Nissan ECU Tuning

cb_drift · Joined: 04 May 2004 Posts: 472 Location: New Zealand

whats the wiring side of things look like?

do you just hook up two airflow meters and bridge their signal wires?
or use only one afm signal?
or do you have to run some sort of signal processor that takes two incoming signals and adds them together and then 1/2's the result to send to the ecu?

theres a program out from Eric i think that does all the calcs needed to the rom for running dual mafs - but im interested in how the physical wiring works out - as this system would of course work on any nissan single afm ecu and could solve some issues with afm limits on more extreme cars....
(or not so extreme cars where the owner is a tightwad Razz

)

and if Eric could link to his program from here that would be cool - or give a rundown on what changes and why for the K val etc that would be cooler Smile

eg change K by x because two afm's do blah to signal - or change vq map by 1/2 or something...

apart from the ecu having two physical inputs - how different is the gtr method of dual afm's?

romdoc1 · Joined: 03 Nov 2004 Posts: 29

CB one way to accomplish the dual maf set-up would be to plumb one maf right behind the other. Then all you would need to do is modify your K value to suite for dual Mafs. That's it. One other thing to note is that it really works better with larger than stock injectors.

By the way I am basising my arguments here on the dummy secondary maf ste up, that means no additional wiring.

Eric · Joined: 17 Nov 2003 Posts: 258 Location: Holland

>> do you just hook up two airflow meters and bridge their signal wires?

easiest way is to use an Apexi AFC/Neo
it will support input of two AFM's and will have 1 signal output.
You can have the Apexi add or average the signal of the AFM's

>> and if Eric could link to his program from here that would be cool

http://300zx-twinturbo.com/temp/rom_rescale.1.1.exe

>> or give a rundown on what changes and why for the K val

2 intakes, 1 afm: K x 2
2 intakes, 2 afm + AFC in ADD mode: K x 1
2 intakes, 2 afm + AFC in AVG mode: K x 2

this only applies to twinturbo setups, with seperate intakes

>> apart from the ecu having two physical inputs - how different is the gtr method of dual afm's?

it basically does the same as the AFC, but it's internally handled by the ECU.

>> as this system would of course work on any nissan single afm ecu and could solve some issues with afm limits on more extreme cars

my own preference is to ditch the AFM(s) and use a MAP sensor setup instead...it is a more reliable option (IMO)
The Nissan AFM's are very sensitive to air swirls and turbulence and these false reading can cause screwed up AFR levels.
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cb_drift · Joined: 04 May 2004 Posts: 472 Location: New Zealand

and that is why i like this place Smile

ask and get exactly what your after Smile

cheers for that Eric Smile

The_S_Man · Joined: 21 Apr 2006 Posts: 19 Location: Arizona

bazza1600 · Joined: 15 Dec 2004 Posts: 13 Location: nz

wont work by itself as it doesnt know the air volume - just the pressure - get a tmap from a new mini - temp compensated map sensor - but its only good for very low boost and na cars really... not heard of anyone trying one yet on a nissan either

Jollwah · Joined: 22 Nov 2007 Posts: 23

Have been thinking about this quite a bit lately.

Have been searching for a simple voltage averaging circuit without much success.

have come up with this, but I am not a 100% sure it would work. I'd try to prove it before using it.

AFM 1--------/\/\/\/\-----I
10 Ohms I
I------/\/\/\/\------ to ecu
I 5 Ohms
AFM 2--------/\/\/\/\-----I
10 Ohms

The resistor values a examples only and I have only put them in to show the relationships between the resistors.

This would increase the impedance of the circuit and I was thinking that this maybe accounted for by adjusting the K value to suit.

I have no idea if this is even going to work satisfactory but I would try it before buying SAFC neo or whatever to ave. AFM voltages.

If anyone has tried this and it didn't work please post a reply and save me effort of proving this with dummy circuit and variable voltage sources etc.

regards,
nathan

Jollwah · Joined: 22 Nov 2007 Posts: 23

Er that didn't work.

try this sorry about my artistic skills, I have none.

http://www.fast-files.com/getfile.aspx?file=4982

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nzniggles · Joined: 26 Aug 2006 Posts: 56 Location: New Zealand

Probably a very random result with that circuit as one AFM would load the other then you have to factor in the ECU. The only real way would be an op-amp adding circuit.

deviousKA · Joined: 14 Jun 2004 Posts: 107

Jollwah · Joined: 22 Nov 2007 Posts: 23

Eric · Joined: 17 Nov 2003 Posts: 258 Location: Holland

>> A VE table can even be autoplotted while in MAF based mode if an extra ADC channel is available and streamed through consult (allowing both MAF and MAP input at same time).

on a 300ZX ECU it is possible also.
You can use the fuel temp signal for the map sensor. (you will have to modify some code though).
In the original configuration the fueltemp sensor signal is barely used and disabling it in the code doesn't make any difference to the driveability of the car.
I use it as an extra 0-5V input very frequently

>> This would increase the impedance of the circuit and I was thinking that this maybe accounted for by adjusting the K value to suit.

>> I have no idea if this is even going to work satisfactory but I would try it before buying SAFC neo or whatever to ave. AFM voltages.

it won't work.
it's not a matter of just averaging the signal of the 2 afm's electronically...been there, done that and doesn't work

at low load the voltage will be too small, causing the ECU to throw a DTC error
Even after modifying the code handling the AFM, it didn't work correctly

you will need a cpu and a lookup table (similar to the VQ map), which looks up the voltages of the AFM's and output a voltage that is stored in the lookup table.
This is also how the Apexi AFC/Neo works.
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