Ross Nicol
GT40s Supporter
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
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