end of my rope

[Livolsi, Stephane]

This is more a lament than anything.  Just throwing all the info out
there, hoping something will stick.
Tell you what, if someone comes up with something I haven't tried yet
and it solves the problem, there'll be a few bucks in it for them.
 
Patient is an 88 5ktqa - beautiful tornado red, cosmetically very nice
and has been running well since I bought it in Aug 2003.
 
A couple weeks ago I started having a 'missing' problem.  Idle was a bit
rough, but the miss was most pronounced under heavy load - for example,
2nd gear, 2500 rpm and accelerating hard.  Also, boost and power are way
down.  When accelerating, the car would accelerate but not as rapidly as
it should, and would periodically surge ahead, then cut back.  The
surging ahead seemed more frequent as I let up on the throttle.  To
rephrase, the car would run better as I reduced throttle.
The car was definitely running rich. spark plugs, exhaust, o2 sensor all
black.  This rich running seems to be fixed, but still have this missing
and cutting out under power.
 
I have an 86 5ktq sedan which is not so nice cosmetically, but ran
really, really well.  I've had it for about 6 years and stayed on top of
maintenance and repairs.  The car ran flawlessly.  It has served as a
donor over the weekend.
 
Here's what we did:
 
Swapped over all coolant sensors and the idle/wot switch and isv.
Swapped the o2 sensor.
Swapped over the spark plugs, coil, distributor, plug wires.
swapped over any suspect vac lines - checked all, and I mean ALL
connections and lines.
Swapped over the fuel distributor, lines, injectors, including the warm
up regulator.
Put in a new fuel filter and air filter.
Checked the fuel delivery and it DELIVERS...  1/2 liter in about 10
seconds.
used the DMM and checked air temp sensor, continuity of the temp sensor
to ecu, coil specs, grounds.....all check out ok.
The cat is not plugged - trust me, it is NOT plugged.
Swapped the ECU from the donor into the good car, then went back to the
original ecu because it didn't make any difference.
(86 donor car has a mac 10, the 88 car has a mac 11c)
 
Swapped over the radiator but that was because we broke the neck on the
old rad.
 
I wrote the above on Sunday night.  Monday morning taking the kids to
school I get a few hundred meters from the house and Knock, Knock,
Knock.  Oh Oh!  This is bad.  Serious knocking in the engine, changes
directly with rpms.  Rod? Bearing?  Regardless of what it is, it's time
for a transplant.  Fortunately I have a very nice MC engine sitting in
the 86 5ktq.
 
Monday I do the transplant, get the donor engine in and took the
opportunity to install the new engine mounts and valve cover gasket that
have been sitting in my basement for a while.  Tuesday, hook everything
up, check, double check, triple check connections.
Fire it up and at first it ran quite poorly with a steady miss.  This
really annoyed me.  Everything in that engine bay came out of the 86
parts car which ran like a top!
We managed to get a good idle after swapping the under dash Idle Volume
Control.  Thanks to SJM's site where he has part numbers for different
cars, we found the one in the car was incorrect, but the donor car had
the right one.  
 
Also, we found that there is a silver metal box in the driver's dash
(screwed to the inside of the lower dash) that has a blue and white wire
cut.  It almost looks like someone did it on purpose, but they sure left
the wires frayed.  putting the 2 ends of the wire together doesn't seem
to improve anything.  Anyone know what this box is and could it be
related to the hesitation under acceleration I am experiencing?
 
So now we have a nice smooth idle, occassional burbling, no black
exhaust.
The problem is still the acceleration and boost.  When I accelerate it
sounds like an air cooled VW, and has the power of one too.  I just
don't get it.  What have we missed?  What was left in the car that could
affect acceleration? 
 
Ecu wiring?
Wastegate frequency valve (this is on the firewall by the coil, right?)?
Oh, I also noticed a purple wire running under the passenger side
carpeting going towards the rear of the car.  The other end is
unattached in the area of the ecu.  Can't see where it would connect to
though.  It definitely does not look like it was factory installed so I
don't think it is a likely suspect.
 
Like I said before, cash for innovative ideas that can cure this.  You
won't retire on it, but I'll make it worth your while.
 
Stephane