slash128's Top Mount Build
#276
hurry up with the work stuff Slash. I'm over itching for some updates
#279
Driving my unreliable rx8
I did some reaserch, and have the parts for a variable voltage divider on order. Right now I am looking for a MAF extension cable so I don't have to cut my stock harness.
If anyone knows where to buy one let me know.
My minimum order was 10 pieces so If it works I have enough parts for 9 others.
If anyone knows where to buy one let me know.
My minimum order was 10 pieces so If it works I have enough parts for 9 others.
#281
Registered
Slash, how far away are you trying to mount your Maf? The Maf wiring is quite long, all you have to do is unravel it from the wiring loom and you will see that it goes all the way down to the main fuse box.
When I repositioned my Maf, I ended up with miles of spare wire, that I ended up folding in half and hiding under the main fuse box.
Rotaman
When I repositioned my Maf, I ended up with miles of spare wire, that I ended up folding in half and hiding under the main fuse box.
Rotaman
#282
Boosted Kiwi
iTrader: (2)
I did some reaserch, and have the parts for a variable voltage divider on order. Right now I am looking for a MAF extension cable so I don't have to cut my stock harness.
If anyone knows where to buy one let me know.
My minimum order was 10 pieces so If it works I have enough parts for 9 others.
If anyone knows where to buy one let me know.
My minimum order was 10 pieces so If it works I have enough parts for 9 others.
#284
Ref http://en.wikipedia.org/wiki/Mass_flow_sensor I would presume a well designed harness have close to zero voltage drop, you want the heated wire inside sensor to dictate as much as possible of current/voltage changes, not temperature in engine bay etc., as would be the case with undersized conductors.
#286
And if you want voltage over sensor to be really accurate, it's quite easy to compensate for conductor loss in regulator by adding a extra wire for feedback.
EDIT: Did not see your reply before posting this. Making a voltage regulator is usually quite easy DIY, but that might not be an option here. Do you want to change voltage to avoid ECU to saturate at this feedback? Do you have a schematic for this circuit? Then, for once, I might be able to contribute.
EDIT: Did not see your reply before posting this. Making a voltage regulator is usually quite easy DIY, but that might not be an option here. Do you want to change voltage to avoid ECU to saturate at this feedback? Do you have a schematic for this circuit? Then, for once, I might be able to contribute.
Last edited by AAaF; 10-13-2013 at 02:38 PM.
#287
Driving my unreliable rx8
4.69volts stock max-1.25 Volts=3.44 or about 135g/sec compared to 365g/sec at 4.69 volts. That's 230g/sec differance. I bet with the aditional slope we are looking at 700+ g/sec on stock MAF with 6.25 Volts.
Looking at the idle side of the map I idle around 1.33*.8 drops to 1.064 Which is a aweful close to those first two cells on the MAF scale. So Maybe a 15% decrease. 1.33*.85=1.13 puts it about 6 cells from the left. 5/.85=5.88 Volts Which I would say is 600+ g/sec.
Now When I get done changing the 16 Spark plugs on my wifes truck I'll check to see if the MAF is actually putting out more then 5 volts but the cobb/car is not registering it.
#288
Boosted Kiwi
iTrader: (2)
I think 20% would be plenty. 5 volts/0.8=6.25 Volts. So that's an aditional 1.25 Volts. Looking at the slope on the MAF calibration it would be a huge increase in flow.
4.69volts stock max-1.25 Volts=3.44 or about 135g/sec compared to 365g/sec at 4.69 volts. That's 230g/sec differance. I bet with the aditional slope we are looking at 700+ g/sec on stock MAF with 6.25 Volts.
Looking at the idle side of the map I idle around 1.33*.8 drops to 1.064 Which is a aweful close to those first two cells on the MAF scale. So Maybe a 15% decrease. 1.33*.85=1.13 puts it about 6 cells from the left. 5/.85=5.88 Volts Which I would say is 600+ g/sec.
Now When I get done changing the 16 Spark plugs on my wifes truck I'll check to see if the MAF is actually putting out more then 5 volts but the cobb/car is not registering it.
4.69volts stock max-1.25 Volts=3.44 or about 135g/sec compared to 365g/sec at 4.69 volts. That's 230g/sec differance. I bet with the aditional slope we are looking at 700+ g/sec on stock MAF with 6.25 Volts.
Looking at the idle side of the map I idle around 1.33*.8 drops to 1.064 Which is a aweful close to those first two cells on the MAF scale. So Maybe a 15% decrease. 1.33*.85=1.13 puts it about 6 cells from the left. 5/.85=5.88 Volts Which I would say is 600+ g/sec.
Now When I get done changing the 16 Spark plugs on my wifes truck I'll check to see if the MAF is actually putting out more then 5 volts but the cobb/car is not registering it.
But yeah , need to know if we can actually get more than 5v first.
#289
Driving my unreliable rx8
#290
Driving my unreliable rx8
#291
n3rd
Thread Starter
Slash, how far away are you trying to mount your Maf? The Maf wiring is quite long, all you have to do is unravel it from the wiring loom and you will see that it goes all the way down to the main fuse box.
When I repositioned my Maf, I ended up with miles of spare wire, that I ended up folding in half and hiding under the main fuse box.
Rotaman
When I repositioned my Maf, I ended up with miles of spare wire, that I ended up folding in half and hiding under the main fuse box.
Rotaman
#293
Driving my unreliable rx8
#295
n3rd
Thread Starter
That would be for a linear slope. Depending on the actual curve it could be capable of measuring much more at that voltage. Also, the curve is kinda wonky. It looks like a smooth curve in ATR but plotting the top end in finer resolution (or by looking at the values if you are good with numbers) reveals that the rate of rise drops off. At any rate, without flow testing against a known control value then I think (420/5 ) 5.63 = 472 works close enough and then we adjust with VE. If the MAF, in fact, reads higher than 5V
#296
Driving my unreliable rx8
That would be for a linear slope. Depending on the actual curve it could be capable of measuring much more at that voltage. Also, the curve is kinda wonky. It looks like a smooth curve in ATR but plotting the top end in finer resolution (or by looking at the values if you are good with numbers) reveals that the rate of rise drops off. At any rate, without flow testing against a known control value then I think (420/5 ) 5.63 = 472 works close enough and then we adjust with VE. If the MAF, in fact, reads higher than 5V
Agreed. I was thinking
.63volts
4.69volts=365 g/sec
4.69-.6volts3=4.06volts or 233g/sec
365g/sec-233g/sec=132differance
5.63-4.69=0.94volts/.63volts=1.49*132=196g/sec
196+365=561 and I think that's a little low.
#298
Driving my unreliable rx8
With the Key in the run position but the engine off.
A=11.66 Volts
B=Ground
C=MAF Signal
D=ground
E=5 Volts
D and E might be swaped I don't remember.
With the sensor pluged in I pushed volt meter probes into the back of the plug.
A to b=11.66 Volts
A to c=nothing
A to D=11.66 Volts
I did not put A to E becuse they are both positive.
B-c 0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
b-d nothing
b-e 5 Volts
c-a= I did not do because they were both positive
c-b=0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
c-d=0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
c-e I did not do this since they are both positive.
D-E= 2.12 volts(IAT when I blew compressed air the voltage went up. When I blew my breth it went down.
I Plugged the probes into c and b then blew compressed air directly into the MAF. The Volt meter showed 5.63 volts. The cobb showed 5 Volts.
Last edited by logalinipoo; 10-13-2013 at 11:02 PM. Reason: I missed one
#299
Boosted Kiwi
iTrader: (2)
When looking at the plug contacts on the wiring harness. there are 5 pins. Lets label them from left to right a,b,c,d,e
With the Key in the run position but the engine off.
A=11.66 Volts
B=Ground
C=MAF Signal
D=ground
E=5 Volts
D and E might be swaped I don't remember.
With the sensor pluged in I pushed volt meter probes into the back of the plug.
A to b=11.66 Volts
A to c=nothing
A to D=11.66 Volts
I did not put A to E becuse they are both positive.
B-c 0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
b-d nothing
b-e 5 Volts
c-a= I did not do because they were both positive
c-b=0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
c-d=0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
c-e I did not do this since they are both positive.
D-E= 2.12 volts(IAT when I blew compressed air the voltage went up. When I blew my breth it went down.
I Plugged the probes into c and b then blew compressed air directly into the MAF. The Volt meter showed 5.63 volts. The cobb showed 5 Volts.
With the Key in the run position but the engine off.
A=11.66 Volts
B=Ground
C=MAF Signal
D=ground
E=5 Volts
D and E might be swaped I don't remember.
With the sensor pluged in I pushed volt meter probes into the back of the plug.
A to b=11.66 Volts
A to c=nothing
A to D=11.66 Volts
I did not put A to E becuse they are both positive.
B-c 0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
b-d nothing
b-e 5 Volts
c-a= I did not do because they were both positive
c-b=0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
c-d=0.7-0.8 Volts.(the same the cobb showed for MAF voltage)
c-e I did not do this since they are both positive.
D-E= 2.12 volts(IAT when I blew compressed air the voltage went up. When I blew my breth it went down.
I Plugged the probes into c and b then blew compressed air directly into the MAF. The Volt meter showed 5.63 volts. The cobb showed 5 Volts.
When you blew air down it were you able to adjust the flow to get various voltages showing ?
#300
Driving my unreliable rx8
I don't remember the numbers.
With my breath it was about 2 volts.
Then I used the Air through a cheap blower fitting
20PSI and was in the 3 volt range
40PSI was 4.8 or so
60 PSI was 5.63
150PSI 5.63
When I did this I was holding the MAF sensor in one hand and the air hose in the other.