Ford Sierra Cosworth 2wd
- 4 cylinder inline engine, with fire order 1,3,4,2
- displacement: 2L
Originally with Weber-Marelli engine management.
Trigger
Engine RPM/TDC Sensor - VR type
The crankshaft pulley has 4 identical teeth spaced at precisely 90°. The sensor sends a signal to the module whenever a tooth passes a the sensor. From this signal the module determines engine speed (RPM) and the TDC position of each piston (crankshaft position).
Note that pistons are 180 crankdegrees apart, so half of the pulses do NOT belong to pistons. This means this sensor requires camsync to operate. Not as convenient as a normal Bosch 60-2 or Rover K4-type pattern.
The distributor phase sensor (camsync) - also VR
The distributor is driven by the auxiliary shaft as on the standard ohc engine.
A phase sensor, located opposite a cam having two teeth separated at 90° (camdegrees) to each other, is fitted inside the distributor. At the passing of a tooth the sensor delivers a signal to the ECU. This signal is similar to the signal supplied by an RPM/TDC sensor fitted at the crankshaft pulley.
The signal from the distributor and the RPM/TDC sensor together enable module to identify the phase of each cylinder.
Note: the polarity of both sensors must be investigated. This is simple, but shouldn't be forgotten. And inverted if necessary, considering that the VR input HW senses the 0-crossing falling edge. (internally rising edge is configured when VR is used, since that is the output of the VR chip; but the VR input is always falling edge).
Unfortunately this trigger arrangement is not currently supported by firmware.
- with only 1 campulse, it is supported. Short-dwell ignition transformer (or CDI) is required for high RPM
- Is the crank-pulley special in some way ? Is there a chance it can be swapped for a
- multitooth pulley? (available in junkyard, as a long-lasting part that lives well beyond the engine)
- 2 pulses, 50..90 crankdegrees TDC would also work (grindoff ?) with 1-pulse camsync, but a multitooth is unbeatable.
- how many engines are planned of this install ? It is possible to add firmware support, but it's not without costs
- I plan to build 3 engine with vems at first, but this engine management system is used by most of cosworth (Sierra Cosworth 3 door, Sierra Cosworth 2wd saloon, Sierra Cosworth 4wd saloon, and big-turbo Escort Cosworth)
Other sensors - seems very smooth
The Throttle Position Sensor (TPS)
This unit is fitted to the throttle shaft and senses the throttle position. at idle speed voltage is 5.0-4.5 volts and at full throttle the voltage drops to 0.5 volt.
The Manifold Absolute Pressure (MAP) Sensor
Depending on the manifold pressure, the sensor regulates between 0.25 to 4.75 volts.
- If manifold pressure exceeds 0.9 bar, the sensor signals the ECU to cut-off fuel
- the threshold is just configured in the ECU, no plus wire.
The Air Charge Temperature (ACT, MAT) Sensor
This sensor is of the NTC resistor type, its resistance decreases as temperatures increase.
Engine Coolant Temperature (ECT, CLT) Sensor
The ECT is also of NTC resistor type and its operating range is identical to that of the ACT.
Actuators:
Ignition module
The ECU sends a Spark-out signal to the ignition module (well, twin-transformer; right ?;?what it means?; it's a simple distributor+coil setup, not wasted spark or another) to trigger an H.T. pulse by switching the coil primary circuit off.
- sounds like ECU needs to be ordered power (IGBT) output and dwell is controlled by ECU
- dwell is totally governed by the module and cannot be adjusted, unfortunatelly no more data about ignition module
The Fuel Injectors
The ECU provides accurate control of the solenoid operated fuel injectors to discharge fuel.
The Idle Speed Control (ISC) Valve
This unit is regulates the engine demand for air depending on the engine temperature, engine load, or swithed on accessories.
The valve, whichis controlled by a variable current from the ECU, adjust the air flow into the engine.
The valve is pwm modulated.
The Boost Pressure Control Valve
This solenoid valve is directly connected to the high pressure side of the turbocharger by a hose. Depending upon whether the valve is open or closed it will either "vent-off" a portion of the boost to the inlet side of the compressor (valve open) or direct it to the wastegate actuator (valve closed)
I need some advice about the hw configuration of vems.
- Can I use this VR sensors?
- yes
- Is this Vr sensor configuration suitable for VEMS?
- not in this form without firmware modifications
- What type of ignition driver configuration do I need?
- sounsd like IGBT, but more info on the "ignition module" is needed to tell for sure. Since only 4 cyl, 4+4 can be a good bet to suit either.
- Do I need power flyback?
- recommended.
Thx any help!