminal No. 63) from the mass airflow sensor
output terminal (terminal No. 3).
.
TECHNICAL DESCRIPTION
While the engine is running, the mass airflow output terminal (terminal No. 3).
.
TECHNICAL DESCRIPTION
sensor outputs voltage which corresponds to the
mass airflow rate.
The ECM <M/T> or PCM <A/T> checks whether the voltage output by the mass airflow sensor
while the engine is running is within a specified
range.So I guess I am ultimately looking for someone to blame for all our woes
It would appear that we have been duped into thinking our options are limited. This also means that the guys who have the SAFC hooked up and are not posting may have it wired into the MAF signal instead of the MAP signal as that unit suggests. I may wire up this SMT-6 as a 0-5v MAF system and see if I can't get it to tune the fuel. It won't do timing, but it would solve the problem I had getting it to work for fuel.
So a power supply, a ground, a 0-5v corresponding to airflow, and a 0-5v corresponding to air temp.
Nov 5, 2007, 08:51 AM
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it must be man, no other explanation 
If anyone has an oscilloscope please put the MAF signal on it
It CAN'T be a frequency signal, I'm not getting a 2.5v reading on the MAPECU2!!! If it was frequency based and you try to monitor it as voltage it should average as 2.5v (0-5v square wave) and it reads just like a 0-5v reading!!!
If anyone has an oscilloscope please put the MAF signal on it
It CAN'T be a frequency signal, I'm not getting a 2.5v reading on the MAPECU2!!! If it was frequency based and you try to monitor it as voltage it should average as 2.5v (0-5v square wave) and it reads just like a 0-5v reading!!!
Last edited by DangerousDan; Nov 5, 2007 at 08:54 AM.
Nov 5, 2007, 08:33 PM
#4
I tried scoping my MAF a year or two ago, I couldn't get the signal to change either voltage or frequency. It's possible I didn't have the scope set correctly, but not likely. I have used it to check waveforms and voltage before.
If it wasn't heading directly into winter here, I might be persuaded to try again. We'll see.
If it wasn't heading directly into winter here, I might be persuaded to try again. We'll see.
Nov 5, 2007, 09:32 PM
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this excites me in ways franks red hots can not......bad joke this is very interesting i might start researching this again as well. lets close this case with a definate answer if anyone has any valid ideas i will try it out with my SAFC II and just for kicks im going to call my mitsu dealers head mech he knows his stuff really well maybe ill try my only local performance shop that has a dyno since we have such a large quantity of Ralliarts here maybe odds will be in my favour. good luck guys lets git er done
now you really can change fuel!!
Nov 6, 2007, 02:16 PM
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so i understand what you are saying and if all your research is correct and i trust that it is then the SAFC II should just hook right up like it does in the book but that is not the case it barely runs and stalls out.....basically im asking if there is something that needs to be done differently when connecting the wires?
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Nov 6, 2007, 02:26 PM
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i wonder if it is something as simple as this...from another forum
So double checked all the wiring. Resoldered everything. Still starts up leans, out and dies.
So I decided to mess with the settings because I remember reading on here that some people had to change their settings cause SAFC II is weird like that sometimes. I changed the sensor from
2 in, 6 out which is what redtop SR with z32 is supposed to be
to
1 in 6 out
Now it idles fine. A little lean around 15. I havnt been able to actually drive the car because of the weather so I dont know how it does other then idle and revving it.
So double checked all the wiring. Resoldered everything. Still starts up leans, out and dies.
So I decided to mess with the settings because I remember reading on here that some people had to change their settings cause SAFC II is weird like that sometimes. I changed the sensor from
2 in, 6 out which is what redtop SR with z32 is supposed to be
to
1 in 6 out
Now it idles fine. A little lean around 15. I havnt been able to actually drive the car because of the weather so I dont know how it does other then idle and revving it.
Nov 6, 2007, 02:34 PM
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post up in your install thread, don't want this to go off topic too far as it's in the advanced forum but I need more information about the setup you are talking about.
one question though, you are saying you can't get it to idle with the SAFC on the MAF wire?
one question though, you are saying you can't get it to idle with the SAFC on the MAF wire?
Nov 6, 2007, 02:37 PM
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originally when i installed it about 3 months or so back it would not idle smooth at all and stall out after a while and it would stall out immediately if i revved the engine a little. so now im hooked to the map and its just a fancy guage that looks as though it has a function.
Nov 10, 2007, 09:42 AM
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well i went into the garage today to try some playing around and this is what happened so i tried out karman again and same old thing run rough like a struggle and stall out, then i went through every other sensor type and played with the sensor settings and they all gave an identical result the car started but then immediately shut down so i though well maybe ill see what happens if i give it some gas but that did absolutely nothing at all it was like the throttle wasn't even working any thoughts.....unless you can prove otherwise i think that our sensor is karman cause its the only thing i could get the car to somewhat run on.
Nov 11, 2007, 08:18 AM
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I wish someone who knew what was going on would post here. why can't I monitor a KVF signal with a unit that is supposed to use the same signals
two piggybacks I have tried, both with karmen capabilities, won't read or emulate the signal. **** 
two piggybacks I have tried, both with karmen capabilities, won't read or emulate the signal. ****
