The R201 resistor change

[Jonas_R]

I want to make sure I understand this correctly.

The resistor is on a voltage divider, that's on the MAF voltage.
Yes, the RS2 has a larger R2 in the voltage divider so the ECU can read higher MAF voltage.

So I can simply change the R201 resistor on my AAN ECU and then it will not effect the map in any way except that ECU can read a higher MAF voltage?

[S2central.net]

You only change R201 to line up with the ECU software.

AAN & ABY software uses one value
ADU/RS2 uses a different value

You cannot mix and match them

[prj]

Exactly.
If you change the resistor you will need RS2 software as well.

[UrS4boy]

You only change R201 to line up with the ECU software. AAN & ABY software uses one value,ADU/RS2 uses a different value.
You cannot mix and match them

I thought prj and the forum (maybe just me) went around on the need for this resistor recently (last month or so). I am running RS2 hardware (MAF, turbo, injectors, exhaust cam, exhaust manifold, 3 Bar MAP sensor in the ECU) with MRC Stage 3 software, making 288 whp (DynoDynamics dyno/rolling road) from my AAN yet there was no change in any resistor in the ECU. Just the new chip set and the MAP sensor. I don't see the big deal to change the resistor.

[prj]

The resistor change is required to run RS2 software.
As I explained in PM, without the resistor change the MAF value the ECU sees maxes out before the MAF itself maxes out.

Without the resistor change:
a) More of your engine is mapped to the last cell
b) You can not use RS2 software, which is much better than pre-551C AAN.

Yes, you can map the engine to the last cell, but the MAF value the ECU sees will max out at 330hp or so instead of 350hp.
Anyway, hp is an approximate. Without the resistor change I manage to max the MAF value that the ECU sees on my 1.6 bar Stage1+ chipset at 4000 rpm.

[Jonas_R]

well if his software is not rs2 then changing the resistor will effect the map how?

[prj]

well if his software is not rs2 then changing the resistor will effect the map how?

Timing, fuelling... hell, everything will be wrong.
To take advantage of the MAF range requires a remap.

[UrS4boy]

well if his software is not rs2 then changing the resistor will effect the map how?

My software is Stage 3 MRC = RS2 plus (350 plus crankhp) levels. Nobody in North America who has gone for RS2 equivalent hardware with after market software (MTM, MRC, 034, some home brew combos, etc) has changed this resistor yet they are making between 350 and 370 crank hp. I am not saying that the resistor change won't improve things but not changing the resistor has not caused any serious loss of potential power, as far as I can tell.

It would be likely be better to tune a car with the proper voltage divider to maximize the flow range of the MAF signal to the ECU. However, it is also likely NOT a good idea to change the voltage divider circuit by changing the resistor on ECUs running "RS2" software that was developed and calibrated to the stock circuit. Changing the resistor would require a complete remapping.

"IF it ain't broke, don't fix it"

[Jonas_R]

Thanks for clearing that up guys

[prj]

My software is Stage 3 MRC = RS2 plus (350 plus crankhp) levels. Nobody in North America who has gone for RS2 equivalent hardware with after market software (MTM, MRC, 034, some home brew combos, etc) has changed this resistor yet they are making between 350 and 370 crank hp. I am not saying that the resistor change won't improve things but not changing the resistor has not caused any serious loss of potential power, as far as I can tell.

Not at that power level, no.

It would be likely be better to tune a car with the proper voltage divider to maximize the flow range of the MAF signal to the ECU. However, it is also likely NOT a good idea to change the voltage divider circuit by changing the resistor on ECUs running "RS2" software that was developed and calibrated to the stock circuit. Changing the resistor would require a complete remapping.

Absolutely.
Changing that resistor with software not meant for it will cause lean mixture and advanced timing, since the ECU will read the MAF lower.
And we all know that makes stuff go boom.