When a low impedance injector is installed without a resistor pack, certain elements of the system are much more likely to get burned out, as the current will not be controlled properly. The junction temperature is the temperature of the transistor that is embedded inside the package.
The greater the current, the greater the temperature, and the more likely the reliability will be affected. While temperature is a pretty straightforward measurement, reliability is not, and can take a bit of time to measure. High impedance injectors, as mentioned above, are much more common in use today. The drive circuitry for high impedance injectors is quite simple and referred to as a saturated driver circuit.
The driver circuitry used with these injectors is referred to as a Peak — Hold type of circuit, and is much more complex and therefore expensive than the saturated driver circuits in high impedance injectors.
In this kind of system, the driver circuit allows a high current to exist for a short time to turn on the injector quickly. A saturated signal is a simple signal used to operate high impedance injectors. A single intensity signal is sent to a fuel injector which causes the valve to open and remain open until the signal has ended. This means that low impedance injectors are no longer the peak of performance when considering fuel injectors.
How do I know if my injector is low impedance or high impedance? You can measure the resistance across the two electrical terminals of the injector. If the resistance is between 1. If the resistance is between 8 and 16 Ohm you have high impedance injectors. Many aftermarket ECUs are able to drive both low and high impedance injectors. If you have a concern regarding which you should choose you should contact the manufacturer of your ECU or refer to its installation manual to determine the best choice.
If I have a choice, why would I choose a low-Z or high-Z injector? This meant that at higher flow rates and lengthier duty cycles low impedance injectors would outperform their high impedance counterparts. Since so many of the performance injectors back then were low impedance injectors and they were actually better than their high-z equivalents, the common belief which still lingers today though it is no longer correct is that low-z injectors are the best for your high performance vehicle.
Thanks to this newer technology the current high-z injectors are more linear throughout their pulse range; they are able to repeat shorter pulse widths consistently which means they can provide excellent part throttle and idle characteristics, and operate at higher maximum operating pressures.
These facts make choosing one of the new high-z injectors we offer a no-brainer if your ECU and fuel system setup allows you the choice, and the budget will stretch to the slightly higher average cost. How much flow can I get from low impedance vs. The latest injector technology has turned this area upside down in the last few years! These new technology high-Z injectors display great linearity throughout the pulse range and have fantastic short pulse width repeatability which results in stock-like idle and superior part throttle characteristics from these large injectors.
The older fat body style low impedance injectors 1. Since this method put less total current into the coil, the coil heated up less and was therefore more reliable. High impedance injectors 10 to 16 Ohm are triggered by a low typically around 1. Why do I have a resistor pack in my car? There are quite a few aftermarket ECUs although not all that will be able to provide both saturated and peak and hold injector drivers.
Make sure you set your ECU to match the type of injectors you purchased! Vehicles that have low impedance injectors AND resistor packs have ECUs that use a saturated signal to operate low impedance injectors.
You may know, or have read earlier in our FAQ How do I know if my injector is low impedance or high impedance? The way they solved the problem was to add a resistor box into the fuel injector harness, thereby increasing the resistance in the circuit to the higher value needed to prevent the ECU injector drivers from overheating due to excessive current draw.
While the injector will operate normally with just about any fuel, you do have to take some precautions with certain fuels. However, in the performance world we need to take a few extra precautions since we do a few things differently than the typical soccer mom.
That means that if the fuel stands for a while, it will draw water from the air and potentially start corroding rusting parts that are not protected. In any injector it is necessary for some of the internal parts to be made of ferrous metals since the electromagnet would not be able to open the valve if it were non-ferrous. These ferrous parts can corrode rust if not protected. If a vehicle is only run occasionally or the injectors are removed from the sealed fuel system, the injector parts can be exposed to conditions they are not designed for and cause the injector to lock up or change the flow rate.
Under most circumstances we are able to clean these injectors and return them to their proper operating condition, but in some cases the effects can be terminal see cc care. As a result, these solids interact with the gasses and other suspended chemicals in the intake to form solid deposits. Over time this buildup can cause the injectors spray pattern to change and eventually blocks some of the flow out of the injector.
While these deposits can be removed by our cleaning system, you want to be keenly aware of this issue especially if you have recently switched to E85 to make sure you do not damage your engine as the injector flow decreases. While we have not found a definite cure for this issue, you can try some of this DIY advice with which some of our customers have had success:.
This works when the buildup is only external and is only influencing the spray pattern. By the time the buildup is internal and the flow is inhibited by buildup on the valve seat, this type of cleaning will no longer be effective. Try this at your own risk! We always suggest a professional cleaning like those offered by FIC , but we understand sometimes that is not possible.
Initially the injector will work fine, but without lubricant all mechanical systems with metal to metal moving parts will wear causing irreversible damage to the injector and other fuel system parts. This flow change will reverse if other fuel is once again run through the injector, but of course running fuels that contain MTBE with this injector is not recommended.
Occasionally you may want to verify that your injector is working that the electromagnet is opening the injector valve. This is typically easy to do since the injector makes an audible click when activated. Since the coil wires are designed to be operated with a specific amount of current and the resistance of the tightly wound coil will quickly generate enough heat to melt the wires, we do NOT recommend that you activate your injector with a 12V feed from your car battery.
Instead it is best if you use a low current source, like a 9V battery, which will activate your injector, but without the risk of damage from prolonged heavy current.
Of course this does not mean that everything is perfect, since only a flow and pulse test will determine if the injectors are operating correctly, but you are at least able to tell that the injector valve is not stuck open or closed, which can help you eliminate at least some de-bugging issues. Another simple test you can do at home is to test the resistance across the electrical contacts of the injectors. It is extremely rare to have more than one injector fail, so what you are looking for is one injector that does not match the resistance of the others.
News, products, problems and results. I'm having issues getting my newly build set up to run. So, as you can see the car is near on identical, the only thing not identical is the injectors. The ECU supports both high and low impedance injectors, hence why i didn't think much of using different injectors on the sister car. I loaded his map onto my ECU and the thing starts, however it runs like a dog.
I pulled the plugs and found them to be black and sooty. The real funny thing is my LM-2 wideband says it's running lean, like when i touch the throttle.
If there is a difference, so i add or subtract pulse width at the ECU to get the fueling close? I have the dyno booked in 3 days and i want the thing running and able to drive onto the dyno.
Is there anything i should look for? The motor is totally new, and hasn't had the rings bedded in as yet. I'm simply trying to get it to a running state. With older generation injectors the low impedance design was implemented to help improve response or latency. Ultimately if your ECU is able to correctly control a low impedance injector then there should be minimal difference.
The latency values between the two sets of injectors will almost certainly be different though which needs to be accounted for. What you're explaining doesn't quite add up. Provided the injectors are all clean and flowing evenly I would only expect a relatively small difference between the maps for a high and low impedance injector assuming the actual flow rates do really match.
I would be confirming everything in the mechanical package first - Cam timing, base ignition timing etc. Thanks for the reply. Yes something is not right in the set up. I will double check all the basics, throw a new set of plugs in and then start playing with the tune again. Is there anything alarming about the difference in the "invalid injection time". I'm not too concerned with the slight difference in flow, as that's easily adjusted. I don't know a whole heap about injectors.
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