CIS-E brain damaged?

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

Hey everybody,

I know it's been a long-ass time since I've been active on the list but
I've been occupied with other things (school, mostly).

Anyway, with spring on its way I went out to work on the 16v today and
after coming inside and reading the Bentley for a while I think I may have
stumbled upon a lead to solving my drivability problems.

For at least a year now (probably longer) I've had poor low end power and
an idle that occasionally dips and can't be brought back up with throttle
(it's as if the gas pedal isn't even connected). This is most pronounced
when cold. This winter it has been terrible - I frequently have to sit in
my car and warm it up for 8+ minutes just to be able to get enough power
to back it out of the parking space without frying the clutch. I feel like
I'm abusing my baby every time I drive..

Anyway, one bleak October a few years ago it was raining hard and my
windshield seal was leaking filling my fusebox with water. Eventually I
got that fixed but one of the things that was damaged in the process was
my knock sensor control unit(?) (the one with the vacuum line connection,
whichever that is).

Basically, I know this because it is supposed to send out a (-) signal to
the fuel pump relay when the engine is running and after the water got on
the fusebox it stopped doing this. I carefully checked all wiring and even
checked for the presence of the signal right off the connector for the box
and it was not there. So, desperate for transportation, I wired the fuel
pump relay so that it ran the pumps whenever the ignition was on. Good
enough, I thought.

Maybe not. I noticed a slight reduction in performance at the time but I
(stupidly) didn't make any connection between that and the electrical
trouble. In fact it was so long ago I'm not even sure how dramatic the
difference was. But that winter the car started driving worse and worse
(as it always does now when it gets cold) and I started testing things and
replacing suspicious parts.

So when I was measuring my DPR current today I found that it was
absolutely steady at idle.. 9.95 mA. When actuating the throttle it would
change but at idle it was constant. The O2 sensor is relatively new and
its hooked up. I've double checked practically everything and cleaned
every underhood connector like crazy, so I thought this was a little odd.

To the point -- I read through the whole fuel system chapter tonight in
preparation for a repetition of all the electrical tests tomorrow and
found this paragraph rather interesting:

	If the differential pressure regulator current reads excessively
	high, recheck the installation of the jumper wire at the
	temperature sensor connector. If the current does not increase
	when the full throttle switch is closed, check for a faulty full
	throttle switch or a faulty rpm signal from the ignition control
	unit as described below under Control Unit Inputs.

The current would climb/fall between 16 mA and 20 mA for 20 - 30 seconds
immediately after starting before settling in to an exact 9.95 mA. That
struck me as maybe being 'excessively high'. I didn't try closing the full
throttle switch but I definately will tomorrow. The thing that struck me
though, was that maybe the WHOLE knock sensor control unit is toast ? My
car is running just that bad .. that could very well be the problem!

The bad one (I _think_) is the one with the vacuum input and the yellow
thing on the side. I know its not the tiny one with a 7-pin connector on
it because I've already replaced that (by mistake, I thought I was
replacing the KS control unit). Anybody got one of these things in a parts
car ?

Tomorrow I'm building an LED test light again and going through every
electrical test in order so that I can figure out if this is indeed the
case. Whether or not I get a flashing LED on that rpm signal wire should
tell me if thats the problem. Its my understanding that the DPR reverts to
a limp-home mode when it doesn't have an adequate signal and it seems that
is what it has done but at idle where the mixture is most important it is
so off that it is very noticable. And lately even at 3 grand the car
doesn't pull like it used to.

I've got to fix this! I drove my friend's shit brown Tercel the other
day and I'm embarassed to say that I think it's got more low-end balls
than my car! Help!

-Toby

--
'87 16v