AAn Ecu been socketed?!

[Jonas_R]

But the resistor change is only needed if you want to run RS2 software on ABY/AAN ecu right?

[prj]

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.

If you want to copypaste some RS2 chips, then yes, you need to change it.

[UrS4boy]

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. If you want to copypaste some RS2 chips, then yes, you need to change it.

PRJ: I presume you are talking about OE RS2 chips in the above statement (?). Is this necessary for aftermarket chip sets? I am running generic MRC Stage 3 (RS2 plus) chips on my RS2'd AAN (RS2 MAF, Turbo, injectors, Exhaust Cam, Exhaust Manifold) and did nothing with any resistor on the motherboard(s). Should I have?

[prj]

Yes, you should have, as you are running too rich all the time.
On idle and low-load it is corrected by the O2 feedback loop, but at moderate load and WOT you will always run rich with your timing retarded too far.

That one resistor change, will give you quite a few extra ponies.
Also, MAF doesn't matter. My AFR log is completely identical with AAN and ADU MAF. Accurate to 0.001 lambda.

[Jonas_R]

PRJ:

If he has a custom chip for S2/S4 with RS2 why would he then need that resistor? You just said it was only need if you run RS2 software and not custom.

[prj]

You should read better. He said he does not have a custom chip.
And even with a custom chip, you would always want to change that resistor during mapping, as otherwise you can't use the entire range of the MAF.

[Jonas_R]

You should read better. He said he does not have a custom chip.

I read just fine mate, and a generic RS2 chip from MRC is a "custom" chip in this regard. I would think that at some point someone mapped a S2/S4 with RS2 setup and used the data to make the generic chip MRC sells. Surely if the software was made for AAN/ABY ECU then changing the resistor would alter the mapping?

And even with a custom chip, you would always want to change that resistor during mapping, as otherwise you can't use the entire range of the MAF.

I would assume this only applies if you use the RS2 MAF?

[prj]

I read just fine mate, and a generic RS2 chip from MRC is a "custom" chip in this regard.

The ones I have seen aren't. Hard to say without seeing the sw.

I would think that at some point someone mapped a S2/S4 with RS2 setup and used the data to make the generic chip MRC sells. Surely if the software was made for AAN/ABY ECU then changing the resistor would alter the mapping?

It alters MAF signal. I already explained everything.

I would assume this only applies if you use the RS2 MAF?

You are saying you read just fine, yet you ask a question, which has been answered by me three posts ago

Also, MAF doesn't matter. My AFR log is completely identical with AAN and ADU MAF. Accurate to 0.001 lambda.

[UrS4boy]

You should read better. He said he does not have a custom chip.
And even with a custom chip, you would always want to change that resistor during mapping, as otherwise you can't use the entire range of the MAF.

I may have mis-used the word "generic". What I meant was the chip set was developed by Mihnea Cotet using somebody else's UrS4/6 AAN with RS2 hardware (MAF, turbo, injectors, exhaust manifold, etc.) as the input/output source. I said "generic" to signify that it was not a specific chip set developed with Mihnea sitting in my car, with his laptop, either on a rolling road dynamometer or doing multiple 3rd gear pulls on the backroads. My chip set came in the mail.

All that said, I presumed that he would have corrected the resistor issue through software if the OE AAN and RS2 MAFs outputs are the same (ish).

I have had my car dyno'd at 289 whp which based on a stock car on the same dyno on the same day translated into about 350 crank horsepower. On the same day, an UrS6 with exactly the same RS2 hardware as mine but Dahlback/MTM software did 298whp which seemed to make sense as 370 crank hp (or so).

[prj]

I may have mis-used the word "generic". What I meant was the chip set was developed by Mihnea Cotet using somebody else's UrS4/6 AAN with RS2 hardware (MAF, turbo, injectors, exhaust manifold, etc.) as the input/output source. I said "generic" to signify that it was not a specific chip set developed with Mihnea sitting in my car, with his laptop, either on a rolling road dynamometer or doing multiple 3rd gear pulls on the backroads. My chip set came in the mail.

All that said, I presumed that he would have corrected the resistor issue through software if the OE AAN and RS2 MAFs outputs are the same (ish).

I have had my car dyno'd at 289 whp which based on a stock car on the same dyno on the same day translated into about 350 crank horsepower. On the same day, an UrS6 with exactly the same RS2 hardware as mine but Dahlback/MTM software did 298whp which seemed to make sense as 370 crank hp (or so).

You can not correct for that resistor using software.
With the AAN resistor the vfc in the ecu clips before the maximum output voltage of the maf is reached. So your ecu can't read as high. That way you lose precision up high and have to map to the last cell. It is possible, but not the right way to do things.
Basically the only way to find out which resistor it is meant for is to look inside the software or ask minhea.

[Jonas_R]

I've also seen a few ecus myself and some later ones (let's call them series 2, ok? 551a = ser1) do have factory sockets. I haven't found a rule really. In some rare occasions they exist and still mostly not.
Dizzy ecus are indeed always socketed.

Can the 551AA be a dizzy ECU or is it only 551A that are a dizzy ECU?