Can someone refer me to an informative site that might explain the process of this, resistor, saturated vs. non saturated etc etc.

thanks all


Rob

 

anyone? i know its kind of a newbie question but........

Rob

 

 

A fuel injector works like this: fuel pressure keeps fuel in the fuel rail waiting to be let through the injector. A signal is sent to the injector and that operates an electromagnet that opens the plunger that would otherwise stop the fuel. With the valve open, the fuel can flow through to the engine. The amount of fuel that flows is related to the pulse width, longer obviously being more fuel. The pulse width is a product of a base pulse width for the injector times a couple of factors that are determined by the ECU reading from various engine sensors to determine load, throttle position, etc.

Peak and hold injectors are low resistance, normally around 2.5~5 ohms. These injectors respond faster and open quicker because they opening current is higher than the current required to open the injector. So they "peak" up to a value to open the injector and then "hold" slightly less to keep it open during the pulse width. These require lots of current to the injector to peak it open for a large injector and keep it stable, so they are generally not used in high power applications.

Saturated injectors run higher resistance, around 12-16 ohms. This is why people run resistor boxes inline with their peak and hold injectors on OBDII cars, because the ecu is only expecting several ohms. Too much resistance will change the current and can destroy the ecu. I can explain this in greater detail if you want. Anyway, the current is much lower so it is easy to keep it open and stable for a longer period of time (again, reasoning most large injectors are saturated) but it is also much slower to open. This means sudden changes in throttle input may not feel as "responsive" with saturated injectors.

And you didn't think I knew what the combustion chamber was.... hahaha.

Edit: I will edit this to note that large injectors are available in either case. However, very large saturated injectors are generally cheaper to make than peak and hold due to the lower complexity relating to operating. I was not saying that it was impossible to make a high flowing peak and hold injector, I was just saying its easier to open the saturated ones. Most VERY large injectors (850cc+) are peak and hold, but are also very expensive. Sorry for confusion the wording may have caused, I believe the rest of my information is correct.




[Modified by trbob16a, 5:08 AM 6/22/2002]

 

WOW thanks guys i knew how the injector it self worked but not peak and hold and all that.

thanks again guys


Rob

 

errr


hee hee my bad
thanks for being so helpfull

Rob

 

50% of that info is wrong. You have peak & hold and saturated injector characteristics all mixed up.

 

No, actually I dont. Thanks for your input though. Do some searching online.

 

Peak & hold injectors need to be used in conjuction with resistor boxes on Hondas. Most larger injectors are peak & hold.

 

Sure dude, whatever you say.

 

I re-read my post and realized parts of it, about the sizing, were poorly worded. I apologize, I was typing it fast. I have made an edit to the post and noted the poor wording. Sorry for any confusion, and I didn't mean to come across as a jerk to you I was just frustrated from posts in my other thread.

 

so whats right?

 

I believe my post is correct, but I'm tired. If you don't understand the stuff about what is sized what and why then thats my fault for bad wording. The rest of the information about ohm loads and all should be correct.

 

its cool i follow thanks

Rob

 

This should help: http://www.supras.com/~riemer/sonict...rs/RCtech.html it helped me understand alot after reading it good luck!

 

Yeah you should definately read that page. Much better info than turbob16a is offering which is wrong.

I'll take a short time, to explain something simple and prove my point:
You are correct in saying that Peak and Hold injectors offer less resistance compared with Saturated Injectors. But you are absolutely wrong when saying that saturated injectors should be used in conjunction with a resistor box. It is exaclty the opposite. Peak and Hold Injectors offer the least resistance, and therefore have the least voltage drop across the injectors. So they need a resistor box.

And if you'd like I can whip out Ohm's law to prove it.





[Modified by ElectronMan, 7:46 AM 6/23/2002]

 

Kewl, sonic is in calgary! Thats where I live and I've talked to reg many times.....