Questions and Answers
Ford Duraspark Ignition System
Q. Hi, I have a problem and probably you're the only people who may be able to give me a clue. I live in the UK and have a 1984 Mercury Cougar 5.0 liter with a Duraspark ignition. It does not run! The problem is that my model apparently was only produced for a short time so there is very little info on how it works.
My main question is that there should be a sender somewhere to tell the ignition electronics when to spark as there is nothing inside the distributor apart from the cap. It has to be somewhere off the crank I assume but I have not found it yet. Any Ideas? I may well have a wiring problem but I need to know where all the bits are. Hope you can help. My wife runs an 1984 as well but with the 3.8 V-6 and I'm jealous.
Living in hope...
NigelA. The Dura Spark III system is used on vehicles equipped with Electronic Engine Control (EEC) III. The system consists of a primary side consisting of the battery, ignition switch, primary circuit, EEC system input and ignition module, and a secondary side consisting of distributor cap, rotor, spark plug wires and spark plugs. When the ignition switch is in the On position, the primary circuit and the ignition coil are energized.
The EEC system provides a signal which tells the ignition module to turn off the coil primary circuit. The off and on times of the primary circuit are controlled by the EEC computer. When the circuit is turned Off, the magnetic field built up in the ignition coil collapses, inducing a high voltage into the coil secondary windings. This high voltage is then delivered to the spark plugs by the secondary ignition wires.
The control module has no purple wire (Dura Spark II) and can be distinguished by the brown sealing block or grommet. Ignition timing is determined by the crankshaft position sensor (CP) and several other EEC related sensors which feed information to the Electronic Control Assembly (EEC processor) through the 32 pin connector.
The various input sensors are (depending on if the vehicle is carbureted or fuel injected), the exhaust gas oxygen (EGO), engine coolant temperature (ECT), EGR valve position (EVP), throttle position (TP), barometric manifold absolute pressure (BMAP), and air charge temperature (ACT) sensors.
Typical Dura Spark III ignition systemThe crankshaft vibration damper is fitted with a four-lobe "pulse ring" which provides the system with an accurate indication of when the pistons reach 10° BTDC. This indication is called the reference timing.
The pulse ring is a powdered metal ring positioned on the crankshaft vibration damper during manufacture. It has four equally spaced lobes which represent crankshaft position when the pistons reach 10° BTDC.
During operation, the lobes on the pulse ring pass by the tip of the CP sensor. The pulse ring interrupts the magnetic field at the tip of the sensor. When the field is interrupted, an output signal is generated and sent to the ECA. As the crankshaft turns, the ECA evaluates the electrical impulses to determine the exact position of the crankshaft at any given time. By the frequency of the impulses, the ECA can determine the engine speed. With these two factors, the ECA will determine the appropriate ignition timing advance required for best engine operation.
Crankshaft position sensor (EEC-III)Personally, I have found that nine times out of ten, it's the control unit that goes bad.
Additional Information provided courtesy of ALLDATA
