ECM Fault?

[Peter Gargano]

Akselrud, Boris wrote:
> 
> There is nothing, it's a bare stock vehicle with all original parts.

Well, you said...

> Looking at the signal with an oscilloscope is that there is an additional
> abnormal impulse approximately 0.1 .. 0.3 ms wide in between the normal
> impulses opening the injector. This abnormal impulse comes and goes,

It's a simple matter of finding out where this/these pulse(s) comes from. 
It's either generated by the ECM (either faulty ECM or EMR/EMI
getting to a good one), generated by the wiring loom (damage/faulty?),
or (catch all) something else (see below)!

I'd be substituting the ECM, and if that didn't help, I'd look at
the loom. Perhaps running a direct set of test wires to the injectors.
This can't be too hard if it's a TBI unit? 

That's about all I can suggest, other than trying to relate the instant
of "abnormal pulse" to some other vehicle event? Is your alternator
working okay (scoped it recently?). All your earth straps intact/tight/
corrosion free? Nothing lose/scraping so there's a metal-to-metal contact
that's not entirely rigid (exhaust scraping on some wires?)

PG.

PS. (quote of the millennium) "It's gonna be something simple..."