MS3X - R32 GTR install - help!

[drew6]

Hello all,

I am looking to install a MS3X system on an R32 GTR. I have a V3.0 MS3X built up for use with the stock CAS/sensors. I've seen a couple of people on here have done GTRs in the past so hopefully I can get some insight on two problems.

The problems both lie within getting the megasquirt unit to work with the ATTESA (AWD) system. It seems that the ATTESA computer needs only two inputs from the stock ECU to work. A TPS signal and rpm signal. From what I understand is the TPS signal is the raw data coming from the TPS (idle= .4 and WOT= 4.5V) and the tach input is the same signal that feeds the tachometer.

1) Regarding the TPS, according to DIYautotune, I need to "connect 330 ohm, 1/4 watt resistors from TPS VREF (pin 26) to both the low resolution signal and the high resolution signal to provide a pull-up in the wiring harness". If I add these resistors how will this effect the signal the ATTESA computer gets? (Assuming I spice the VREF directly to the MS and the ATTESA computer)

2) How do I get a proper tach output? I've searched but can not come up with a clear answer I understand.

Really appreciate any help.

[jsmcortina]

Connect the TPS signal to the AWD computer directly. The pullup resistors for the CAS should have no effect.

For tacho, see: http://msextra.com/doc/ms3/general.html#tacho

James

[nismoautoxr]

what James said on the TPS.

The CAS will report directly to the megasquirt and nothing else. Tacho out will go to your dash tach and to the ATTESSA ecu.

[drew6]

Thanks guys. I'm going to physically verify tonight (while the stock system is in place) that the AWD computer does get the raw data direct from the TPS, if this is the case and the pull-up resistors don't affect the signal than this is obviously a non-issue.

In regards to the tach output. I've read the linked page during my research but I thought the process was more involved than that. Does the standard MS3X tach output work with most stock tachometers? For some reason I had it in my head that getting it to work with most stock gauges took a lot more work than simply hooking it up and turning it on. Hopefully I'm wrong.

Andrew

[nismoautoxr]

depends on what tach you are using. If you are using the Nissan tach I can confirm that it just works without any extra circuits. If you have a negative coil triggered coil like a lot of older vehicles had then a lot of times it was necessary to built on of the circuits on that tach page.

[jasaircraft]

Hello i'm installing a ms3x 3.0 onto a r32gtr too.
Did you solve this issue?
According to my search a small circuit is needed to provide a modified tps signal to the attesa ecu.
Apparently
R32 and R33gtrs use a 2:3 scale of the raw tps signal
R34gtr uses a 1:1 scale.

I found a circuit diagram in a Link forum for this matter but the microprocesor they use is not available in my country.

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Anyone else having this issue?

[jasaircraft]

Maybe is there an analog ouput we could use?
So we have a table of tps vs voltage out

[Matt Cramer]

Maybe is there an analog ouput we could use?
So we have a table of tps vs voltage out

You could use a generic PWM output and a low-pass filter to get a signal out.

[jasaircraft]

Maybe is there an analog ouput we could use?
So we have a table of tps vs voltage out

You could use a generic PWM output and a low-pass filter to get a signal out.

Hello Matt, do you happen to have a diagram by any chance? so that would give a steady analog 0-5v voltage output not a pulse right?
i connected the stock ecu and saw the stock ecu receives and sends the same voltage both on tps in as in tps out.

[jasaircraft]

Hello, i was also doubting the following.
for the rb26 which has oem itbs ... should i select AlphaN for primary load and Speed Density for secondary load?

[Matt Cramer]

Hello Matt, do you happen to have a diagram by any chance? so that would give a steady analog 0-5v voltage output not a pulse right?
i connected the stock ecu and saw the stock ecu receives and sends the same voltage both on tps in as in tps out.

Not really - you're basically using a resistor and a capacitor. But if it's just following voltage, I would use the op amp circuit posted above.