Cosworth P8 ECU Reset

The engine management system on the Large Turbo Escort has what is known as ‘adaptive learning’. This in simple terms means that the engine management system will make changes to the fuelling of the engine, based on the information it receives from many engine sensors.

Earlier models of the Cosworth had an adjustment screw to allow fine-tuning of the fuel mixture. The Escort Cosworth does not have this facility; the engine management system will make these adjustments itself. Over a period, the management system ‘learns’ where the fuelling isn’t correct, and applies a richening or leaning off adjustment to the fuelling at the relevant points in the fuel map. Unfortunately, many additional factors can affect the fuel mixture readings, and this can sometimes cause the management system to make an incorrect adjustment. If the adjustments made by the management system are too severe, the fuel mixture reading will fall outside of the operating range of the Lambda sensor.

If this situation occurs, the management system will be unable to readjust the mixture correctly. In this case, it will be necessary to re set the engine management system memory, and allow it to ‘re- learn’ the running strategies.

To re set the memory, you must carefully follow the following procedure (with the engine stopped and at normal operating temperature):

1) Locate the memory re set plug inside the engine compartment and remove the red cover (if fitted). On right hand drive vehicles this can be found between the battery and front suspension top mounting. There are three diagnostic plugs here, (see photo), the circular plug is the memory-reset plug. (On some models, this shape of plug is used to alter the ignition timing for different octane fuel).

2)You can use our adaptive reset plug to connect these 3 wires together. DO NOT CONNECT TO THE PLUG YET.

3) You will need help to complete this part of the operation. Turn on the ignition, as if to start the engine. (Operate any immobilisation systems etc.) DO NOT START THE ENGINE. You will hear the idle speed control valve click slowly (about once per second). As soon as the ignition is switched on, (but not before), connect your three pieces of wire to the plug sockets to inter-connect all three terminals. This must be done quickly, after the ignition is turned on, but before the fuel pump stops priming the engine. After about seven seconds, the idle stabiliser will stop clicking. After a further twenty or thirty seconds, the idle stabiliser will click extremely quickly, then return to clicking once per second. When this happens it signifies that the management system Kept Alive Memory is erased. Turn off the ignition, and remove your wires from the sockets. Re fit the red plug cover and return the diagnostic plugs to their original position. Do not worry if this doesn’t happen first time, you may find it necessary to carry out the erasure procedure at least twice until the operation completes as described.

4) The management system now has to re learn its idle and slow running strategies. Allow the engine to idle for three minutes, then increase the speed to 1200 RPM and hold for two further minutes.

The engine management system should complete its learning strategy after approximately 5 miles of varied driving.

This is firmawre dependant, and will not work with chips using ALS/LC as they use the same pin configurations as the reset, 13-14-11. In these cases you would need to swap the eprom for a Std firmwear version to do the reset, then swap back and run.