MoTeC Global Forum

Hey all,

I am having dramas with a Motec M8 in a R33 GTR.

When I purchased the car it was running the Motec M8 and the standard ECU, the car is a ex Targa Tas car, and as I believe in the regulations the car had to be able to be run on the factory ECU and that is the only reason the stock unit was in the car.
Now after about 1 1/2 years I have rebuilt the car and rewired the whole loom with running the Motec as the standalone ECU, but...

The motor seems to be only running on 4 cylinders
All the injectors and ignition all work fine in diagnostics, but once started cylinder #4 and #6 do not work, it seems cylinder #1, #2, #3, and #5 are the only ones that work.

Cylinder 4 and 6 injectors are opening/closing while the engine is running.

I have now run out of ideas... I have checked/changed:

Spark plugs
Injector wiring
Injectors
Coil pack wiring loom
Coil packs
Ignition module
Ignition module wiring (IGN1, IGN 2, and IGN3)
Ignition coil firing pairing (1/4, 2/5, 3/6)
Crank angle sensor
Crank angle sensor wiring (8v, sync, ref, and ground)
Compression tested all cylinders 150psi

All were fine with no errors found.

I spoke a local well respected tuner today to see if they had any ideas or could look at the car with a scope and they said it is too difficult to get a Motec M8 to work on a I.T.B RB26 and I should be looking at another ECU... I don't understand how that is possible...

I am now thinking of getting the unit inspected/tested for any faults and flashed back to factory settings.

Anybody done this before? any ideas?

Thanks.

Hi Mate,
Definitely not too difficult to get that engine running on an M8, probably need to talk to a MoTeC approved tuner instead.

I assume this is the car we were talking about over dinner at the WTA? Get it to a dealer that has a scope to see what is going on. Also check that the injecotrs actually have voltage when the car is running.

Hey Mark,
I forgot to get your card when we where down there.

I have been talking to a couple of people that run Motecs in GTR's and I think we have found what I have done wrong.

I think I have wired the Ignitor's coil pairing wrong.

I went off drawing # M26 "Nissan 6 Cyl Coil on Plug" and paired Cylinder 1/4, 2/5, 3/6, but have since been told it should be 1/6, 2/5, 3/4.

If that is the case it would explain ALOT

Will rewire it this weekend and see how I go!

Thanks.

Good to know that a well respected tuner did not say this first, stick to people listed on our website otherwise someone will convince you that you need three webers and a 6/71.

Let me know if you need anything. My email is mark.mccoy@motec.com.au

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

The MoTeC will work with 5v, 8v or 12v it does not matter. In reality the sensor is switching the ECUs singal to ground and not to power. The inputs in the ECUs have a pull-up.

If you are wiring the REF/Sync to both ECU's then do not wire the REFPU & SYNCPU pins to 5V on the M8.

This will get rid of one set of pullup resistors.