It's Impossible 2

[Tuck]

Switching out the fuel pump accomplished exactly zilch.  Same problem as
before - stumbling at high rpm's (starting at, and randomly above 3800 rpm
- which is where the secondary injectors switch on).

Engine temperature and atmospheric conditions have no effect whatsoever
(perhaps slightly worse when cold, but it'll do it on a 100+ degree day).
The secondary fuel injectors all work, and have been swapped out anyway.
The computer works, and has been swapped out anyway, same with the fuel
pump, the crank angle sensor, the leading coil, plug wires, plugs.  The
fuel pressure is correct before and after the filter, the TPS has been
checked, set, and swapped.  The fuel rpessure regulator is getting vacuum.
The MAP sensor and the Mass air flow meter have been swapped out as well -
even though they work.  I even cleaned the contacts on the injectors and
the harness today, just for the hell of it. - to no avail.

For a little bit of story background, I had this problem so badly at the
track at Mid-Ohio that I effectively had a fuel cut at 3800 RPM (on a
borrowed set of injectors) - although occasionally it ran well enough that
I could get over the hump and get jerkily up to 6 grand or so.  I tried
disconnecting the map sensor (thinking that maybe the porting on the engine
was confusing it) and it seemed a little better, but it turned out to just
be flukey - it went right back to doing it.  I borrowed a map sensor with
no results.  About halfway through Ohio on my way back to VA the car
magically fixed itself and ran great the whole way home (minor flat spot at
3800 on occasion - but that was typical on 86-88 RX-7's when they were
new).  I stopped at the shop I had borrowed the injectors from and put mine
back in, drove the car a block away and the body shop had it for four
months for a complete makeover and repaint.  Got it back last friday,
realized that I had forgotted to plug the harness back into the secondary
injectors (duh), but the problem remained after I plugged them in.

Any suggestions?


Justin"Tuck" Cordesman
SOLID BRASS-> Dancing with the devil in the pale moonlight.

Lux in tenebris lucet et tenebrae eam non comprehenderunt.
The Light Shines in the Darkness and the Darkness does not see it.