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 gchemist
Senior Chevytalk Moderator
Posts: 20829
Loc: Austin, TX 78748
Reg: 05-09-00
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 12-08-07 05:44 PM - Post#1314075
imapalmark suggested we make an ESC thread. We need boardmembers help to help other 73-87 truck owners.
The following information is provided by swervin ervin.
ESC distributor removal or by pass article:
http://www.73-87.com/7387garage/drivetrain /escrepl...
ESC wiring bypass picture: http://www.73-87.com/7387garage/drivetrain /escrepl...
What is electronic spark control (ESC)?
Electronic Spark Control
An additional electronic control (ESC) is used on vehicles equipped with an LE9 engine. The Electronic Spark Control (ESC) system is a closed loop system that controls engine detonation by modifying the spark advance when detonation occurs. The amount of retard is a function of the degree of detonation.
Controller
The (ESC) controller processes the sensor signal and applies it to the distributor to adjust spark timing. The process is continuous so that the presence of detonation is monitored and controlled. The controller is a hard wired signal processor/amplifier which operates from 6 to 16 volts. The controller has no memory storage.
Sensor
The (ESC) sensor is a piezoelectric device, mounted in the engine block that detects the presence (or absence) and intensity of detonation by the vibration characteristics of the engine. The output is an electrical signal that goes to the controller. A sensor failure would allow no retard.
ESC Vacuum Switch
On LE9 engine equipped vehicles with automatic transmission a "tip in" vacuum switch is used. Its function is to provide a momentary contact closure (signal) to the ESC controller during a throttle "tip in" condition which then briefly retards spark timing to minimize knock. The switch contacts are normally open under steady engine vacuum conditions including no vacuum, and all brief increasing vacuum conditions. Basically the switch closes only during rapidly decreasing vacuum conditions such as that encountered on rapid throttle operation.
We need your help.
Please post symptoms of your ESC failure. Your info can help others.
Thanks!
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS |
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drtyler (4)
