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Ford Zetec - Induction

The Zetec engine was designed to use fuel injection with the Ford plenum chamber arrangement. This provides a fully closed loop system with exhaust gas recirculation that allows the engine to meet stringent emissions levels whilst providing a reasonable amount of power. The main disadvantages of this system are that the plenum chamber sits quite high above the top of the cylinder head and installation will require the use of the ESC IV engine management module which requires other systems to be present in the vehicle for correct operation.

By utilising aftermarket inlet manifolds and engine management units, it is possible to fit twin carburettors or throttle body injection systems to the engine and replace the Ford plenum chamber arrangement. The main advantages to this are that the induction system doesn't sit higher than the engine, allowing fitment under the bonnet of many kit cars and that the engine management unit is purely designed for managing the engine and doesn't require other systems to be present to operate. A side effect of this is that due to better inlet air flow the power output of the engine is generally improved - on the standard 2.0 litre engine, this typically provides around 33 more Bhp.

If you are pre-SVA and your engine was manufactured on or after 1st August 1995 the only realistic was of passing will be to fit a closed loop injection system and a catalytic converter. Click here to find the age of your engine from its number.

Ignition and Injection

The Zetec doesn't use the traditional distributor and coil arrangement as found in older engines such as the Pinto. Instead it uses ignition and injection mapping provided by an engine management unit and various sensors on the engine. If aftermarket carburettor systems are installed, then injection mapping isn't required. Engine management units with ignition only mapping typically cost around £200 less than the ignition and injection equivalent.

In order to provide correct ignition and/or injection, the engine management unit needs to know whereabouts the crank is on its cycle. This is performed using a crank position sensor. This is a magnetic sensor which monitors a series of evenly spaced holes on the back of the flywheel. In order to calculate the flywheels position two of the holes are merged together to create an oval. On the Zetec, these correspond to when the piston in cylinder 4 is at Top Dead Centre. The signals gained from this information only tell the engine management unit the position of the pistons, not whether they are on the induction or exhaust phase.

Most aftermarket engine management units only make use of this information for ignition and injection. They fire the coil pack for each cylinder at the appropriate time. If the piston is on the exhaust phase, this spark isn't necessary. This system is called "wasted spark" ignition as one of the sparks is wasted. If injection is also being controlled, a disadvantage of this is that the injector is also fired on the exhaust stroke, thus spraying the back of the valve with petrol. This enters the cylinder and is burnt on the next induction phase.

In order to calculate what phase the pistons are on, an additional sensor is required. This monitors the position of the cam shafts. The Zetec features such a sensor, however only high end aftermarket engine management units make use of the information gained to provide fully sequential ignition and injection.

To provide full three dimensional mapping a throttle potentiometer is connected to the throttle butterfly spindle. By using the information gathered from this, a three dimensional map can be created to provide optimal ignition and/or injection based on the engine speed and the throttle position. This enables the power to be delivered smoother and helps iron out possible flat spots within the rev range by modifying the timings to compensate. It also provides for greater fuel economy.

Other sensors can be used to modify the ignition and/or injection map whilst the engine is running such as inlet air temperature, water temperature and Lambda sensors.

If you are going to use a water temperature sensor, you will also require and adaptor to mount the sensor for the water temperature gauge in the top of the thermostat housing. The part required is a 3/8" NPT male to 1/8" NPT female adaptor. Europa Specialist Spares, amongst others, sell these. The Europa part code is TE24.

Inlet Choices - Twin Carburettors

By utilising aftermarket equipment it is possible to fit twin choke 40mm or 45mm Weber DCOE or Dellorto DHLA carburettors to the Zetec.

It is possible to purchase complete kits and these typically cost slightly less than buying the components separately. If you can, I would recommend purchasing the items and building your own system. That way, you learn a lot more about the way everything works and get the appropriate parts for the job. You will require the following components:

  • 1 x Inlet manifold
  • 2 x Twin choke carburettors, appropriately jetted with linkages
  • 1 x Ignition only engine management unit
  • 1 x Throttle potentiometer for carburettors compatible with selected engine management unit
  • Optional air temperature sensor and/or water temperature sensor
  • 1 x Electronic fuel pump - Facet Red Top is recommended
  • 1 x Pre-pump fuel filter
  • 1 x Post-pump fuel filter
  • 1 x Fuel pressure regulator

The fitment process is as follows:

  • Fit throttle potentiometer to carburettors
  • Fit the carburettors to the manifold with appropriate linkages
  • Fit the manifold to the engine using the Ford inlet manifold gasket
  • Connect the fuel tank to the pre-pump filter, then to the fuel pump
  • Connect the fuel pump to the copper fuel pipe going to the front of the car
  • Connect the front of the copper fuel pipe to the post-pump filter then to the pressure regulator
  • Connect the pressure regulator to the carburettors
  • Wire in the engine management unit to the standard crank position sensor, the coil pack and throttle potentiometer
  • Connect optional water and/or air temperature sensors to engine management unit
  • Install a suitable map on the engine management unit
  • Start the engine then get it mapped correctly at a rolling road

A system based on the above equipment provides around 33 Bhp more than the standard 2.0 litre Zetec at the expense of fuel economy and exhaust emissions.

Inlet Choices - Throttle Body Injection

By utilising aftermarket equipment it is possible to fit twin choke 40mm, 45mm or 48mm Weber DCOE style throttle bodies to the Zetec.

If you plan on fitting an injection system, you will require an injection fuel tank fitted with swirl pot and return feed and two fuel lines from the fuel tank to the engine bay.

Again, it is possible to purchase complete kits, this time though, they cost a similar amount to doing it yourself. If you can, I would recommend purchasing the items and building your own system. That way, you learn a lot more about the way everything works and get the appropriate parts for the job. You will require the following components:

  • 1 x Inlet manifold
  • 2 x Twin choke throttle bodies with linkages and fuel rail (Jenvey are highly recommended)
  • 1 x Ignition and injection engine management unit
  • 1 x Throttle potentiometer for throttle bodies compatible with selected engine management unit
  • Optional air temperature sensor and/or water temperature sensor
  • 4 x Fuel injectors (Ones from 1989-1994 Vauxhall Cavalier SRi recommended)
  • 1 x Electronic injection fuel pump (Bosch pump from 1989-1994 Vauxhall Cavalier SRi recommended)
  • 1 x Pre-pump injection fuel filter
  • 1 x Post-pump injection fuel filter
  • 1 x 3.5bar fuel pressure regulator (Again from 1989-1994 Cavalier SRi)
  • 4 x High pressure copper fuel hose connectors
  • Optional lambda sensor and catalytic converter

The fitment process is as follows:

  • Fit high pressure copper fuel hose connectors to copper fuel pipes
  • Fit throttle potentiometer to throttle bodies
  • Fit the throttle bodies to the manifold with appropriate linkages
  • Fit the fuel rail to the throttle bodies
  • Fit the manifold to the engine using the Ford inlet manifold gasket
  • Connect the fuel tank to the pre-pump filter, then to the fuel pump
  • Connect the fuel pump to the post-pump filter
  • Connect the post-pump filter to the copper fuel pipe going to the front of the car
  • Connect the front of the copper fuel pipe to the fuel rail
  • Connect the end of the fuel rail to the fuel pressure regulator
  • Connect the pressure regulator output to the return copper fuel pipe going to the rear of the car
  • Connect the return copper fuel pipe to the return feed on the fuel tank
  • Wire in the engine management unit to the standard crank position sensor, the coil pack, throttle potentiometer and the injectors
  • Connect optional lambda, water and/or air temperature sensors to engine management unit
  • Install a suitable map on the engine management unit
  • Start the engine then get it mapped correctly at a rolling road

A system based on the above equipment provides around 33 Bhp more than the standard 2.0 litre Zetec whilst maintaining fuel economy and low emissions.

Engine Management Units

There are many engine management units available; however the two main user programmable ones in use on kit cars with the Zetec engine are the Emerald and the Omex. They are each available in two versions, an ignition only model for use with carburettors and an ignition and injection model for use with throttle body injection. Typical prices are:

Manufacturer Ignition Only Ignition & Injection
Omex £350 + VAT £550 + VAT
Emerald £400 + VAT £600 + VAT

Omex

The Omex is slightly cheaper than the Emerald, and this is reflected by a few less features, most notably no support to manage a closed loop emissions system using a lambda sensor. This is only required if your car is pre-SVA and the engine was manufactured on or after 1st August 1995. The software provided with the system is intuitive and very easy to operate.

Omex are a small company, however their customer service is second to none and they are always willing to help with any problems. If you don't need a closed loop system, I would recommend the Omex engine management unit.

Emerald

The Emerald system provides all that the Omex does as well as the ability to operate a closed loop emissions system using a lambda sensor. If your engine was manufactured on or after 1st August 1995 and your car is pre-SVA you will require this feature. The software is similar in operation to that provided by the Omex.

Despite several e-mails and telephone calls over a period of time, I haven't managed to get a response from Emerald however others have as the unit appears to be very popular.

Others

There are other ECU options available, however many, such as the Webcon Alpha and the Dunnell aren't user programmable, so can be more difficult to get mapped, requiring a visit to an approved rolling road or the manufacturer.

Ignition and Injection Maps

When you have your programmable ECU, you will need to have an ignition map and possibly an injection map installing on it for it to work. This is done via the ECU software and programming lead.

I am compiling a list of maps for different specification Zetec engines. Please click here to access my library of Zetec engine maps.


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