FIFTH INJECTOR CONTROLLER

This is my fifth injector I design when I turbocharged my Swift Gti. It is now able to use 16 pressure/loa points as well as 8 rpm points.

 It uses a basic microcontroller and pulses the injector once per revolution of the cranks shaft. The maximum pulse length is 8 milliseconds.

The controller has three basic connection. Three wire go to the Map sensor, two go to the injector , One goes to the negative end of the coil and the other two is Power. The controller is programmable form a Lap Top.

The controller is design to work with Saturated Injectors.

 Basic stamp Oem. Programmable Interval timer.The interval timer is fed with a clock using a ne555 timer. Frequency to voltage converter, Analog to digital converter can be identified on PCB. The spark pulse is divided by two to trigger the interval timer.This is to allow the injecotrs to fire once every crank revolution as there are two spark pulse every revolution. This is accomplished by use of a flip flop. NTe 4013.

 The LM2917 is responsible for cnerting the frequency/pulses from the coil to volatage. As the rpm increases the voltage increases. On the board bottom left is an ltc1298.This is a two channel a/d coverter. Its responsibility is to convert the voaltage which is proportional to the rpm to binary value or a form the microcontroller can understant. It also read the pressure from the maqp sensor. Armed with these two values a injector value can be retrieved from a fuel map.

 The injector values are values between 1 and 255.The car generates two pulses per revolution. A flip flop (nte4013) devideds this by half to produce a pulse every revolution. A 5254 or programmable interval timer. is used to generates pulses. The pulses values come from the table just descirbed. This value is loaded into the timer. The timer is triggered by a spark pulse(one very revolution becuase of the nte4013). It start counting at the same time it output goes low. When it reaches zero it output goes high. This output is fed to a power transistor which drives the injector.The signal to the injector is first inverted before it goes to the transistor.This is done by the 74c00n a 4 inout nand gate.

The above diagram show how the adc converter is connected in general.

 The most tricky circuit was the lm2917.It required a bit of trial and error to get the values of the capacitors and resistor correct. A vlaue of 0.1 ,12k and 22uf seem to work very well.PLease stay tuned for a full parts list and a schamtic diagram

 The next design is a circuit to allow the Starlet to operate without the distributor. It will take one trigger from the ECU and generate two triggers for an MSD DIS which drives two coils using a Wasted spark technique. An MSD tachadapter will be required so that the ECU wil get an IGF signal.

The above diagram shows The clock for the programmable interval timer.Is basically a astable whose frequency is set by the resistors and capacitors. capacitor is o.1 uf and the resistors are 1k and 2.2k

Below is a diagram of the programmable interval timer.When loaded with a value it counts down to zero. Its output goes low until zero is reached. It is therefore a simple matter of sending didferent values to it to get different outputs.

The clock input is fed from the ne555 astable counter.