Motec Tips

[Ross Nicol]

I have just fitted my old motor back in the 40 and had the old learning curve again with the Motec so thought I'd pass on some tips.
There are quite a few options when it comes to triggering a Motec unit so here is my setup.
M48 ECU
Ref and Sync triggers built into distributor
Runs sequential injection
single coil
Now since I am running sequential injection, rule one is you have to wire the injectors to match the firing order. Easily done but a real bugger when you fit a motor with a different firing order. Fixed by using short extension leads.
Fit the plug leads to the dizzy cap following the firing order but you don't time the engine by rotating the dizzy. You install the dizzy and set the crank to 25°BTDC and turn the dizzy till the centre of the rotor button points directly at #1 post in the cap. Now lock down the dizzy because all timing from here is done electronically.
Now to explain how the 2 triggers work.For every crank rotation there are four Ref trigger pulses 90° apart so you can also say there is a Ref signal for every TDC. Together with the Sync pulses, very accurate operation of injectors and ignition is achieved.Now those among you who are still with me will ask how does the system know which 90° signal is #1 and for sequential operation this is vital info. My engine started and ran but believe it or not it thought #5 was #1 so it didn't run well.
The trick is to establish a crank index position and to do this you load an offset number into the computer and check with a timing light to make sure the computer advance timing matches the physical crank timing. My son James and I set mine up tonight and now #1 really is injecting at the correct time the motor runs like a dream. Sorry if I have confused but thought I'd pass the info on. Now I feel comfortable I can race the car at the weekend and really give it some stick.
Ross

 

[Keith]

I must have missed something Ross. Why are you back to the "old" motor?

 

[Paul Thompson 'Hooligan']

Nicely explained Ross, especially the bit about locking locking down the dizzy and not chasing your tail rotating it back and forth....

We reverted to an 'older' motor on Roy's GTD after failure of the alloy Clevor and when we tried to start it, lots of bangs and wooshing of flames as the firing order was different also. As Roy's has individual coils per cylinder, it was not possible to get the order right by shifting leads on a dizzy cap, so a re-wire was required.

Another tip though, IF you do need to change the firing order (diff cam), the easiest way without injector extension leads, is to release the pins from the loom connector to ECU, noting their colors (inj ccts are all 'striped') and then 'pop them back in', in the correct firing order....

It worked with the ignition amplifiers too, to correct the coil firing order too - happy days.epper:

 

[Leonard]

Ross,

Well done. Works pretty much the same way with my Accel GEN 7 system on my Mach 1.

Leonard

 

[Ross Nicol]

Keith - I ran low on oil (read Ross didn't put enough in) at the last race meeting at Phillip Island and lasted only 3 laps before the bearings got consumed.I did post but I'm not sure now where it is, check the racing section.
Paul- Yes I see the pin changes in the large connector would work but I've not had a good experience with that one.Early on I tried removing pins but before I realized you have to remove the white plastic piece in the front first, I wrecked a couple of pin locks.I bought a new connector block but didn't fit it thinking all was working why change it, until the day we went to tune the new motor.I was in the drivers seat tune man beside me with the lap top sitting on the floor.Couldn't understand why he was constantly getting sync errors and this frustrated us all through the day.Anyway I get back to the workshop to find the sync terminal making intermittent connection all traced back to me damaging the block.I immediately changed the block and have not had a problem since.I can now change those pins with confidence but I prefer to leave them alone.Could be the tool I use is a ground down pop rivet.Are there proper pin removal tools around? I would suspect there would be.My southern kiwi heritage (like Jac Mac says) we had to make a lot of our own tools, a well known phenomenon Kiwi ingenuity.Oh no! now here come the sheep jokes.

Ross

 

[Mick]

Ross can you explain what the off set number is.

mick

 

[Ross Nicol]

Yes I'll try Mick.By the way the significance of my comment in the last post about the tuning man with the lap top was, he was not only sitting on the floor of the passenger side but his backside was moving the wiring to the ECU and he was unaware he was pulling on the sync wire.Hence the intermittent connection.

Right Mick - The offset number is called the 'CRIP' by Motec and it stands for 'Crank Index Position'.Basically in order for the ECU to know where Top Dead Centre (on compression #1 cylinder) you need to specify the number of degrees of crank rotation between the Trigger sensor and TDC comression #1.Now this is easy if you have the Ref sensor on the front of the motor as you can just rotate the crank from one point to the other and read off the angle.It's not so easy with the sensors built into the distributor as in my case but it all works out eventually.
Hope that clears it up for you.
Ross