Motec M8 In R33 Gtr

[CameronBNR32]

I gave up on the idea of running it standalone.

The Motec can drive the tacho itself, but the problem is the TPS signal that goes to the ETS computer, the ATTESSA output.

You need to make a little circuit and the settings for the M800 are:

Setup the m800 output as function 3 – Aux Table.

Parameters –

Frequency = 10000Hz

Polarity = 1

Output Mode = 0

Set the table axis to Throttle Position.

When all connected, test with a multi meter. You should see voltages like this.

0% in the table should be ~0.5V

50% may only be ~1V

100% should be > 5V

no problem if your running a M800, but on the M8 the highest frequency I could put in was 1000hz, and I also ran out of outputs, I needed 1 x tacho output, 1 x tps signal, 1 x fuel pump, 1 x thermofan, 1 x boostcontroller, 1 x shift light. M8 only has 4 outputs, M800 has 8.

I am currently rewiring my whole engine loom to run the M8 with the stock ecu again.

[CameronBNR32]

Nearly finished off the loom today, but I ran into one problem...

Wiring up the crank angle sensor's power....

The crank angle sensor power runs at 12v (battery voltage) in the factory setup...

But the Motec wiring diagram has it wired up to 8v supply.. it was wired up on 8v before and working (running), but I need to wire the crank angle sensor signals into the factory ECU and into the Motec both at the same time...

Should I wire it up to 8v? or 12v? just worried about the factory ecu will not read it properly on 8v supply....and vise versa with the Motec with it at 12v supply

[R32 TT]

Well I can tell you that my CAS is running off the stock ECU at the moment and therefore 12v supply to it. I have it wired to both the Motec and stock ECU - no problems. It was also suggested to me that it is good to run the 'clean' regulated 8v out of the Motec to power the CAS. But I haven't tried this to see what the standard ECU thinks about that...

Where did you get the info on the circuit required as a matter of interest?

[CameronBNR32]

Thanks for that info.

I got the circuit diagram and infomation from Marck McCoy who works for Motec, he has been very helpful, I can forward you his email address if you wish?

[R32 TT]

Ah ok thanks mate, I speak to Mark from time to time. Very helpful guy at Motec. I'll have to look into this.

Can you not safely just give the TPS signal directly to the ETS computer as it is?

[CameronBNR32]

I thought that you could just tap into the existing wire aswell, but apparently not, I do not know why...

[rob82]

Differning sensor ground impeadance between motec and ETS.

You will end up with a floating TPS.

[R32 TT]

Differning sensor ground impeadance between motec and ETS.

You will end up with a floating TPS.

ok, but at the moment the TPS is shared between the standard ECU and Motec..? So could you not delete the connection to the std ECU and instead run it directly to ETS? ie let ETS and Motec share this one sensor?

Otherwise I assume what I have now 'should' not be working..? But how else do you get you TPS signal to both Motec and the std ECU?

(I hope I haven't just asked a really dumb question.... there is something about it which makes me think I have..)

[rob82]

ok, but at the moment the TPS is shared between the standard ECU and Motec..? So could you not delete the connection to the std ECU and instead run it directly to ETS? ie let ETS and Motec share this one sensor?

Otherwise I assume what I have now 'should' not be working..? But how else do you get you TPS signal to both Motec and the std ECU?

(I hope I haven't just asked a really dumb question.... there is something about it which makes me think I have..)

It depends upon the internal impeadances - if they are both relativly large then it wont really be an issue sharing the TPS signal. It is not good practise though. I worked for a company that made a tuning device that interfaced with various factory sensor's both analog and frequency based and impeadance matching was something we did on every vehicle.

I think that is what cameron was trying to get to with the Auxillary output - pretty much uses a frequency based signal with a cap to derive an analog output.