305 Chevy HEI has a 4 lead weather-pak distrubtor connector
unknown
What does this 4 wire weather pak style connector go to?
The 305's in a non-ECM '84 K-10, no O2 sensor, no electronic carb, etc, so
what does the pig tail do to the distributor.
The AIR system melted so I took it off and I'm worried that the truck won't
run right or get bad mileage due to the distributor not working right.
Sean Robinson
Lincoln, NE
Can anyone shed some light? Is it connected to a little computer that looks
at the knock sensor?
small block
It shouldn't start without that connector. The 84-86 had a feedback
setup that was in a open loop. They still used mechanical and vacuum
advance but the pickup relayed ignition information to the fuel
solenoid in the carb.
Small Block
Chevy Mania
none...@execpc.com
In article <6ev9cq$r...@dfw-ixnews5.ix.netcom.com>, "unknown"
<unk...@unknown.com> wrote:
Sean...
You are exactly correct. The vehicle is equiped with ESC (Electronic Spark
Control), basically it modifies the output signal from the distributor
pole piece based upon the signal from the knock sensor. The control for
this in your pick-up is mounted above the glove box (yes it is a little
computer).
GM issued a service bulletin allowing the ESC system to be by-passed, and
doing so is well advised as a failed ESC module will prevent the engine
from starting and the slightest noise picked up by the knock sensor can
kill performance.
The by-pass procedure is to connect the Black and Green wires in the
4-wire connector together, this can be done under the dashboard *AT* the
ESC harness right before it plugs into the ESC module. Then reset the
ignition timing to TDC (zero degrees) or it will ping like a muther!
Now, about that melted AIR system....I take it you refer to the switching
valve off of the air pump....if this is the case, then you need to check
the exhaust system for excessive back pressure as this is almost always
the cause of these parts melting, also check the one way valves to be
certain that they are working correctly.
--
Neil Nelson
If you give a man a fish, you feed him for a day. If you teach a man to fish, he'll probably call in sick a lot in the summer.
Member of i-ATN....international Automotive Technicians Network
summer toys; 70 AAR 'Cuda #s match original not restored
64 Valiant 340 4bbl
winter toys; 95 Dakota SLT 4X4
88 Toyota Camry AWD
Marc
small block wrote in message <351454f5....@news.mindspring.com>...
If I'm not mistaken the system that you are describing (the C3 system) was
used by Chevrolet passenger cars, not the trucks during those years. The C3
system did not have a vacuum advance. The distributor advance was computer
controlled. The mixture control solenoid that you are referring to is
controlled by the computer also, but I don't think that any of the input
that the computer receives to control the carburetor comes from the
distributor. It comes from such things as the O2 sensor, the TPS, the VSS,
the knock sensor (if it had one), etc.
As far as the trucks are concerned, they used an ESC system, which was
basically a standard distributor (with vacuum advance) with a knock sensor
retard added to it. As a matter of fact, the knock sensor was notorious for
creating some problems, and the fix for it was to bypass it. And they did
not use a computer controlled carburetor (C3).
Marc
E. William Lawrence III
Unknown,
The answer to your query is this.
On early 80's model pickups GM used a horrific system known as ESC or Elecronic
Spark Control. This is different than the old ECM controlled EST (timing).
The Distributor has a vacuum advance AND a 4 wire weatherpack connector.
That connector is routed to a small silver box under the dash (above and to the
right of
the brake pedal). That is the ESC controller. It also goes to a vacuum
sensor, knock
sensor and I believe the TCC control for the transmission.
It advances the timing for power and when it sees the pinging from this action
it backs off
a little bit.
The systems are junk, impossible to diagnose as there is little or no service
information,
and in fact GM issued a TSB concerning the disabling of that system. I
unhooked the
one on my wife's truck and it runs alot better now.
If anything disconnection may help your mileage. See if it has been done
already.
The disconnect procedure involves cutting and splicing the green wire to the
black
if I remember correctly.
Bill
ali...@umr.edu