Hey all...

I was driving on the freeway on my way when an idea crossed my mind, so I thought I'd see what people thought about it. Basically the idea is to have two variable intensity LEDs which measure the voltage going to the injectors. The first LED would measure the primary injectors and the second one the secondary injectors. This way you would know when your secondaries are kicking in (exactly) and hopefully would let you drive in a manner which would minimize fuel consumption. If you wanted to simplify it, you could just have one LED that turned on when the secondaries came on.

Whatcha think?

-ZenFox

 

interesting idea.....although I think a lot of people are going to see the word LED and go "RICER!!!" although I'm a nut for lights...so I say it would be kinda cool...although a lot of people are going to argue since the secondaries are 'supposed' to kick in at 3800

 

When the secondaries come in at 3800rpm, all four injectors fire at half the pulsewidth the primaries had just been firing at. This means the total volume of fuel being injected is excatly the same before and after the transition. So monitoring your secondary injectors won't give you any idea about fuel consumption, only that you've exceeded 3800rpm.

Your basic idea is a good one though. By accessing the ECU's wiring, any of it's outputs could be monitored this way. I'm not sure if you'd get a good solid light from an injector wire though, as they're pulsed on and off very rapidly, and at low duty cycles the average voltage you'd see would be very low, and may not trigger an LED. Simple switched outputs would work fine.

 

Now if you had some way to turn the light on as they reached a certain pulsewidth, that'd be impressive

 

What's an ADC? However, you'd have to experiment to determine the initial voltage that corresponded to the given pulse width. You could then use a simple opamp circuit to raise or lower the voltage to match the minimum 'on' voltage of your LED.

 

maybe as a diagnostic tool--I have seen a fair amount of people on here who have had bogging problems around 3800-4000 on here. If you could just plug and play, you would just need a short drive to find out whether or not your secondaries are firing at all. Would take some guesswork out of it.....since there are multiple causes possible for that problem.

 

uh, my car has this little up-shift light that tells you when you could shift to improve gas guzzling. Mazda at work!