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# Fuel Configuration and Testing -> more information about injectors and a more detailed explanaition of the injector scaling

### Tech Articles

Discussion and questions related to the course Practical Standalone Tuning

Where can i find more information on the diffrent type of injectors (Peak and Hold AND Saturated drive)?

How can i tell what type of injector am i dealing with?

Does Injector resistance hase anything to do with its operation type?

How can i measure/find out the 2 parameters needed Peak current and Hold ratio?

connecting an injector to an oscilloscope and actuate the injecotr - will this be the way?

I didn't actually get the part with the base injector pulse width. What is it?

I figured it should have something to do with a ratio between duty cycle for the most amount of fuel needed (@100kPa) and the duty cycle at which the injector is still closed (most duty cycle befor inj. opening). Is this correct?

What is a master pulse width of 10 to 12? do you mean % or ms? Is it the ammount of duty cycle to opening the inj?

This is a hard module and my base knowledge (of the lack of it) isn't helping. :D

Thank you in advance for the clarification.

Tinko_M

First off I recommend watching a few webinars based around your questions(if you already haven't)

This one will cover the table resolution and answer your question about "What is a master pulse width of 10 to 12? "

As for the peak and hold or saturate drive, peak and hold are low resistance injectors, commonly called low impedance (typically under 6ohm) while saturated/ high impedance are typically over 6 ohm.

The peak and hold require either 1 of these 2 things.

A: The ecu needs to be able give an initial "peak" current load to open the injector (typically around 2-4amps) then a "hold" current to hold the injector open (typically around 1/4 of the peak current) although most injector information can be found on the internet.

B: Fitting the appropriate ballast resistor pack with the injectors to limit current draw.

Saturated injectors do not require this sort of set up and are also far more common in the current market.

Thank you Chris for the help.

That first webiner was spot on what I needed to know.

To the topic of low and high Z injectors...

i see alot of evo owners swap from low to high Z and the 2 questions that pop up are

1. how can a stock ecu designt for low Z injectors operate high Z inejctors? does it only need to remove the resistor box or is an operating software/firmware up-date needed

2 why are they moving over to high Z?

i guess it has something to do with the high CC injectors for E85 being available mostly in High Z variant and that's the reason, or are there any other Pro's for the High Z ones?

If you haven't already taken it, I'd suggest our EFI Tuning Fundamentals course as this covers your injector questions in detail (the soon to be launched re shoot goes much further too). https://www.hpacademy.com/courses/efi-tuning-fundamentals/

1. Many of the stock ECUs that run low impedance injectors actually still use a saturated injector drive. The current is controlled with an external ballast resistor box. You can swap to a high impedance injector by removing the ballast resistor and hard wiring the 12V feed to then injectors.

2. The majority of the current crop of injectors that are popular now in the aftermarket are based on the Bosch EV14 injector which is high impedance. That's why we're seeing so many situations where old low impedance injectors are being replaced with modern high impedance offerings.

We usually reply within 12hrs (often sooner)

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