Will An Aftermarket Engine Ecu Affect Attesa?

[3Katz]

Done lots of research and found lots of conflicting info and most of it fairly old so thought I'd ask specifically what I'm after. I have a RS4S Stagea (factory manual, NEO engine) and am after a good ECU to enable tuning with the parts I've collected (highmount 3076, GTR cooler, FFP etc). What I need to know is does the ATTESA (I believe RS4S is the same as R33 GTR) system use information from the engine ECU or is it totally independant using G sensors and wheel speed only? An aftermarket ECU to suit a NEO may not have ATTESA outputs and a GTR ECU would have ATTESA but not VCT function (plus wanting 2 AFM inputs). Was wanting an easy plug in ECU but it's looking like it may not be that easy....

[sydking]

ATTESA runs of its own ECU, like you said it uses G sensors to transfer power to the front wheels.

[3Katz]

ATTESA runs of its own ECU, like you said it uses G sensors to transfer power to the front wheels.

So it doesn't use a throttle position signal at all? I wondering what might happen say negotiating a hard corner while under brakes, although there is no power being delivered to the transmission the G sensors will still activate the clutch pack in the transfer case?

[GTSBoy]

Just Nistune your existing ECU. That's the easiest option. Tuneable enough for what you want and zero other problems.

[3Katz]

Just Nistune your existing ECU. That's the easiest option. Tuneable enough for what you want and zero other problems.

Thanks, I considered that but the NEO head on the 25 block will be a temporary thing as I would like to build a 30 bottom end and squeeze a fair bit out of it. Obviously the 3076 would have to go but the plan is to put money only into the top end at this stage so I can swap everything onto the new block and add bigger turbo. I'd like to have the ECU side of things sorted prior as well if possible...

[GTSBoy]

Nistune will run a NeoRB25/30DET no problem. It's still an easy solution for you. The only hassle is needing to retain an AFM, but that's not a huge obstacle these days either.

[3Katz]

Ok thanks that's definately worth thinking about further. Am still wondering if ATTESA requires info from the engine ECU though, even if just out of interest. Anybody know?

[GTSBoy]

I don't know the details of what is sent from ECU to ATTESSA computer, especially on the later ones. I do know that the vehicle speed sensor signal is passed to the ATTESSA computer, but I don't know if it is output from the ECU or if it is direct from the speedo. I would guess that it is direct from the speedo.

TPS is unlikely to be used by ATTESSA. The G-sensors are exclusively connected to ATTESSA.

PLUS......many people have run many GTRs and Stageas with aftermarket ECUs without having problems with ATTESSA. That would tend to suggest that the ATTESSA computer is not particularly fussy about the ECU.

I do know that the R34 (as an example) ECU will crack the shits at you if you try to run it without the ATTESSA and ABS computers that it expects to see. Will raise fault codes and CEL, and ultimately will interfere with engine operation if you try to make lots of power without the other computers there. I suspect this behaviour is pretty much one way traffic, and that you'd be fine to have the ATTESSA and ABS computers there without the factory ECU.

The trouble with all this theory is that the various computers are connected to each other on a serial bus. So there's not easily findable/probe-able pins carrying discrete signals. When they talk to each other, they just send messages on the bus. Makes it hard to know for sure.

[3Katz]

Ah thanks mate, good info, just what I was after. The speed signal coming direct from the speedo definately rings a bell now that you mention it. Yes I find these systems tricky to figure out I deal with CAN bus and CAT data link a bit through work and it definately pays to ask around before cracking out the schematics as someone has likely been down the same road before. Cheers

[blind_elk]

When I fitted a Stagea engine to my R32 GTS4, I also added a Wolf ECU (wired in, not PnP). Then, when the engine fired up - "Houston, we have a problem" - no AWD.

The ATTESSA ECU gets a TPS signal via the ECU. Solution was a "black box" add-on from Wolf.

I suspect if you get a PnP ECU, then you shouldn't have problems with ATTESSA.

[3Katz]

When I fitted a Stagea engine to my R32 GTS4, I also added a Wolf ECU (wired in, not PnP). Then, when the engine fired up - "Houston, we have a problem" - no AWD.

The ATTESSA ECU gets a TPS signal via the ECU. Solution was a "black box" add-on from Wolf.

I suspect if you get a PnP ECU, then you shouldn't have problems with ATTESSA.

This is interesting... I posted this question in the Stagea section as well and KiwiRS4T said he thinks he had to to a similar thing when installing his G4 in his series 1, out of interest is your engine a NEO or the R33? I think G4 is PnP right?

[GTR_JOEY]

Yes an aftermarket ECU can affect your 4WD and stop it from working..

I know with a Link ECU something needs to be done to make sure your 4wd works

[blind_elk]

This is interesting... I posted this question in the Stagea section as well and KiwiRS4T said he thinks he had to to a similar thing when installing his G4 in his series 1, out of interest is your engine a NEO or the R33? I think G4 is PnP right?

The engine was a C34, I believe (I did the conversion in 2004). I was told - after the fact - that I could have used a GT-R PnP from Wolf ECU.

[3Katz]

Thanks guys that's good info, very interesting. I have a PFC from a GTT here somewhere and that's why the question initially crossed my mind. Being for a RWD vehicle it may not have the TPS output. It's possible that it does have the output say the same as a GTR version but it's just not utilised in a non 4wd vehicle. Others have used the same ECU in a Stagea and say 4WD works ok I guess the easiest way would be to plug it in and see but that would mean getting a tune which would be a waste if I wasn't going to use it, food for thought.....