FAF268.tech_ by ajizai


									fasttech / tech / Bosch K/KE JEtronic inJEction /                                                                                                                                                            fasttech

 Part 1

    Bosch fuel                                                                                                                                                                                                           warm-up

                                                                                                                                                                                                                          to other
                                                                                                        injector                                                                                                          injectors

                                                    Having worked
    This month Stu starts his series looking at     as a tuner for 17
                                                    years, Stewart ‘Stu’
    Bosch K/KE Jetronic fuel injection.             Sanderson is one
                                                                                                                                                                         sensor                                           regulator

                                                    of the most-
                                                    respected names                                                                          air valve
                                                    in the business.                                                       cold start
                                                       A Level 5-trained
                                                    technician, in the                                                                                                 accumulator                                         fuel
                                                    past Stu has worked                                                                                                                                                    tank
                                                    for a Ford Rallye Sport                                                                                                                       filter
                                                                                                                                                         fuel pump
                                                    dealer, a well-known
                                                    specialist and various
                                                                              Bosch k and ke jetronic systems
                                                    tuning companies.
                                                                              are largely mechanically Based
                                                       Then seven
                                                    years ago he joined
                                                    forces with Kenny
                                                    Walker and opened
                                                    up Motorsport

                                                    Developments near                 his month I’m starting my       unit handles fuel distribution        the fuel distribution unit (often       injector caters for extreme cold
                                                    Blackpool (01253                  multi-part Bosch K and KE       mechanically, and the injectors       known as the metering head)             start. Any fuelling adjustments
                                                    508400, www.                      Jetronic article. Bosch K is    open under pressure and stay          in the engine bay. It is delivered      required for normal cold start and
                                                    remapping.co.uk),         fitted to Escort RS1600is, XR3is,       open, injecting fuel constantly.      at a regulated pressure and any         warm-up periods are dealt with
                                                    specialising in engine    Sierra XR4is and 2.8i XR4x4s,           Modern counterparts use               excess fuel is returned to the          by adjusting the control pressure
                                                    management live           whereas the Bosch KE system             mechanical solenoids as injectors     tank. Depending on the engine’s         within the metering head. The
                                                    remapping, as well as     is fitted to all Escort RS Turbos.      that can be switched on and off at    coolant temperature, the correct        auxiliary air valve increases
                                                    developing a range of     That’s a whole generation of fast       will by a computer that contains      amount of fuel is delivered via the     the idle speed if necessary
                                                    Evolution chips which     Fords, and there are still a great      maps for such operations.             injectors to the engine.                and the ignition system is the
                                                    are now sold all over     many of them in operation today.                                                 The injectors on this system         conventional distributor and rotor
                                                    the world.                   The system is unique in its          UnDerstanDing Bosch                   spray fuel continuously (the K in       arm system. Let’s break it down
                                                       He’s also jointly      operation and leaves many garage        K anD Ke                              Bosch K and KE means Konstant)          into component form now
                                                    responsible with          technicians and performance             As with all fuel injection systems,   in a fine atomised spray into           and see how each piece
                                                    Webmaster, Petrucci       specialists baffled when it             I believe that the only way to        the inlet manifold. A cold start        actually works.
                                                    for www.passion           goes wrong, as they have been           understand them properly is to
                                                    ford.com. Started in      trained in normal EFi. We have          start breaking them down into
                                                    2003, it’s grown          cars brought to us on a trailer         component form and look at what          Fuel pump
                                                    rapidly from a few        quite regularly from garages            each item does and what effect it
                                                    friends contributing,     and sometimes even Ford main            has on the system’s operation as         The fuel pumps          a pressure relief
                                                    to one of the biggest     dealers when they can’t get to          a whole.                                 used are of the         valve that lifts
                                                    Ford communities on       the bottom of a problem with an            The easiest way to understand         high-pressure roller    off its seat at
                                                    the web. His new          aging Bosch KE system.                  Bosch K and KE is to look at Bosch       cell type. The fuel     around 8bar to
                                                    forum, www.fordrs            Applying normal EFi practices        K components in depth first and          enters the pump         release the pressure
                                                    forums.co.uk, is also     to Bosch K and KE will often            then see what differences were           at one end and is       should the filter, the
                                                    up and running.           make the system run worse               brought in to make it essentially        compressed by a         fuel lines or any
                                                       Stu’s enviable         than it did before you tried to         Bosch KE. The Bosch K section            number of rotating      other foreign
                                                    knowledge of the          repair it. If you’re willing to blank   will be of most use to XR owners         cells that force it     body cause
                                                    workings of modern-       your mind of conventional fuel          but will also benefit the RS Turbo       through the pump at     an obstruction.
                                                    day Ford performance      injection practices, I will attempt     owners. The KE section will be of        very high pressure.        There is a
                                                    engines means that        to educate you as to how the            more interest to those with Escort       They are capable        non-return valve
                                                    every month he’s just     system works and what its               RS Turbos as your cars needed            of producing a          located on the other
                                                    the man to explain        common problems are.                    the electronic enrichment system         pressure in excess      end of the pump
                                                    how and why things                                                specific to KE, mainly to cater for      of 8bar (115psi) with   where the fuel
                                                    work, and most            Differences from                        forced induction.                        a delivery rate of      comes out, which
                                                    importantly how they      conventional efi systems?                                                        around 4-5 litres       stops the system
                                                    can be improved.          The biggest difference with Bosch       Bosch K Jetronic                         per minute.             pressure from
                                                                              K and KE compared to today’s            With these systems, the fuel                Within this          dropping too quickly
                                                                              electronic fuel injection systems       is delivered in a conventional           type of pump            when the pump
                                                                              is that it’s largely mechanical         manner from the fuel tank, via a         there is always         is stopped.
                                                                              in operation. The distribution          rear mounted fuel pump, up to

 0 1 1 2 august 2008 Fast Ford                                                                                                                                                                             Fast Ford august 2008 0 1 1 3
fasttech / tech / Bosch K/KE JEtronic inJEction /                                                                                                                                                                                                                                             fasttech

       Fuel pressure and                                                       Airflow SenSor                                                                                                                                                                                           fuel filter
       pump power supply
                                                                               The fuel goes to the metering        hoses or blow them off, resulting                                                                                                                                   This is next in line. It must be
       The normal operating pressure       sparks and arcing at this           unit next, but we will discuss       in an engine that will not start.                                                                                                                                   kept clean at all times as the
       within the fuel system is           pressure but, while this sounds     that part later. Let’s instead          The airflow sensor plate is                                                                                                                                      extremely fine tolerances
       approximately 5bar. At this         quite dangerous, the absence of     move onto the airflow sensor.        mechanically hinged and the                                                                                                                                         within the Bosch K and KE
       pressure the current draw on        oxygen means that there won’t       This is one of the most crucial      other side of it is connected to                                                                                                                                    Jetronic system mean that
       the fuel pump is between 5 and      be an explosion! The supply         parts of the system. The airflow     the metering unit’s control                                                                                                                                         damage can easily be done if
       8amps. Interestingly, the fuel      voltage to the pump is 13volts      sensor is located under the          plunger. As the airflow moves                                                                                                                                       dirt is allowed to enter the
       passing across the fuel pump’s      fed directly to the pump via the    air filter housing and this unit     the sensor plate this                                                                                                                                               metering head. The filter is a
       armature will be subjected to       fuel pump relay.                    is directly responsible for          subsequently moves the                                                                                                                                              large metal canister with
                                                                               measuring the air going into         metering unit’s control plunger,                                                                                                                                    different fittings at both
                                                                               our engine and helping the           which is situated directly in                                                                                                                                       ends to avoid the unit being
                                                                               metering unit decide how much        the centre of the metering unit.                                                                                                                                    installed incorrectly and
                                                                               fuel needs to be injected.           The higher the lift of the plunger,                                                                                                                                 compromising efficiency.
                                                                                  The sensor housing is conical     the greater the amount of fuel                                                                                                                                         A visual inspection of
                                                                               in shape and has an airflow plate    will be delivered to the fuel                                                                                                                                       the filter internals isn’t
                                                                               fitted into it, which is drawn       injectors. (You will read more                                                                                                                                      possible so change it at the
                                                                               downwards (Bosch KE) or              about the plunger operation in                                                                                                                                      recommended intervals.
                                                                               upwards (Bosch K) as air             the section below.)                                                                                                                                                 Personally, I recommend high-
                                                                               demand is increased. The                To allow fine adjustment of                                                                                                                                      power engines have these
                                                                               amount it moves is directly          the fuel mixture a 3mm Allen                                                                                                                                        changed every 6000 miles.
                                                                               proportional to the amount of        screw is located within the                                                                                                                                         (Remember that standard
                                                                               airflow entering the engine.         airflow sensor. This screw alters                                                                                                                                   power cars flow less fuel
                                                                                  The shape and angle of the                                                                                                                  Spotting the difference between K and KE                  through these items so have
                                                                                                                    the relationship between the
                                                                                                                                                                                                                              is quite easy. K has the air filter underneath
                                                                               conical area of the housing          airflow sensor arm and the                                                                                the airflow sensor, and KE has it above                   higher service intervals.)
        Fuel pump has direct 13volt feed                                       determines the amount of lift        control plunger. Turning the
        and supplies 5bar of pressure
                                                                               per pound of air. The resting        screw clockwise enriches the
                                                                               position of this plate is            mixture and anti-clockwise            fuel DiStribution
                                                                               approximately level with the         weakens it. It should be noted
                                                                               bottom of the cone; this is          that the screw should be turned       This is the heart of the Bosch K       barrel, and it is through these       small amounts, thus moving the                 The K and KE metering heads

       Fuel accumulator                                                        adjustable by bending a small
                                                                               clip/spring that acts as a stop
                                                                                                                    in very small increments and the
                                                                                                                    Allen key should always be
                                                                                                                                                          and KE Jetronic fuel injection
                                                                                                                                                          systems. It is in charge of taking
                                                                                                                                                                                                 openings that the fuel passes
                                                                                                                                                                                                 through to the injector lines and
                                                                                                                                                                                                                                       plunger also by a very small
                                                                                                                                                                                                                                       amount, allowing only a small
                                                                                                                                                                                                                                                                                   differ in fitment and operation and
                                                                                                                                                                                                                                                                                   are NOT interchangeable.
       This is the first of the            duration that the engine is         at the bottom of the unit. The       removed before the engine             the fuel in from the fuel filter and   onwards to the injectors.             amount of fuel flow through
       components in the fuel system       running, the diaphragm will be      purpose of this spring is to         speed is raised or damage may         delivering the correct amount to          The width of these metered slits   the slits. As the throttle is
       after the pump. This unit has an    against its stop within the         allow the flap to move beyond        result to the unit.                   the fuel injectors. As the airflow     is only around 0.2mm across. This     opened further and the volume
       important role in the operation     spring’s chamber. When the          its neutral position to allow                                              sensor plate is lifted by the          dimension, together with the          of fuel required is far higher,
                                                                                                                     Airflow sensor is one of the most
       of the Bosch K and KE Jetronic      engine is stopped and all of the    excessive pressure to escape if                                            engine’s inducted air, the control     plunger height itself, will           the airflow plate moves further,
                                                                                                                     crucial parts of the system
       system. Its first job is                 non-return valves close, the   the engine was to backfire,                                                plunger is lifted proportionately,     determine how much fuel is            thus moving the metering
       to help smooth out any                     spring pressure against      passing a large volume of air                                              exposing small slits within the fuel   delivered to the fuel injectors for   plunger further and exposing
       pulses in the flow of                          the diaphragm will       back into the air filter                                                   distribution unit’s barrel assembly.   supply into the engine. At low        more of the slits to allow more
       the fuel. This is                               maintain fuel           housing. If the                                                            The barrel assembly has four small     engine speeds the air drawn into      volume of fuel to flow to the
       achieved by passing                                pressure and         system did                                                                 slits (6/8 on six and eight cylinder   the engine is likely to be minimal    injectors to keep the airflow
       the fuel through a                                 overcome any         not have                                                                   cars) that are machined into the       so this air flap will move only       ratio correct.
       series of baffles                                  slight seepage.      this facility
       and into a chamber                                 After a journey,     the
       giving it slight                               when the engine is       pressure
                                                                                                                                                            sensor plate moves as                                                      a         B           a
       capacitance and a much                       switched off, the          could
                                                                                                                                                            air demand is increased,
       smoother flow.                               underbonnet temp           split                                                                        altering the amount of                            fuel
          Its other, and possibly                  increases causing the                                                                                    fuel Being delivered                              distriButor
       more important, role is to                  fuel in the lines to heat                                                                                                                                                                                                   control
                                                                                                                                                                                                                                                                               plunger                         c
       maintain pressure within                  and it attempts to
       the system when the fuel pump       evaporate. Maintaining the
       has been switched off. This is      pressure eliminates this
       achieved by the accumulator         problem and ensures a clean         The lift on the plunger in the       move the plunger. The less
       spring and diaphragm pushing        start when the vehicle has been     fuel distribution unit is            pressure we have, the easier                                                 idle mixture
       against the fuel. For the           standing with a hot engine.         proportionate to the volume of       it will be. This is the case with                                            adjustment
                                                                               air passing into the engine via      cold starts. Bosch devised a
                                                                               the airflow flap. However, the       way to make the air flap move
                                 diaphragm                                     amount of fuel required when         further when cold for any given
           chamBer                                                             the engine is cold is different to   volume of air than it does                                                                                                                                                              push up
                                                                               when hot, and so we have a           when it’s hot with the same                                                                                                                                                             valve
                                                                               system that can exaggerate the       volume of air using the warm
                                                                               fuel delivery by adjusting the       up regulator.                                                       sensor
                                                                                                                                                                                        plate                                                                                                     primary
                                                                               pressure acting on the top of           It’s worth noting that Bosch                                                                                                                                               pressure
                                                                               the plunger, allowing it to move     K and KE metering heads are                                                                                                                                d    e     f       regulator
                                                                               further for less airflow.            different in how the pressure
                                                                                  Think of the pressure on          is regulated for enrichment                                                                                                                                          a – to fuel injectors
                                                                                                                                                                                                                                                                                         B – to warm up regulator
                                                                               top of the plunger as a spring.      and cold start, but the basic                                                                                 main lever                                             c – from warm up regulator
                                                                               The more pressure we have            theory of operation is very                                                                                                                                          d – to cold start injector
                   spring                                                                                                                                                                                                                                                                e – from fuel filter
                                                                               there, the harder it will be to      much the same.                                                                                                                                                       f – return to fuel tank

 0 1 1 4 august 2008 Fast Ford                                                                                                                                                                                                                                                             Fast Ford august 2008 0 1 1 5
fasttech / tech / Bosch K/KE JEtronic inJEction /

         warm-up regulator will
         enrich air/fuel mixture                          a                         B       c                         pressure
         when the engine is cold
                                                                                                                      This is the pressure that is
        a – vacuum connection                                                                                         seen within the system
        B – return to fuel tank                                                                                       between the fuel pump and
        c – control pressure
                                                                                                                      the fuel metering head. The
                                                                                                                      primary pressure regulator,

                     electric                                                                      valve              situated within the metering
                     heating                                                                       diaphragm          head, determines this
                                                                                                                      pressure. When the required
                                                                                                                      pressure is obtained, the
                                                                                                                      plunger within the regulator
                                                                                                                      lifts off its seat and excess
                                                                                                                      fuel is returned to the tank.
                                                                                                                          Due to the nature of its
                                                                                                                      operation, this system will
                                                                                                                      automatically compensate
                                                                                                                      for different fuel demands
                                                                                                                      under different conditions. If
                                                                                                                      the fuel requirement is low
                                                                                                                      at engine idle, the plunger
                                                                                                                      will lift and return a greater
                                                                                                                      volume of fuel back to the
                                                                                                                      tank than when the demand
                                                                                                                      is higher, when a smaller
                                                                                                                      amount of fuel is returned.
                                                                                                                          On Bosch K systems,
                                                                                                                      the system’s pressure is
                                                                                                                      determined by the tension
                                                                                                                      of the spring reacting
                                                                                                                      against the plunger. If a
                                                                                                                      higher pressure is required,
                                                                                                                      small shims can be placed
                                                                                                                      behind the spring, changing
                                                                                                                      its effective length and
                                                                                                                      increasing the pressure. A
                                                                                                                      shim of approximately 2mm
                    Bi-metal spring                             lower stop                      diaphragm             will increase the pressure by
                                                                                                                      about 10psi. Bosch KE has
                                                                                                                      an electronic system to
                                                                                                                      regulate pressure and we
       warm-up regulator (BoscH K only)                                                                               will discuss that later.

       This relatively simple device       comprises of an inlet and outlet       almost uninterrupted. As the
       is responsible for controlling      port, a stainless steel shim, a        bi-metallic strip is heated, by
       the amount of fuel delivered        bi-metallic heated strip and a         either its heater element or
       to the engine during its warm-      spring. The input to the warm-up-      natural heat soak from the
       up period.                          regulator flows into a small           engine, the downward pressure
          This device, depending on the    chamber in the top of the unit,        acting on the spring is gradually
       engine temperature, varies the      its return is through a small          decreased, increasing the force
       pressure acting on the control      drilling and back to the metering      of the spring, which in turn
       plunger in the metering head. As    head. By controlling the flow          increases the control pressure.
       such it provides a very effective   of fuel back to the metering              The voltage supply to the
       method of fuel enrichment.          head it can directly control the       regulator is from the fuel pump
          The control pressure within      pressure at the top of the             relay. It is fuel system powered
       the metering unit is tapped off     metering plunger.                      as opposed to ignition system
       from the primary pressure circuit      With a cold engine the flow         powered for good reason. If the
       in the metering head’s lower        must be fairly free giving a lower     driver sat with the ignition on
       chamber through a tiny              pressure on top of the plunger.        but without the engine running,
       restrictive hole that gives it      This will allow a higher lift of the   all enrichment could be removed
       the ability to differentiate        plunger by the air flap for any        before the engine was ever
       between the two pressures. A        given volume of air passing            actually started, as the bi-
       flexible pipe then connects the
       control plunger gallery to the
                                           through it, which consequently
                                           will enrich the mixture under
                                                                                  metallic strip would be heated
                                                                                  prematurely and the driver
                                                                                                                      neXt montH
       warm-up-regulator and returns       these conditions.                      would not benefit from the cold
       the fuel back to the metering          The internal bi-metallic strip      engine enrichment.                  More on the Bosch K, and how
       head to a connection next to        exerting a downward pressure              The two pipes that connect       the system was improved with
       the primary pressure regulator’s    on the spring decreases the            to the warm-up-regulator            the KE version and its extra/
       transfer valve.                     pressure acting upon the shim to       have different sized ‘banjo         different parts. Plus, how the
          The internals of the warm-up-    create the free flow; this lower
                                                                                                                      electronics integrate in this
                                                                                  unions’ to avoid them being
                                                                                                                      mechanical system.
       regulator are quite simple. It      force allows the fuel to flow          connected incorrectly.

 0 1 1 6 august 2008 Fast Ford

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