300x Keihin Injectors

[Nick225EFI]

Would anybody be able to answer this please ?

Can the 2002 300x use the keihin white tip injectors, if replaced as a set ?
I understand that the impedance for the keihins is 2 ohms for pink tips and 12 ohms for white tips.

Cheers,

Nick

[Chaz]

Nick,
The white tip injectors are a "saturated" high resistance design that run on low voltage systems like the early pancake fuel box.
The pink tips are "peak and hold" high voltage , low resistance injectors that require a high output driver like the one in a Motorola side mount ECU.
So, to answer your question .. LOL , The Motorola box on the 2002 and up will work with either the white or pink Kehin injector.

[Nick225EFI]

Thanks Chaz, I will stick with the pink ones as its less confusing ! Atleast I know they are the right ones !!!

[Chaz]

[LOSTINJ]

Nick,
The white tip injectors are a "saturated" high resistance design that run on low voltage systems like the early pancake fuel box.
The pink tips are "peak and hold" high voltage , low resistance injectors that require a high output driver like the one in a Motorola side mount ECU.
So, to answer your question .. LOL , The Motorola box on the 2002 and up will work with either the white or pink Kehin injector.

I know this an old thread but I need to clear something up I have 12 ohm injectors now with 1999 twin box ecu , I know switched to 2002 motorola ecu and was informed that a 12 ohm injector will not work on motorola , and was told I needed 2 ohm . Please advise

[Nick225EFI]

It doesn't get any better than Chaz, from what he has said, it looks like both the white tip (That you have) OR pink tip injectors will work on the Motorola 555 ECU. I actually bought spare pink tips, as it was less of an issue.
I hope this helps.
Cheers, Nick

[LOSTINJ]

Thank you !

[Chaz]

The Motorola box on the 2002 and up will work with either the white or pink Keihin injector.

Let me raise my hand to say , I was right and I was also wrong ...

I should have added :

The Motorola has the "ability" to run either injector . Depending which program was loader into it .
If it is a 225 / 250 then it is set up to run the white tip Kehin or Siemens pencil injector .
The same box loaded with the 300x program run's the pink tip only .

I'm down to only a few set's of pinkey's left ...

The Keihen's average around 46 lbs/hr . I haven't used any of these Trick Flow's yet , but they seem as close as a replacement as I can find , short of having custom's built . Trick Flow's parent company is Summit racing so they aren't going broke any time soon , price is right , get two spare's , and for a fully ported big bore motor the few extra lbs/hr would keep the pressure down to the std of 43.5 (3 bar) .

http://www.summitracing.com/search/p...3%2B4294926064

[LOSTINJ]

Now im really confused !! Lets keep it extremely simple I will be running a OEM 300x ecu , will my 12 ohm injectors work ?

[PanRonnie]

Now im really confused !! Lets keep it extremely simple I will be running a OEM 300x ecu , will my 12 ohm injectors work ?

they should
but like they say in the end it,s best to use the intended injectors
but since you probably don,t want to pay 500$ per injector
these are a nice substitute
http://www.fiveomotorsport.com/obd1-...es-450-550-650
best to have an adjustable fuel pressure regulator installed


Injector Compatibility With ECU’s


Fuel injectors are controlled by one of two possible injector control circuits called drivers: saturated (high impedance) and peak-and-hold (low impedance or current regulated).
An injector used in a saturated driver system requires a high resistance value across its coil (12-16 ohms). The high resistance values enable the injectors to operate at low current levels (.8-1 amp) which keep the circuitry cool, promoting longer component life. Unfortunately, because of the low current levels, injector response time is slow, sacrificing dynamic range. Ohm’s law (V=IR) can be used to show the relationship between injector resistance and current level, where V=Voltage, I=Current (amps) and R= Resistance (ohms). A high impedance injector (14 ohms) used in a 12 volt system would require an operating current of 0.86 amps.

I = 12 Volts/14 ohms = 0.86 amps

A peak-and-hold driver circuit utilizes fuel injectors with low resistance coils (2-2.5 ohms) which require more current (4-5 amps) to open (Ohm’s law: I = 12 Volts/2.5 ohms = 4.8 amps). The driver circuitry will overheat if the injector is constantly operated at 4 amps. Therefore, a switching mechanism is built into the circuit which will turn down the current to a lower, more acceptable level after the injector is opened. Once the injector is opened, it takes far less current to keep it open. Thus the term peak-and-hold is used to describe this type of circuitry. After the initial peak of 4 amps is reached, the driver turns down the current to 1 amp which holds the injector open for the duration of the pulse width.
In most peak-and-hold Multi-Port applications, one driver operates two injectors in which case the peak current per injector is 2 amps and the hold current is 0.5 amps. The advantage of this system is the quick response time of the injector. The high initial current instantly creates the magnetic force require to raise the valve. This allows for a wide dynamic range, which is why peak-and-hold systems are used in small displacement, high horsepower engines such as 4 cylinder turbocharged engines.

Figure 1 shows the relationship of current and opening times for high and low impedance fuel injectors.
Figure 1 shows the relationship of current and opening times for high and low impedance fuel injectors.


Figure 1

It is not recommended to use low resistance injectors in a saturated driver circuit.
The additional amperage required to open the injector can overheat the ECU causing permanent damage. In addition, the injector’s opening and closing times may become unstable creating rough engine operation and possible lean misfires.
It is possible, though, to install high resistance injectors in a peak-and-hold system since the amperage needed to open the high resistance injector is lower and within the limits of the peak-and-hold driver circuit.
If you are not sure which injector type will work with which driver circuit, be safe and use the same type that was originally used in the application.

[LOSTINJ]

I have 12 injector for two engines that STR Shaun Torrente built with 300 X intake on 2000 engines . Question is where are my 12 ohm originally used in ? What year and HP engine ?

[PanRonnie]

i think those would be from the mercury 3 liter with the dual ecu,s ( ignition,fuel ) engines
12 ohm if you are reading 1 injector
and 6 ohm if both are good because they are shared on a single wire
12 + 12 = 6 Ohm

[LOSTINJ]

Well spoke to Eric simon today , he said only run the pink 2 ohm injectors.................

Yes I took reading on one injector and yes 12 ohm

[mrcrsr]

12 ohm will not work with the 300x ecu program. it is not the computer that determines it, it is the software installed in the computer.

[LOSTINJ]

Thanks again Charlie !!!