* Crankshaft Reference AngleThis...
* Crankshaft Reference AngleThis is the amount of advance the crank sensor is set for. This is a guess on initial start, but once the engine is running you just set the ignition MAP to a fixed advance, such as 20 degrees, and using a timing light, change the reference angle until you get 20 degrees. When this is complete the reference angle is never changed again
* Firing Order-Duh
* Engine Displacement and Injector Flow Rates
This is important for the ECU to predict injector pulse widths
The cam sensor mount was easy since the customer wanted to use a Jesel beltdrive. One nice thing about the Jesel is the cam gear is aluminum and exposed, making it easy to insert a magnet and mount the sensor. If you did not have access to the cam gear, then you would go back to using a single-point reluctor distributor to generate the cam signal. With coil-on-plug, no distributor cap would be required, but there would still be a small module installed where the normal distributor would go. Mopar Engines West is going to be fabricating special distributors for Mopars that generate both the cam and crank signals for sequential EFI conversions using a normal coils and a distributor cap.
Sequential System Timing
So we hear you asking, "What is actually going on here?" Here is a system timing description and diagram that take you through one complete engine cycle.
* The cam signal occurs sometime between the last cylinder fire (number 2 cylinder) and before the crank signal on number one cylinder. This is the beginning of the engine's cycle
* Since this is the compression stroke for number 1 cylinder, the ECU is now starting the injection for cylinder number 6, whose intake valve is just beginning to open. It knows cylinder 6, because it counted crank signals from the last cam signal
* The crank signal occurs at approximately 50 degrees BTDC
* The ECU generates the ignition timing-signal between 10 and 40 degrees BTDC depending on engine conditions (Fuel mixture for this compression stroke was injected into cylinder 1 when cylinder 6 was being fired).
The EDIST (Electronic Distributor) is really a simple box. It receives both the cam and ECU-created ignition signals; then it synchronizes on the cam signal and counts ignition signals to determine which coil to fire. We had to make our own cable between the EDIST and each coil, so we used shielded cable (RG-174) to eliminate any chance of electrical interference.
Timing Diagram For Sequential EFI And EDIST Setup
We used an MSD crank trigger for the ignition, and then we configured our own cam sensor using an MSD universal cam pickup with magnet (PN 2346). We used the MSD Pro-Billet 1,000-cfm throttle body because it came with TPS and IAC, and provided a vacuum tap for our MAP sensor. We mounted the air temp sensor in the air cleaner, and the coolant sensor in the water line going from the block to the radiator. We welded a common O2 bung in the exhaust just after the collector. Once all this was completed we plugged everything into the ECU harness. The harness is well marked with unique connectors, making it almost impossible to plug anything in the wrong place.
The F.A.S.T. ECU also controls the fuel pump and cooling fans when used with external relays. The only harness connection we did not use was for the knock sensor (ESC). The EDIST box needed a trigger signal, which was provided by the ECU. This is the wire that would normally be used to trigger the ignition. The EDIST box also needed to see the cam signal, so the cam sensor wires were connected to both the ECU and the EDIST. We made our own cable to connect the EDIST coil signals to each coil.
We loaded the F.A.S.T. software on our laptop and connected the RS-232 cable. Then we powered up the fuel pump and set the fuel pressure to 45 psi while we checked for leaks.
Before you do anything, you have to make sure the ECU and your laptop are communicating. Once the ECU is powered up, select "connect" and the laptop and the ECU are linked. as long as you are linked, anything you change with the laptop automatically updates the ECU. The ECU has a nonvolatile memory, meaning that it will remember the program even if power is removed.
Initial Software Setup
The system needs to know what kind of engine it's going to be running. We spent a few minutes setting up the basic parameters for the first start.