Many Bronco owners are satisfied with their engine power output.
For those of you who are not, you have probably already considered
adding a new cam, exhaust or heads/intake. In 1986, Ford switched
to EFI on 5.0 Bronco engines. 1987 brought the first EFI 5.8. The
EFI Ford used for almost all Broncos is what is called speed
density. Speed density EFI uses a manifold absolute pressure sensor
(MAP), a throttle position sensor (TPS), an air intake temperature
sender (ACT) , and the knowledge of the factory intake/exhaust
tract which gives your engine certain volumetric efficiencies over
it's RPM range. This allows the EEC-IV (Electronic Engine Control
IV) to determine the mass (different than volume) of air coming
into your engine, and hence the amount of fuel needed to go with
this air. Speed density EFI also uses what is called bank fire
injection. 4 injector are fired at one time on each side of the
engine (only 2 wires for firing injectors from EEC-IV).
So why do I need Mass Air EFI?
The problem with Speed Density EFI is, that changing many of your
engine components, will change this volumetric efficiency. Speed
density can detect some changes with it's MAP, TPS, and ACT
sensors. It can not detect that you have changed the volume of air
coming in and out of the engine. This is where mass air comes in. A
mass air sensor directly reads the mass of air (or number of
molecules of air). By doing this, it can detect the changes in the
volume of air, in addition to it's pressure and temperature. Mass
air EFI is usually what is called SEFI (Sequential Electronic Fuel
Injection), which has one separate wire for each injector and fires
them twice for every power stroke of the engine. This makes the
injector timing more accurate and will help emissions along with
power.
So what mods can I do?
Speed density EFI will usually run well with just about any exhaust
modifications. There are also mild head/cam swaps designed for
speed density EFI systems. One list member is running the
stock speed density computer/intake with Windsor Jr. heads and a
stock 351W lightning cam. Claim is that it runs very well and the
key is the lobe separation of the cam, which should be kept above
113 degrees. Lighting Cam specs:
Anything else, like moderate to wild cam/head/intake swaps or any
forced induction will usually require a swap to mass air. Some guys
on the Mustang 5.0 lists have run fairly wild combos on speed
density and have had no problems, others have had huge headaches
with the same combo. Therefore, a swap to mass air should be in
your plans (at least your backup plans) if you plan on any engine
mods. This swap can be bought from various sources, but it costs
$1000 or more.
Is that all I need?
Keep in mind, that while swapping in mass air will help when doing
modifications , once you get beyond the flow capabilities of your
stock injectors and/or mass air flow meter, you will need bigger
one's. The stock mass air sensor is pretty big, so you will
probably run out of injector before needing a mass air sensor swap.
You can get mass air flow meters that flow more and/or are
calibrated to bigger injectors. This way of doing it is again a
gamble, as sometimes it works, but many times it does not. Part
throttle timing curves can be disrupted tremendously by trying to
fool the EEC-IV with recalibrated mass air sensors. This usually
leads to massive part throttle pinging and possible engine damage.
Piggyback chips can be custom done for your application (about
$225) and will allow running bigger injectors (or even bigger mass
air meters) with the same mass air voltage curve that the stock
mass air sensor uses. Check out our Sources listed at the end of
the article and their websites for more info on the "whys" of
piggyback chips and what they can do.
So, how do I do it?
Below is information I have gotten from the Bronco mailing list or
found myself in regards to this swap. I have not done this swap and
I do not even own an EFI equipped Bronco.
All transmission controls have 8 wires except 94-95 5.0's which
are supposedly mass air and have 9 transmission control wires. Not
sure if this is a CA. thing or not. 89 could have an E4OD trans,
which is also controlled by the EEC. It seems all EEC's that
control the E4OD have the same number and color wires, except as
noted above. Above 89 should have an E4OD (E).
Mass air conversion from 95, 5.8 processor (processor number
BIO0, last digit zero!) would require running 6 new wires for
injectors. Pins 12, 13, 14 ,15 and 38, 39. 2 new wires for mass air
sensor at pins 9 and 50. Other mass air sensor wires are power and
ground. Pin 2 must be run to brake switch. Switch pin 28 to 18 and
19 to 9 (diagnostic wires). May have to add second O2
sensor, relocate pin 29 to 43 and run pin 44 to second
O2 sensor. Stock mass air sensor on 95 CA models is 70
mm, which should flow well over 400 HP.
96 models all had mass air, but they use Fords' EEC-V, which is
under the rules of OBD II (On Board Diagnostics II). this EEC is
much more sensitive to engine mods and is also 104 pins, vs 60 pin
on the EEC-IV. Not a good candidate for a swap.
It is highly recommended that any swap be preceded by ordering
Fords factory electrical diagrams for what you have and what you
want to swap in.
87-89 (or any year) models that do not have electronic
transmission controls, may have problems using an EEC that wants to
control a transmission. This can be fixed by using a 5 Speed
Mustang EEC and a piggy back chip. The piggy back chips can even
control engine size, so a 5.8 (or even a 410 ci) won't be a
problem. These EEC codes should be OK for the swap. A9L, A3M, A3M1,
D3D1, X3Z, S0Z. Use of Mustang EEC may require swapping several
pins for cruise control wiring. It will also require the wiring
changes described in part 2, mainly converting the injectors to
SEFI, running new O2 sensor wiring and running new mass air
wires.
It was also suggested that a "Lightning" truck EEC
(processor number c3P2) may be used as it is mass air, but can
double the amount of fuel that it provides as it bank fires the
injectors twice for every power stroke, effectively making 19 lb/hr
injectors seem like 38 lb/hr. I would say a piggyback chip would be
more satisfactory than this method, but it is another idea.
Speed density EFI uses bank fire injection. Due to this, the
distributor supplied with this motor does not need to know when it
reaches the number 1 cylinder. Converting to SEFI requires that the
EEC-IV know where the number 1 cylinder is. The distributor may
need to be changed to the one supplied with SEFI engines that has
one smaller tooth in the hall effect sensor built into the
distributor. Some list members have converted to mass air using a
mass air kit and have had no distributor problems. Early EFI
owners, especially 86-87, should have the excitor ring on
distributor checked and make sure the #1 identifier is present in
your distributor.
Johnson
Motorsports
128 Carondolet
Court East
Mobi le, AL
36608
(334
)344-2621
Comments from our Readers
Delray Dobbins / Columbus, OH, UNITED STATES
Posted Mar 04 2008 12:24PM
I would like to contact the list member running a lightning cam in a speed density 5.8. I have a 94 F150 5.8 ext cab flareside running a 6 lb boost vortech blower. Eng has 173K miles. I plan to rebuild the engine this spring and am looking for mods w/o getting into a mass air conversion. Thanks. Kind Regards.
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Posted Mar 04 2008 12:24PM
