Motec/sharing Ref/sync..

[R32 TT]

Just a question to anyone who has fitted Motec to an R32 GTR.

The "quick question" is:

Is there any problem sharing the signal from the Ref/Sync with both the factory ECU and Motec?

The "long version" of the question is:

I'll give you as much background as I can think of,

I have a Motec M800 and Motec CDI-4 running wasted spark on specific CDI coils. This has all only recently been fitted along with new turbos, injectors and so on...

The other day, the car ran up on a 2-wheel dyno without any issues and got a good horsepower result at 1.2bar

There was however an issue with voltage to the Motec - it was reading 17volts (I'm not sure how or why) - and so wiring was changed to make sure it had a good discrete power feed and it now get more like the 13.8 volts it should. This in turn changed the state of tune, and so it had to be mapped again. (although I am surprised at this as I would have thought Motec would have compensated for this?) Anyway, it seemed to behave a lot better now that the electrical gremlin was gone.

And this is where a NEW problem begins:

My tuner is experiencing an issue where the engine is cutting out at higher revs and with higher boost.

It sounds and acts like an ignition problem as cylinder pressures rise and we increase boost the problem seems more prevalent. But, we never had this issue before, and we doubt the CDI is incapable of lighting the spark. Even so we tried closing the gaps. It was a little hard to be certain because the RPM at which cut out occurs tends to move around a little and we haven't established a pattern... but the problem still exists.

The next symptom is that when the cutout happens, the Diagnostic LED on the side of the Motec CDI suddenly goes out. This diagnostic LED represents triggers to fire the coils and comes from the Motec ECU. To be sure that the CDI is working correctly, we pulled two spark plugs and ran the Diagnostics from the Motec software and basically ran the CDI up to 8000rpm and watched the spark plugs happily firing away.. (ie the engine is not running, we are simply driving the CDI from the Motec ECU, via the laptop diags) And so this shows that the Motec ECU trigger is working, and that the CDI is happily sparking away at 8000rpm.

Now the LED on the CDI flashes each time it has a trigger - so when it goes out, its implying that the Motec ECU did not trigger it. (the LED will flash whether or not we have 'enough' spark in the cylinder as the CDI does not know or care if the spark actually took place or not)...

So !! (finally) Why is the Motec not triggering the CDI, and why does it appear to be at revs/boost etc?

The Motec is not showing any real errors - although it does pop up the occassional Ref/Sync error which might happen at any time and does not necessarily cut out the motor. MY tuner says its not unusual to see the odd ref/sync error here and there though..

CDI has discrete feed from 12v.

Motec has discrete feed from 12v.

We have tried swapping in another Motec M800 in to see.

We have tried swapping another ref/sync unit from another Skyline in to see.

And the only sensor 'shared' with the standard ECU is the Ref/Sync sensor so I am wondering if this would pull the current down enough to cause an issue..? And perhaps when the Motec had 17v to it, it was enough to perhaps pull up any low sensor inputs?? (or something like that)

Tonight, we are putting in an M800 with full logging to see if anything shows up, but the tuner is perplexed that it is not throwing any errors up.

Any thoughts from you guys that I can take to the workshop tonight wouldn't hurt!

The tuner has been a Motec dealer for years and has run a V8 Supercar race team a few years back so is no idiot, but has not done a lot with Skylines and so it may be something simple. And er, I just drive the car, so I am no expert either...

Your confusedly,

Matt.

[R32 TT]

Isn't it just typical... 3 or 4 nights of scratching heads and wondering what the hell is going on and then, when I think "hmm, I'll put the question up on the forums to see if anyone knows" ....and BAM! We found it...

So just for future reference:

The Motec CDI was being triggered to 'On' by the Motec ECU via one of its auxillary outputs. Our best guess is that this was inducing noise back up to the Motec ECU, or possibly drawing too much current down the trigger wire, and shutting the CDI down. In any case, we ran the trigger wire to 12volts from the ignition circuit and problem solved.. the CDI zoomed through to 9000rpm without a glitch.

....and here we were looking at sensors and readings and all the other stuff...!

Thanks to anyone who at least read the message and gave it some thought.

[NXTIME]

Nice setup there. Good to here that it was sorted out quickly. The question begs: how much power did she make?

[R32 TT]

Nice setup there. Good to here that it was sorted out quickly.  The question begs: how much power did she make?

<{POST_SNAPBACK}>

Thanks NXTIME,

Well, I didn't put the figure because I've read some mighty large figures on this forum and the dyno this is on, is known to read a bit low. So not sure if I am 'comparing properly'.

But, before I did mods I got 250hp at the rear using 1.1bar on the std turbos.

In that trim it did a 12.3 @ 110mph.

Now I have added Motec, CDI and Garrett turbos (about N1 equiv) I am getting 320hp at the rear on same dyno with 1.2bar.. we still have tuning to do so it might go up to 330-340, not sure. The cars seems much better in the torque department though.

To put the figures in perspective, a dead stock 250kW Clubsport got 240hp at the rears and a 300kW GTS got 290 on this same dyno... so it sounds like I have about 330kW at Flywheel? Not big compared to what else is on here, but a 25% improvement in what I had so... should be scraping a flat 12 or late,late 11 perhaps?

The drive on the road will be the test. I'm hoping she's pretty responsive.

[NXTIME]

250rwhp is very low for a 12.3@110mph. What was the 60'?

Sounds like that dyno is about 15-20% too low. With 330-340rwhp (on that particular dyno) the car should run well into the 11's and 120MPH. Either way, the track numbers can't lie. Good luck with it.

[R32 TT]

250rwhp is very low for a 12.3@110mph. What was the 60'?

Sounds like that dyno is about 15-20% too low. With 330-340rwhp (on that particular dyno) the car should run well into the 11's and 120MPH. Either way, the track numbers can't lie. Good luck with it.

<{POST_SNAPBACK}>

Yeah see that is what I figured.. I guess it doens't matter so long as I keep tuning and comparing on the same dyno.

My 60ft was 1.9secs on worn out street tyres.

Guess I'll have to get down again now and see what the new power figure produces!

Might take it to another dyno too where they run 'shootout mode' and see what it says there... just for interest.