[Diy_efi] Need help from the experts diagnosing lean state

Marcello A. Belloli mbelloli at speedymotorsports.com
Sun Feb 20 17:22:10 GMT 2005


RG,
     I just got a chance to read this thread.  I agree that looking at the
wavepattern of the electrical side of the injector will not tell you
a lot about the mechanical end of the injector.  But I know what
would.  What about using a map sensor on the fuel pressure regulator.
 You see the pressure pulses from each injector.  Now this isn't
perfect either, but when one or a couple of injectors are acting up
you can easily see them.  We've been using this meathod for a while
at the shop I work.  The injector wavepattern can show you the
opening and closing of the valve in a perfect world, but not usually
in the car.  I took a one day class where they showed us how to see
the opening, closing of an injector with a vertronix scope.  But they
were showing us with a dry inector, and the pattern was easy to see. 
When we went to go do the same thing on the car, it just didn't work
that easy.  We use a fuel tank pressure sensor...I'll find the part
number tomorrow when I go to work, with a simply 7805 regulator. 
This is a map type sensor with a 0-4psi range...not the same as the
one used for measuring engine vaccum.  Just an idea.

Marcello














> Thanks Will, Tobjorn & Brett for your comments and suggestions
>
> I plan to take a look at it again tomorrow or Monday
>
> I'll let you guys know what I see
>
> TNX & Rgds,
>
> RG
> AZ
>
> Bret Levandowski <skishop69 at yahoo.com> wrote:
> My Bad!! I got that backwards. I had to go back and remember. You sould
> see a slight DROP in the current. Wow, shouldn't have gone to work today.
> Too much brain fry. Ski
>
> WSCowell at aol.com wrote: Well, if I'm right, it won't make a difference
> whether you look at voltage or current waveform, because they simply tell
> you about the electrical performance of the winding in the injector.  What
> you really want to know is a purely mechanical thing, i.e. "Is the
> injector lifting off its seat cleanly when pulsed?  What is its spray
> pattern like?  Does it deliver fuel at the correct rate?"   That sort of
> stuff.
>
> What I'm leading up to is that I don't think electrical measurements will
> tell you anything about the important bit inside the injector, the valve
> itself, that lets the fuel through when opened by current flowing through
> the winding.
>
> Regards
>
> Will
>
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