non-fluxuating DPR current (was: CIS-E brain damaged?)

[treed2@u.washington.edu (T. Reed)]

Well, I did all the Bentley electrical tests yesterday and here were my
results:

87 16v Scirocco:

After-start enrichment							OK
	DPR current - measured: started at 158 mA then slowly decreased
		      spec: more than 120 mA for 30 to 60 seconds
Cold-running enrichment							OK
	DPR current - measured: 90 mA
		      spec: 80 to 100 mA
Coolant temperature sensor						OK
	Resistance - measured: 2060 ohms
		     spec: 1500-3000 ohms (68 F - 86 F)
Cold acceleration enrichment						OK
	DPR current - measured: brief 150 mA spike
		      spec: briefly exceed 80 - 100 mA
Air flow sensor plate potentiometer					OK
	Resistance - measured: between 2 and 3 at rest: 4640 ohms
			       between 1 and 2 at rest: 863 ohms
			       between 1 and 2 while lifting:
			        * I skipped this test because I had
				  already put the intake boot back on and
				  I did this test about 6 months ago and
				  it tested out fine
		     spec: between 2 and 3 at rest: greater than 4000 ohms
			   between 1 and 2 at rest: less than 1000 ohms
			   between 1 and 2 while lifting: should steadily
				  increase to approx. 4000 ohms
Full-throttle enrichment						--
	DPR current - measured: * I skipped this test because with the
				  coolant temperature sensor disconnected
				  I was unable to raise the engine speed
				  above idle to the necessary 2500 rpm
		      spec: approx. 16 mA
Deceleration fuel shutoff						--
	DPR current - measured: * I skipped this test because with the
				  coolant temperature sensor bridged I
				  was unable to raise the engine speed
				  above idle to the necessary 3000 rpm
		      spec: briefly change to approx. -45 mA then return
			          to a positive value

CIS-E electrical tests:
	Terminals		Spec		Measured
	=========		====		========
	1 and 2	(ignition on)	12V		12V			OK
	1 and 2	(starter on)	> 8V		10.3V			OK
	2 and 24 (starter on)	> 8V		10.2V			OK
	10 and 12		17-22 ohms	18.7 ohms		OK
	17 and 18 (afp at rest)	> 4000 ohms	4636 ohms		OK
	14 and 17 (afp at rest)	< 1000 ohms	860 ohms		OK
	14 and 17 (afp lifted)	> 4000 ohms	(skipped, see above)	--
	2 and 21		1500-3000 ohms	1600 ohms **		OK
	2 and 8 (o2 wire @ gnd) continuity	continuity		OK
	2 and 8 (o2 wire @ blk)	no continuity	(skipped, see note 1)	--
	2 and 15		continuity	continuity		OK
	2 and 7			continuity	continuity		OK
	2 and 9			continuity	(skipped, see note 2)	--
	2 and 3	(ignition on)	12V		12V			OK
	2 and 4	(ignition on)	12V		12V			OK
	2 and 5 (ign on, WOT)	12V		12V			OK
	2 and 13 (ignition on)	12V		12V			OK
	2 and 25 (starter on)	LED flickers	LED flickers		OK
	2 and 6 (ignition on)	12V		0V			FAIL
	2 and 16 (ignition on)	12V		12V			OK
	2 and 19 (ign + a/c on)	12V		12V			OK
	2 and 20		continuity	continuity		OK

** = the engine had warmed up a bit since the coolant temp
     sensor was last measured so the resistance dropped

Note 1: the test between terminals 2 and 8 was skipped because the test
        conditions reading "green oxygen sensor wire connected to black
        wire" are pretty vague about which black wire to connect to and I
        wasn't sure what they meant.

Note 2: this test was skipped because on trying to test between terminals
	2 and 9 I discovered that there was no terminal 9 (or at least no
	metal crimp inserted in the spot for terminal 9). It looks like
	its been missing from the factory - its function is listed as
	"Ground connection to intake manifold (manual transmission only)"
	but I have a 5 speed and it's a 16v so it has to be a stock 5
	speed (no 16v autos)! Weird, eh?

The test between terminals 2 and 6 that failed was for "Voltage signal
from air conditioning system". While it seems highly unlikely, could this
have anything to do with my problem (ie. compensating for extra load of
a/c compressor when its not there)? My A/C doesn't work (it has lost its
R-12 charge) and when I turn on a/c or defrost with the blower running
when the car is warmed up my idle will rise to 1800 or 2000.


So that's that. My dpr current sits at 9.95 mA and the car refuses to come
off idle when cold. I've replaced my plastic fuel injector inserts and
all 3 o-rings on each injector. I've tested the cold start valve and it
sprays a nice mist of fuel. I replaced the thermo-time switch. Pulling any
one of the four spark plug wires when the engine is running (and cold)
causes the engine to stumble until it is re-installed (ie. all cylinders
are getting spark). The plug wires, distributor, cap, rotor and plugs are
all relatively new. I've pulled apart my coil and cleaned off all the
corrosion I could get to on it. I have a ground wire run from my battery
directly to the coil mounting bracket and from there to the stud at the
back of the intake manifold. My battery terminals are shiny as a mirror.
I've cleaned out the idle stabilizer with carb cleaner and it buzzes
smoothly when the ignition is on (about 3 seconds on, 1 second off, 3
seconds on.. etc). Its resistance checked out last time I measured it. I
have a relatively new fuel filter, air filter and I've replaced all my
vacuum hose with new german cloth-braided rubber hoses.

Which brings me to another question - my air flow sensor plate.

When I checked it 2 days ago, it was smooth as butter. Pinching the center
bolt between my thumb and forefinger I could lift it up and down without
the need for a death grip on the bolt.

Yesterday when I did these electrical tests I tried lifting it just for
kicks. I couldn't get a strong enough hold on the center bolt - it just
slipped out of my fingers without budging. My magnetic tool wouldn't lift
it either.

So I'm thinking something is different between these two circumstances.
I've already cleaned and lubricated the pivot point once (last summer)
because it was excessively 'resistive'. Does the plunger in the fuel
distributor become more difficult to push when the fuel pressure is
different? Maybe that has something to do with it - although I thought
that a constant pressure was maintained there.

It seems to me that given the symptoms (unable to raise engine above
idle.. it seems to stumble a bit if I open the throttle completely) might
point to the air flow plate or something connecting to it binding and
preventing additional fuel from being thrown in to the mix because of the
acceleration. More air might sneak past the edge of the plate at its rest
position because of the wide open throttle butterfly valves but no
additional fuel with it to keep the engine at stoich, thus causing the
slight rpm drop upon stepping on the throttle.

What doesn't make sense is why the problem would usually go away (the
intensity of this symptom goes away at least by 50%) when the car warms
up. There is still a noticable sluggishness off idle - and it seems like
above a certain rpm there is a sudden woosh of power - not an on and off
difference but definately not a smooth curve either.

Also could there be any link between the constant dpr current and a
constant air flow plate? I wouldn't think so.. unless the dpr current was
constant because it was sitting at the relative maximum allowed by the
computer for compensating for the air flow plate.

Thanks for any insight or ideas..

-Toby

--
'87 16v