Just to reaffirm Mickey Mouse's view of engineers.

There are two main styles of driver circuits so there are two main styles of
injectors: There is a Saturated Circuit style as well as a Peak and Hold
style. Before going into the differences, keep in mind that the two are not
compatible. Interchanging the different style injectors can result in slower
delivery rate, overheating of the injector or driver and even engine damage.

Saturated Circuit drivers are very inexpensive, simple, and reliable. This
type of driver works by supplying 12 volts to the injectors and the ECU
turns it on and off to establish a fuel injector pulse. In general, if an
injector has a high resistance specification (10-16 ohms) the ECU uses a
12-volt saturated circuit driver to control it. This means that the current
flow in the driver and injector circuit stays low keeping the components
cool aiding in a long life. The downside of a Saturated Circuit driver is
that it has a slower response time (and closing time) than a peak and hold
type. This slower time can somewhat decrease the usable operating range of
the injector energized by this driver. An injector operating on a saturated
circuit driver typically has a reaction time of 2 milliseconds while a peak
and hold driver typically responds in 1.5 ms. These injectors will be high
impedance due to many turns of smaller wire to obtain a high resistance.


Peak and Hold types of injectors and drivers may also be called current
sensing or current limiting. They are more expensive and complex than
saturated circuit drivers, and are not generally used with domestic
production ECUs. Most high flow injectors are low resistance (1.5-5 ohms)
and use a peak and hold driver to activate them. The Peak current is the
amount required to as quickly as possible open the injector, and then the
lower Hold current rating is used to keep it open for as long as the ECU
commands. These require the higher current to keep the opening and closing
time of the injector stable at the higher fuel flow rate. With this type of
driver, 12 volts is still delivered to the injector, but due to the its low
resistance, the current in the driver circuit is high. Using Ohm's Law we
can calculate the current rating (12v/2 ohms = 6 amps). This is substantial
current flow and a Saturated Injector cannot handle it. The drivers also
come in two values; 4 amp peak/1 amp hold, and 2 amp peak/0.5 amp hold. Even
though 6 amps may be available to operate the injector, the maximum it is
allowed to reach is 2 or 4 amps, depending on the driver’s current limit.
The hold current is determined either by an analog current limit or pulse
width modulation. The advantage of pulse width modulation is that there is
much less energy lost, in the form of heat. These injectors will be low
impedance due to the fewer turns of larger wire.

Both of these circuits basically fire the injectors with rectangular pulses
of varying length.

regards,
C5Phil

In article <PM0003C9E26648E293@arbitrary.net.digitex.net>,
LanceM <alancemorREMOVE@yahooCAPS.com> wrote:

> High impedance, PFI pintle-style saturation injectors
>
> I've seen two waveform references: the first one, which is what I'm
> seeing on my scope, shows that the (negatively controlled) "on" pulse
> doesn't go to full ground, but rather just down to ~1.5 V (this seems to
> imply a Peak and Hold, rather than a saturation injector [or maybe
> that's more of a distinction of event duration]?)

On a peak and hold, you'd probably see the signal go to full
ground first, then step up to the 1.5 volt value.

As a general rule, peak-hold injectors will be low impedance
and typically used in TBI systems, full saturation injectors
will be higher impedance and used in PFI type systems.
(it's all about current control)

> The second waveform ref sample shows the injector opening with a full
> ground.
>
> Are both possibly correct, and just due to slightly different injectors
> and/or ECMs?

Yes.

Unfortuneately, not everything can be cataloged, not
everything is going to have printed known good examples,
which is why familiarization with test equipment and its
results is best done ahead of time on stuff that you know is
working correctly. (doesn't help your situation much 8-(

Many imports, especially the older ones used a ballast
resistor(s) in series in the injector circuit, perhaps this
is the result of what you're seeing with your 1.5 volt
ground anomoly? (I don't see the injector circuit shown on
the EZK URL)

Injectors
This article deals with different types and styles of injectors and mounting them.

Impedance

Injector impedance describes the electrical resistance of the solenoid windings. These are usually grouped in two categories:

Low- 1.7 to 3.0 ohms
High- 10 to 16 ohms

There are some exceptions to this, notably the Bosch 803 injector used on the Porsche 944 turbo which is 4.7 ohms. Most manufacturers have used both types at one time or another. The trend lately is to use high impedance types in most production cars. The best way to determine impedance is to put a digital ohmmeter across the two electrical connections and see what it reads. The primary advantage of low impedance injectors is a shorter triggering time. When large injectors are fitted to high output engines, low impedance injectors will often give a better idle quality because of this fact. The primary advantage of high impedance injectors is the fact that less heat is generated in the drive circuit and often no external resistors are used.

Originally posted by cewrx7r1
I have only run stock injectors with the PFC, 550/1200s, but I do know about electronics, so here are some basic facts.

First the basic law of DC electricity. Injectors runs DC but because it is pulsating at a high rate, it does have some AC affects but we will omit these(impedance, capacitance, and reverse EMF).

E(volts) = I(current) * R(resistance).

The stock resistance is 13.8ohm for a Mazda injector.
I do not know if the ECU supplies 12 or less voltage so lets use 12 volts. I know the alternator supplies almost 14 volts but this is irrevalent for our discussion as is the supply voltage. The laws still work the same.

Thus omitting the resistance of the wiring an asumming it is 0 ohm, we have 12 volts = I * 13.8 ohms.
Or I(current) = 12/13.8 = .87 amps.

watts(power) = I * E = .87 *12 = 10.44 watts.

Thus this is the basic load range the ecu was made to run per injector.The circuits might be able to run hicher current without problems but I do not know their safe maximum current/power. So now to your questions.
***************************************
"So does the PFC run low impedance injectors with resistors correctly or not?"
Yes it can if the extra current flow is within its design range. This will have to be answered by someone who has actually done it. It would work up to the point of overheating then burn up if the load was too high.
Most like would happen at higher fuel load requirements as the injector cyclic rate goes higher.

"Is using the resistors just a way to make them work?"
They will work anyway up to the point of overloading the ecu control circuits. The added resistor is used only to keep max current flow within the save range for the ecu circuits.

"What is the difference in the way they operate/distribute fuel?'
None except a large injector injects more fuel.

"If I am using the datalogic I can completely bypass (not install) the resistors right? "
Might burn up/overload the ecu.

"How does it do this are they (10 ohm 20 watt resistors/10 ohm 10 watt resistors) built into the datalogic? "
Really do not understand this question. Both of these resistors will have the exact same affect if placed inline with a lower resistance injector. The diff is there power/heat handling capacity. 10ohm/20watt can handle twice the current of a 10/10. 20 watts is twice the value of 10.

"How much better is it to use the 1300s instead of low impendence 1600s, assuming that there is no issue with the 1300s sticking or not working properly?"
The question really is, what is the power requirement for a lower than 13.8 ohm injector. If the installed resistor reduces total current flow such that the power used by the injector is too low, it might not function at the full rated flow rate. The R value given in E=IR
can be (R = R1 + R2) R1 being the risistor and R2 being the injector. If R1 = R2 than each drop half the power of the total circuit which might be too low for the injector.
You will need to know the operatinal range for the low resistant injector. It is never a problem with a higher resistance injector becaue it will alwasy get it max required current/power with out overloading the ecu.

"I was talking to Ralf Friend (Exessive motorsports, groundzero) and it sounded like he was saying that 1600s work but are just not as accurate at putting in the fuel as high impendence1300s would be (my interpretation of what he was saying)'
See above.


"I am running the GT 35/40 and was thinking about using 850 primaries and 1300 secondaries. These will work for my HP goals but I am not sure if using 1300s is the right path, because I have read a couple of posts that say stay away from the bored out 850s to 1300s."
Bullshit fairy tells. Anything might not work sometimes if not correctly made or modified.

"What will be the advantage to running the high impendence over the lows if any?'
Less load on the ecu this less heat build up.

Fuel Injectors:
The fuel injector is a fancy name for an electric solenoid valve. It is a valve that when you apply electricity it will open and allow fuel to flow through. The catch is that it is a very precision valve. The injector must flow a precise amount at a specific pressure and be able to open and close very fast. The ECM controls the injector turning it OFF and ON for different amounts of time depending on how much fuel the engine needs. There are several different shapes of injectors for different applications but they still work the same way. Some operate at different pressure ratings. They range 12 to 20 PSI for most throttle body systems and 40 to 50 PSI for most port injection systems. Injectors have different electrical resistances. Throttle body injectors are usually 1.2 or 2.4 ohm and are considered Low impedance. Port injectors can be either 2.4 or 12-16 ohm with the 12-16 ohm injectors being considered high impedance. High impedance injectors are general purpose and used in many production cars and are driven with what is called saturation drivers. The Low impedance injectors are usually found in high performance injectors or injectors used on high RPM engines and require a Peak and Hold type of driver. High impedance injectors can be used on either type of driver, but Low Impedance injectors cannot be used on a Saturation driver. Injectors also have a defined “spray” pattern. Most Throttle body injectors spray in a wide fan spray while a Port injector sprays a narrow pattern that is directed at the open valve. They can be interchanged but some performance may be sacrificed. The last point about injectors is their flow rate. Different size injectors are needed for different engines. It is kind of like changing jets in a carb. Most production injectors are rated at 15 to 30 pounds of fuel per hour. This means that if the injector is open full time that it will actually flow this many pounds per hour of fuel. There are about 6 pounds of Gas per Gallon. Higher flow injectors are available for racing up to 200 lb./hr for alcohol racing applications. A rough rule of thumb is that you can get 2 HP for every lb./hr of fuel. This means if you have 8 20lb injectors then you have the ability to generate a maximum of 320 HP. If you would want more Horsepower than you would need larger injectors and the corresponding engine modifications.

***IF using LI injectors on a HI harness, you must splice into the harness, at each injector lead (for a total of 4) 10 ohm/10watt resistors available at radio shack for a couple of bucks. Doesn't matter which wire of the 2 per injector you splice to, polarity isn't an issue here. This bumps the LI resistance up to acceptable load for the ECU to see.