Check the O2 sensor using =
the
same method i.e. at the ECU plug. If the signal wire is shorted to gound it=
would be tell the ECU a lean condition exists. Just replace
the TEMPII sensor if you want to be sure about it. They are cheap and =
fail
often. If no change then you have a spare.
Still have a major rich =
running
problem. My original description of the
problem is attached.
Since that posting, I have tested the Temp II sensor
over its =
entire
operating range and it falls nicely in the curve shown in
Bentley.
Also went through all the other resistance checks shown in Bently
(mostly at the ECU connector plug, which is where I also took my Temp=
II
sensor resistance measurements). Everything is right on the =
money. I
have
triple (at least) checked my connections and grounds. I =
checked
for any
blockage on the fresh air intake. No restrictions.
Revving the egine in
neutral yields thick black smoke. I=
observed that blipping the thottle
quickly but to wide open throttle=
causes the AFM to snap fully open, of
course, momentarily. =
Anybody
ever take notice of this?
I have been told of other cases =
where
all tests of the fuel injection system
are positive and the problem =
being
cured by replacement of the F/I wiring
harness. Has anyone ever=
heard of or experienced this? VERY expensive thing
to replace
without being positive that its the culprit.
Will have the =
exhaust gas
analyzed this week in hope that it will point to
the problem. =
Hopes
for long-planned Memorial Day weekend vacation are slowly
dieing.....=
ORIGINAL MESSAGE
My '84 GL is running very rich.
Mileage is 10 mpg at best. Blows thick
black smoke when =
loaded
(i.e. under acceleration). Down on power in general.
Idle=
speed is eratic but does not stall (yet?). Been driving her daily
under these conditions for months.
Things I've done:
Checked/adjusted ignition timing. Was retarded. Now =
correct
(at least
close). Made no difference.
Measured fuel =
pressure:
36 psi at idle with vacuum connected. 42 psi (at
any =
engine
speed) with vacuum line disconnected. If increase engine speed
=
(with
vac. connected), fuel pressure decreases (yes, DECREASES) to about 32
psi.
Swapped out the air flow meter for another (used but serviceable) one=
.
No
significant change in behavior.
Examined the spark plugs=
.
All four were equally black and sooty.
I also cleaned (with
electrical contact cleaner and, in case of ground
connections, emery=
cloth) and exercised all of the connections I could find
on the =
engine
management wiring harness.
I plan to measure the Temp. II sensor
resistance tomorrow.
An observation: I noticed that the =
position of
the AFM wiper is about 20 or
25% "open" with the engine idling.  =
;This
seemed surprisingly high to me, but
I have no reference. Could =
be
normal. Anyone have any input? I also
adjusted the CO
adjustment screw (under the plug on the AFM housing) and this
had no =
real
effect on the position of the AFM wiper. Had a small effect on
=
the
quality of the idle.
I did a mechanical rebuild on this engine =
two
years ago (did not do anything
to the fuel injection/engine =
management
system). It ran fine and gave me 19+
mpg overall fuel mileage =
until
this problem cropped up a couple months ago.