5ktq electrical problems update (not fixed)

[Cody Forbes]

> Cody, as far as I know the stock variable reluctance
> crank sensors don't get any voltage.  They actually
> create it, and that's what the ECU reads.  So yea,
> don't freak out if you don't find any voltage down there.
>
> Jim Green

Well my father insisted on me changing the sensors, which I knew would make
no differance and I was right.

His next idea was to get a spare spark plug and look at the spark to see
what was going on. This is with the plug grounded through the engine lifting
bracket on the hydraulic pump mount. Actually seemed like a good idea. On
first startup the spark was ok, right on the verge of purple/blue. I totally
expected that when I turn on the highbeams, a/c etc. it would either go
erratic or go orange. It didn't. Both looking at the spark itself and this
nifty Matco LED spark tester (size of a ballpoint pen, uses inductive
current so you just hold it up to the plug wire) showed no signs of changing
frequency or color. This was done at a variety of engine speeds from 700rpm
idle to 3500rpm which is as high as I like to take my engines with no load
on them, and with a variety of electrical stuff on from everything that I
could find a switch for to just the rad fan. Of course it was 1cyl short,
which in this case should only have exxagerated the problem. Now I know this
isn't the most accurate way to test the ignition at all, but if the ignition
goes weak enough for the engine to stall then it should most likely show
visible signs of either being sporatic or weak (in a colder color). So now
I'm going to wipe the slate of what I thought was wrong and start clean with
just the 100% facts.

1) When my laptop shows 12.8v at the EFI the engine starts missing.
2) When it shows 12.6v the engine will stall unless held above 75% throttle
in which case it holds at 3k rpm.
3) When the battery voltage is 12.7v (fully charged, car off) the charging
voltage is 13.8v, battery @ 12.00v yeilds charging voltage of 13.2v +/-
0.1v.
4) Injector + comes from the ignitioin switch run/start terminal, - through
EFI ECU.
5) EFI ECU is very well grounded.

Now my ideas(even the far fetched ones):
1) My EFI ECU may be done messed up. In the process of building another for
another car, will test tomorrow.
2) Huw may be right that I need the Huwlett Packard (had to do it sorry :-},
never say that again I promise) needs its own fused power supply right of
the ignition switch (draws no more then an amp or two).
3) Spark color may be a rediculous way to check the ignition (though it
seems reasonable and has been a tell tale on other dead cars I kinow of) and
I'm still looking at the same problem.

Likely non-problems:
1) The brand new GM intake air temp sensor and the GM coolant temp sensor
2) Wiring to the above sensors
3) All 3 Mac-11s being dead
4) Engine grounding
5) EFI ECU grounding
6) Ignition switch (brand spankin new)

Things I was asked to check by you guys that I didn't get to do today:
1) Alternator blue feed wire
2) "The famous link" under the dash

I'm going to sleep on it, and test with the new EFI ECU tomorrow. I would
like to take this opertunity to make sure all of you know that I appreciate
ALL of your comments very much. I know it's pretty difficult to nail down
any problem like this when your not in a position to see the car, and
epecially with my total bewilderment on whats going on. I've been working on
cars my entire life and this one is just completely got me and my father
(who is factory Porsche and Audi trained, and ex-Porsche/Audi dealer tech)
stumped. I am wanting to find out what the issue is and why it exists so I
can properly cure it, my father is at the point where he just wants to start
throwing parts at it and eventually something will fix it.

Dan Cordon asked about my business, figured I'd answer that here so nobody
is left guessing. My shop, which is shared by me and my father, is a German
auto repair shop, mostly for Porsche (usually 1 car out of every 50 is
non-Porsche) and we have 4 techs on that side, and also a race shop with
another 4 guys, and also even a restoration shop with 1 dedicated guy. Of
course having a race shop we have our own team too, we race Porsche 914s in
HSR and SCCA mostly. My father started the shop in '79, and I have been
living my entire life there. Actually in recent times I've been known to get
so caught up in doing something to my 5ks that I end up sleeping at the shop
and staying the weekend, so "spending my life there" is turning a bit more
literal then I wish. The shop is called Black Forest Racing (as seen in my
sig) and its in Delray Beach, Florida. Dan asked specifically what I do
there also. Mostly I do the larger and more difficult repair jobs in the
repair shop (like pulling engines and such), and I do everything for the
race team thats needed. Porsches I'll tell you have MUCH more simple
electrical systems then Audi's!

-Cody Forbes
Black Forest Racing
2x '86 5ktq
'87 5ktq
'88 80 4cyl