-----Original Message-----
From: Ken W Stephenson [mailto:kss37215@xxxxxxxx]
Sent: Wednesday, May 11, 2005 7:11 PM
To: dickb@xxxxxxxxx
Subject: 82 Imp
To paraphrase Columbo, there's just one more thing,
Dick. The reason I
got on the computer kick was in one of the few times I got
this thing up
to running temperature, I tried the trick of biasing the
oxygen sensor
lead by touching the battery posts with my left hand while
holding the
terminal. There was no change in the idle. Does
this indicate the CCC
is still in open loop?
Sounds like it. Have you checked the resistance of the EFI
coolant temp sensor? They do fail, it's rare but I've seen a bad one.
If it fails shorted, the CCC stays in the cold engine mode. If it
fails open, (which is much more likely), the CCC goes to the hot engine mode,
so you can check by unplugging the connector when the engine is cold and when
it is warmed up – it should make little difference when the engine is
warm. You can also check the resistance between the two prongs – it
should be somewhere around 900 ohms at room temp, and much higher (1500 ohms or
so) at 180F. Don’t remove the sensor unless you are certain it is
bad AND you have a replacement handy, they often crumble when you try to take
them out! This is the two prong sensor mounted at the top front of the
engine at the upper radiator hose connection, not the switch type mounted under
the AC compressor. Be gentle with this critter, it is brittle and it is
very hard to find a replacement.
Another thought is that it takes a Looooong time to get everything into
normal operation, especially if you have been disconnecting the battery each
time you park it. The memory gets wiped, and it has to go through the
whole "calibration" routine each time you do that.
I assume you are familiar with the calibration routine – if not
study this in your FSM. If you just put the car in normal service, it
will calibrate itself, but you need to drive it for a while to do this.
Otherwise, you can do it in your driveway by following the procedure given in
the FSM.
And, there's just one more thing (right back at you, Detective): The
keep alive wire to the memory is the most vulnerable wire in the harness - it's
the lonesome red #18 wire that dangles out from the 3 wire connector under the
CCC. If this becomes damaged (and it is easy to stress this guy when you remove
the air cleaner assembly to work on those nozzles!), the CCC loses it’s
memory ability, so the car becomes like the Alzheimer’s patient who can
hide his own Easter Eggs – every day is a new day! (This is the
same as disconnecting the battery every time you turn off the engine).
To further explain this, I'm going to strip in here a quote from Bob Harris, a
sometimes IML member who knows more about these cars than anyone else around, I
believe:
For a cold EFI car, provision has
been made for the "warm-up" transition
phase - it is the CCC Memory Module.
Therein lies a fixed program that
provides Idle Speed and Fuel/Air Mix
Ratio and Ignition Timing to maintain
the engine until it can be more
efficiently controlled by the output of the
Oxygen Sensor. Also, during this time,
no vacuum is allowed to either purge
the Vapor Canister nor have fresh
air blown into the rear-most Cat
Converter; the EGR valve, also with
a temp sensor, will not operate. You
will notice a beautifully smooth
drop in "Fast Idle Speed" as the engine
warms. The Coolant Temp Sensor will
warm-up and send a signal to the
computer which will send a signal to
the 70 second Timer which will proceed
to "Time Out." After that
time, the Air/Fuel control, via the CCC, is
handed over to the Oxygen Sensor and
we have Closed Loop Operation. Then the
"Bracketing" may begin,
the Vapor Canister purging begins, the Diverter
Valve now sends air to the rear Cat
Converter instead of the back of the
engine heads, and the EGR Valve
begins to operate, the Air Flow Sensor comes
to life and contributes to the plan
and ignition timing becomes a function
of what is necessary for optimum
operation. We now have ideal conditions of
Fuel Management and emission
requirements.
My comment on the above: I think Bob may have made a small error:
It seems that the air flow sensor comes into operation as soon as the key is
released from the “start” position – that is why the car will
start by stall with the lid off the air cleaner, even when it is ice cold.
I got so many pleas to keep this discussion on the main IML that
I’ll go ahead and post it to the list – when people complain maybe
we’ll have to start a sub group for these cars.
Dick Benjamin
