Bench racing ecms Even if ya hate 101 please read

[garfield at pilgrimhouse.com]

On Wed, 17 Jun 1998 09:04:15 -0400, "Bruce Plecan" <nacelp at bright.net>
wrote:

>>>If I put a resistor instead of the injector will this fool the ECU into
>>>thinking it has an injector present ?.
>>
>>People say yes, some say no, and I'm undecided yet.
>
>Depends on ecm.  For the C3 that your working on, I haven't seen any
>mention of it in the stuff I've seen.  That it would apprear to matter,
>also depends on what you trying to figure out.

Fred, Bruce. Gents.

Guys, this is not some mysterious domain, where like the Japanese (or
was it the Chinese; I forget) in WWII, copied even the DENTS in the
British Sten gun, because they didn't know WHAT was a design feature and
what was not. Heh, funny story that; all the ones they made had exactly
the same dent!

Anywho, Bruce is spot one. IF your ECM has the cicuitry built in to
detect when abnormal current (open or short) levels flow out the INJ
driver, then yeah, you'd need to "fool" it with sumpin. But (and I mean
NO disrespect to GM electrics) this detection feature is only in the
most modern ECM designs, and I'd doubt if the GM ECMs you're dealing
with do this sorta detection. A quick check thru the codes throwable
would tell tho.

If this test IS done by the ECM, then I'd bet multiple brewskis all
you'd need would be a resistor value sufficient to duplicate the hold or
saturation current of the INJ. You DON'T need to duplicate exactly all
the electrical characteristics of an inductor; man, that's imagining a
pretty sophisticated detection circuit in the ECM, for that to be a
requirement. But hey, if you throw codes with no INJs hooked up, even
after tryna fake it with some well-chosen R value, then well yeah man,
hook em up.

Gar