Could be caused by low fuel pressure. Check fuel pressure regulator collar. If the collar is coloured blue, replace with a revised pressure regulator with a white collar. The revised regulator maintains the holding pressure for longer allowing improved cold starting.
Hesitation or a flat spot during cold or hot running. Often caused by oil contamination of CAS. Extra care is required during oil changes due to the proximity of the CAS to the oil filter.
Also, flywheel ring can be incorrectly fitted in reconditioned engine, resulting in fluctuating and irregular CAS signal. Engines with this fault will stop and are sometimes difficult to start.
The hydraulic lifters can reduce in clearance and cause a breathing problem on the Ford 2.0 DOHC engine. This results in a severe reduction in power (usually when hot). The hydraulic lifters are supplied in two sizes. It is preferable to use the larger size as a replacement.
Often caused by incorrect (usually low) base idle speed setting. Adjust idle speed or throttle as described under Adjustments.
Could be caused by faulty or open circuit CO pot. Fault often shows up during 'scope test.
The ECM and EDIS module are usually reliable and do not often fail. The Stepper Motor is usually very reliable and does not often fail. The ISCV is more reliable in later models. Hall Effect sensor used in most vehicles is usually reliable. However, the type used in the V6 engine may be less reliable and the trigger vane may work loose and disintegrate. Ford Fiesta fuel pumps are prone to failure and it is necessary to remove the fuel tank to change the pump.
An unregulated catalytic converter was an optional extra for the 8v DOHC engine. This option could be fitted when the vehicle was new or shortly afterwards. Once the vehicle passed to the second or subsequent owners, the fact that a catalyser was fitted may be unknown. Since the petrol filler cap is regular size, the petrol tank could be inadvertently filled with leaded petrol, resulting in a contaminated cat and a blocked exhaust.
Sensor terminal pins partially disengaging or making poor contact. This fault can afflict a number of the sensors and, unless it affects the CAS, is rarely crippling. The ECM will enter LOS for most faults and run almost normally. Fault codes will be logged for most conditions.
When any engine sensor is renewed (Ford o/e) it will have gold plated terminals. Since these terminals will not make a good contact with the tin plated terminals in the wiring loom multi-plug, a fly lead and multi-plug conversion containing gold terminals is also available from Ford. The vehicle loom multi-plug must be cut away and the new fly lead and multi-plug carefully soldered into the original position. Beware of sensors with incorrectly soldered connections and poor connections caused by tin plated multi-plug terminals connected to gold sensor terminals.
The DIS coil pack on CVH DIS models is prone to failure, resulting in stalling etc. Use a 'scope to check the kV output.
A faulty fusebox in early Zetec engines can lead to complete electrical failure or a number of components supplied from a particular fuse.
Often caused by an incorrect (usually low) base idle speed setting. Reset as necessary (where possible). If difficulty occurs in adjusting idle speed, check for sludge in throttle body or maladjusted throttle valve.
Corrosion in the multi-plug connection or a faulty TPS. This fault causes hesitation and flat spots on acceleration. Sometimes, when a new TPS is soldered into position, incorrect connections are made and this leads to much worse acceleration than before the sensor was renewed.
Many faults are caused by defects in the secondary HT system. Faulty or incorrect components (i.e. an unsuppressed wire HT lead) could lead to RFI that could easily disrupt ECM operation. Mondeo N° 4 HT lead is commonly found to be faulty. Check with oscilloscope and/or ohmmeter.
Lower battery voltage and greater current draw can create an interference condition that causes the EDIS module to trigger too early. The symptom is very similar to the type of slow cranking experienced with 'advanced ignition timing'. The result is a poor or non-starting engine. A revised EDIS module was fitted in production in 1992 and is available as a service replacement.
Check at alternator, could be bad earth connection or bad connection on the starter solenoid supply terminal.
A faulty CO pot (where fitted) can cause idle problems. Check for a smooth signal output. A 'scope is ideal for displaying a break in the signal from this sensor.
If the Secondary Air system becomes faulty so that air is injected when the engine is hot, this will lead to a very weak mixture in the exhaust system. A weak exhaust mixture could lead to backfiring and damage to the exhaust system.
There are many variations of the EEC IV ECM and it is possible to fit the incorrect ECM with resultant poor running.
A common fault on most Ford engines is a worn VSS or a VSS wiring fault. This can affect idle instability and injection cut-off during deceleration.
On a CVH engine check for camshaft belt breakage (may be caused by seized water pump). Check for poor ECM earth at battery connection. Re-solder poor connections. Disconnect MAP sensor (where fitted) multi-plug. Attempt to start engine. If the engine starts the MAP sensor is suspect. Check the 5.0 volt reference voltage from the ECM to sensors such as the TPS etc. If the reference voltage is low, check the main relay. Check for fouled sparkplugs or a blocked exhaust system (a defective cat could cause an exhaust blockage).
Vacuum leak at oil filler cap or oil dipstick.
Sticking, faulty or dirty ISCV, usually caused by fumes from the breather system. When the ISCV is dirty, it is unable to respond quickly to the ECM pulses and thus moves out of synchronization. This causes a fluctuating idle speed. Cleaning the ISCV with carburettor cleaner will usually affect a temporary cure. Ford suggest drilling a 3.0mm hole in the centre of the throttle plate and this is said to make a more permanent cure. Once the hole is drilled, the basic throttle plate position will need to be checked and reset. Adjust TPS.
Engine breather fault (2.0 SOHC engines). A modified breather system is available, see Ford bulletin N° 10, dated 8th Feb 1988. The modified breather can be identified by checking for a hose connecting the air intake hose to the oil filler cap. Once the modified breather is fitted, the basic throttle plate position will need to be checked and reset. Adjust TPS.
Engine breather fault (2.0 SOHC engines). A modified breather system is available, see Ford bulletin N° 10, dated 8th Feb 1988. The modified breather can be identified by checking for a hose connecting the air intake hose to the oil filler cap. Once the modified breather is fitted, the basic throttle plate position will need to be checked and reset. Adjust TPS.
A faulty HES could cause erratic misfire and possible rough idle. Make the HES and TFI measurements. The HES is usually reliable when fitted to models other than the V6 2.9 engine. In this engine the HES has been known to falls to pieces and the trigger vane may becomes loose.
Activation of the Inertia switch can also be caused by a heavy thump in the passage compartment in addition to an impact or sudden deceleration. An example may be heavy stowing of luggage or other bulky objects.
Non-running or lack of power in 2.8 engines. The camshaft fibre toothed drive gear is prone to stripping in high mileage vehicles. Damage to the distributor signal wire when it becomes trapped between the cylinder head and the rocker cover.
Blown inlet manifold gasket (usually on one of the LHS bank cylinders).
Possibly due to a faulty VSS: During normal vehicle operation the 2.9 Transit engine speed is limited to 6100 rpm and the road speed governed to 86 mph. If the VSS circuit develops a fault, EEC IV will enter default mode and restrict the engine speed to 3500 rpm by inhibiting fuel injector operation.
From 1995 the Probe vehicles were equipped with an immobiliser that has created some problems. The immobiliser is wired into the ignition output signal from the distributor and may disrupt the output signal despite the immobiliser being disarmed. A kit is available from Ford to increase the amplifier output and this usually solves the problem. It is also possible to rewire the ignition wiring and thus by-pass the immobiliser.
Cut the two wires leading to pins 10 and 13 at a position close to the immobiliser ECM. Join the two wires together that are not connected to the immobiliser. These wires lead to the distributor and to the ECM and the result is an uninterrupted signal from distributor to ECM. Join the two wires together that are connected to the immobiliser (pins 10 and 13) and connect to ground.
Cut the two wires leading to pins 10 and 13 at a position close to the immobiliser ECM. Join the two wires together that are not connected to the immobiliser. These wires lead to the distributor and to the ECM and the result is an uninterrupted signal from distributor to ECM.
Join the two wires together that are connected to the immobiliser (pins 10 and 13) and connect to ground.
Cut the two wires leading to pins 10 and 13 at a position close to the immobiliser ECM.
Join the two wires together that are not connected to the immobiliser. These wires lead to the distributor and to the ECM and the result is an uninterrupted signal from distributor to ECM.
Join the two wires together that are connected to the immobiliser (pins 10 and 13) and connect to ground.
