ofac loom
3 posts • Page 1 of 1
This might help
Scort wrote:Helpfull information!
Firstly a brief description of how and why:
Introduced in 1990. The EEC-IV module is the heart of the electronic engine control system and is based on a microprocessor-controlled electronic circuit. It compares signals from its various electronic sensors with stored engine operating parameters, varying the engines operating settings directly according to engine load and environment.
Ignition is electronic via a DIS (Distributerless Ignition System) coil and E-DIS 4 module. From signals generated by the crankshaft position sensor (CPS), the E-DIS 4 module generates a profile ignition pulse (PIP). From this PIP, the EEC-IV module calculates a Spark Advance Word (SAW) as a means of defining ignition timing (or firing point). The E-DIS 4 module uses the SAW signal to control the DIS coil. If the EEC-IV module develops a fault, a Limited Operation Strategy (LOS) comes into effect allowing the driver to continue the journey but with restricted power and economy. Under LOS conditions SAW and PIP signals are not used.
The EEC-IV module is provided with a memory which is used for control matching, diagnosis and self testing.
With the engine running the E-DIS 4 module receives the SAW signal in a 'window' extending from 10 degrees ATDC to 170 degrees BTDC. The signal is therefore outside the ignition advance and retard range (10 degrees ATDC to 57 degrees BTDC) and cannot be influenced by HT disturbances.
When the engine is started or running at low speed, or operating in LOS mode, ignition is triggered by the E-DIS 4 module at 10 degrees BTDC and is not controlled by the SAW.
The DIS ignition coil consists of two coil windings converting the voltage signal from the E-DIS 4 module into HT and supplying this HT to the spark plugs in the correct firing order.
The crankshaft position sensor (CPS) is an inductive proximity switch reacting to the 36 webs cast onto the rear of the flywheel. One web is missing causing a gap and is used to denote 90 degrees BTDC on number one cylinder in the firing order. The signal generated by the CPS is used by the E-DIS 4 module to determine actual ignition timing. On engines with an open loop principle (as opposed to those with a closed loop incorporating a catalyst and HEGO sensor), the CO adjustment, a 5 kohm potentiometer supplies a substitute CO value to the EEC-IV module in place of the HEGO sensor. (Heated Exhaust Gas Oxygen Sensor).
Moving swiftly on, here is a wiring diagram of the FRST engine loom:
This covers the main parts of the EEC-IV, it does not include the EDIS-4, however that is fairly self explanitory.
A photograph of an OFAC engine loom:
Key:
1: ECU
2: MAP sensor
3: Diagnostics connector & CO Idle adjust connector
4: Current return
5: EDIS-4 connector
6: Crank Position Sensor
7: Connector to engine loom (injectors etc)
8: Speed Sensor
9: DIS Coil
10: Oil pressure switch
11: Amal Valve
12: Current return
13: Idle Speed Control Valve
14: CO Adjust POT
15: Connector to car loom
The connector to car loom is configured in the following way:
Looking onto the engine loom connector
Pin 1: Ignition Live
Pin 2: Pin 22 (ECU) to the Fuel Pump Relay
Pin 3: Fed From DIS coil pack to the Rev counter
Pin 4: Pin 20 (ECU) Current return
Pin 5: Pins 57 & 37 (ECU) to the Fuel injection Relay
Pin 6: Oil Pressure
Pin 7: B+ (Constant Live)
Some more wiring colour information: ECU Pinout details,
1, Red -- +ve
3, Brown/Yellow – octane / idle adjust
4, Brown/White – speed sensor
7, Brown/Green – engine temperature sender
16, Brown – current return & 40
17, Brown/Green – diagnostics connector
20, Brown – current return
21, Brown/Yellow – idle speed valve
22, Brown – fuel pump relay
23, Brown/Red – octane / idle adjust
24, Brown/Blue – octane / idle adjust
25, Brown/Yellow – air temp sensor
26, Brown/Black – throttle sensor & co adjust pot & map sensor
27, Brown – CO adjust potentiometer
28, Blue/Yellow – Pin 2 on edis (disconnected)
33, Brown/Green – Boost control valve
36, Blue/Red – Pin 3 on edis
37, Black – idle speed valve & injectors & Speed sensor & Boost control (tbc) & 57
40, Brown – current return & 16
45, Brown/Yellow – map sensor
46, Brown – map sensor & engine temp & air temp & throttle & CO adjust
47, Brown/Green – throttle sensor
48, Blue/Green – diagnostic connector
56, Blue/Yellow – Pin 1 on edis
57, Black – idle speed valve & injectors & Speed sensor & Boost control (tbc) & 37
58, Brown – Injectors
59, Brown – Injectors
60, Brown – current return
Some of the above information is saved from a very oily notepad, so there is likely to be some arse ups, if there are tell me and I will change them.
Hope they are of some help to a few peeps!
Steve
- j7aoc
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Car: 1991 Ford Fiesta RS Turbo
3 posts • Page 1 of 1
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