Posted 16 June 2018 - 09:46 AM
Quite some time ago SC were sending out looms which had the polarity of the crankshaft sensor inverted. I know two people who had this. One, the engine would start and then just die straight away, the other it just wouldn’t start. Now that is not to say they haven’t fixed this, I’d like to think they have as it’s now been easily 10 years since.
You need to really start with the basics when starting an unknown set up. ( forgetting for a minute that it’s already been dyno’d).
One of the most important things to check is that the ECU is receiving the crank position signal. Firstly, it is wise to disconnect the injectors so you don’t flood the engine unnecessarily. You should first check that the rpm gauge on the tuning application software reads maybe 150 to 200rpm when the engine is being turned over on the starter. If you don’t get that, you need to work out why. You could maybe double check that using the timing light. No crank signal, no spark or fuel.
Problems associated with crank signal are few. Mainly sensor wiring polarity and Air gap.
With polarity, it’s not just as simple as looking at it and saying that it’s right or not, that is unless you know already which wire on the sensor is positive and know which wire on the loom connector goes directly to the primary trigger input on the ECU. Rather than messing with the loom to try and invert the polarity, it might be easier to make up a small adapter loom with a male and female connector and invert the polarity that way (technically called a crossover cable).
Sensor gap needs to be adjusted so that it is no more than 1mm. The closer to the target the better so long as it does not touch.
Once you have the crank signal reading RPM on the tuning application software, you then need to make sure the missing tooth is where it needs to be in relation to top dead centre of the engine. In the ECU will be a value ‘trigger before top dead centre’ or something very similar. Values are usually between 60 and 90 degrees. This means the missing tooth will pass the sensor before top dead centre. With the engine at top dead centre count the number of teeth counter clockwise from the missing tooth until you reach the tooth the sensor is pointing directly at. Multiply that by 10, this is an estimated ‘trigger before TDC’ value. If it’s more than 90 or less than 60, I’d suggest you should re position the tooth wheel to bring it into the above range. Once you have the estimated value and entered this setting in ‘trigger before TDC’ you then need to calibrate it using a timing light. By changing the cranking ignition timing degrees to zero, (again making sure the injectors are still disconnected) turn the engine over on the starter and check the timing marks on the engine line up at zero degrees (TDC). If they don’t, alter the ‘trigger before TDC’ value in the ECU settings until it does. Then change the cranking ignition timing back to what it was originally, usually somewhere around 5 to 10 degrees in most cases.
You then need to calibrate the throttle position sensor. I’m not sure how this is done on the SC system (I lost interest in the system a long time ago) but you should be able to find that information in the user guide.
If you are using a MAP sensor, you need to make sure the ECU settings are appropriately set for it and it is also calibrated. You will be able to find the current barometric pressure online, and calibrate the MAP sensor to read this value with the engine not running.
Other thing to consider is the spark order on the coil pack. The wasted spark coil pack consists of two coils. Coil one will supply spark to cylinder 1 & 4 while coil 2 supply’s spark to cylinder 2 & 3.
Then of course make sure fuel pressure is around 3 bar, and fuel lines are correctly connected for the fuel system you are using.
Unfortunately I’m not sure you can remove the injectors from the throttle body with the fuel rail still attached and turn the engine over to see whether they are firing or not, as the injectors are held into the fuel rail when it’s in position on the throttle body, they might be pushed out of the fuel rail by fuel pressure alone, and that is not something you want to experience !