ignition dynamics, and distributor overhaul

as pending a request, i am posting up how to overhaul your distibutor. when it comes to dist's theres not much you can do in the line of an overhaul.. if its shot, its shot. you can adjust the air gaps, but its just kinda delaying the inevitable. what you can do is, take it apart, clean it, check for cracks and fraied wires. and make sure nothing is making contact. fist of here is some basic ignition systems, to help you understand just how everthing works.

the celica dist is of the magnetic pulse generator style, i just got dont ignition dymanics in class this week, so here is some info straight from the power points i studyied from..

Pickup coil (pulse generator)

-A simple and common ignition electronic switching device is the magnetic pulse generator system.
-Most manufacturers use the rotation of the distributor shaft to time the voltage pulses.
-The pulse generator consists of a trigger wheel (reluctor) and a pickup coil.
-The pickup coil consists of an iron core wrapped with fine wire, in a coil at one end and attached to a permanent magnet at the other end.
-The center of the coil is called the pole piece.
-The pickup coil signal triggers the transistor inside the module and is also used by the computer for piston position information and engine speed (RPM).

heres a pic of a typical M.P.G (mag. pulse generator)


to understand it you need to know the basics of how ignition works, im not going to say every step and part. but i will start with how spark is created,

im starting at the coil on th eprimary side. (there is steps before you get to the coil, but im not getting into that)

-The ignition system includes components and wiring necessary to create and distribute a high voltage (up to 40,000 volts or more).
-All ignition systems apply voltage close to battery voltage to the positive side of the ignition coil and pulse the negative side to ground.
-When the coil negative lead is grounded, the primary (low-voltage) circuit of the coil is completed and a magnetic field is created by the coil windings
-When the circuit is opened, the magnetic field collapses and induces a high-voltage spark from the secondary winding of the ignition coil.
-Electronic ignition uses a sensor such as a pickup coil or trigger to signal an electronic module that makes the brakes the primary connection of the ignition coil.

here is a VERY basic coil.


-The center of an ignition coil contains a core of laminated soft iron (thin strips of soft iron).
-This core increases the magnetic strength of the coil.
-Surrounding the laminated core are approximately 20,000 turns of fine wire (approximately 42 gauge).
-These windings are called the secondary coil windings.
-Surrounding the secondary windings are approximately 150 turns of heavy wire (approximately 21 gauge).
-These windings are called the primary coil windings.
-The secondary winding has about 100 times the number of turns of the primary winding, referred to as the turn ratio (approximately 100:1).

Self-Induction

-When current starts to flow into a coil, an opposing current is created in the windings of the coil.
-This opposing current generation is caused by self-induction and is called inductive reactance.
-Inductive reactance is similar to resistance because it opposes any increase in current flow in an coil.
-Therefore, when an ignition coil is first energized, there is a slight delay of approximately 0.01 second before the ignition coil reaches its maximum magnetic field strength.
-The point at which a coil’s maximum magnetic field strength is reached is called saturation

Mutual Induction

-In an ignition coil there are two windings, a primary and a secondary winding.
-When a change occurs in the magnetic field of one coil winding, a change also occurs in the other coil winding.
-Therefore, if the current is stopped from flowing (circuit is opened), the collapsing magnetic field cuts across the turns of the secondary winding and creates a high voltage in the
secondary winding
This generation of an electric current in both coil windings is called mutual induction.
-The collapsing magnetic field also creates a voltage of up to 250 volts in the primary winding

-The ignition components that regulate the current in the coil primary winding by turning it on and off are known collectively as the primary ignition circuit.
-The components necessary to create and distribute the high voltage produced in the secondary windings of the coil are called the secondary ignition circuit

heres a pic of a typical ignition system,


now that the basics are covered, its time to move on to the celica distributor,
here is a basic overview, and actual veiw of your distributor. (this is the gte dist, ohters similar)





thae actual dist (this pretty bitch is my spare lol **note the cracked center terminal. not good, replace the cap if yourss is broken**


engine side

bottom


as i said earlier, you cant realy overhaul these, but heres whats all in it, before taking it apart, here are some tools you will need..
-flat & philips screw driver
-a feeler gauge (in mm's)
- an 8mm wrench.

there are two bolts ont the dist cap, just use the wrench and remove those, thats the wrench's use lol
once you pull the cap, it will look something like this,
the rotor is the red thing, it just pulls off.

with the rotor off note the two pulse generators, one with dust cover removed.


all that holds everthing together is a few screws, you will see them, the two top pulse generators are bolted to a pate, theres two screws holding the plate on, and 4 for the pulse gens. the center shaft has protrusions, the air gap it the distance between those and the pulse generators.

with the top plate off,note the "spur" looking trigger wheel, and pulse generator, (see why i posted the info above)**


and finnally empty,


there is a seal on the shaft, and one between the cap and housing, when overhauling, just make sure they have a light coat of oil, and are not brittle or broke ect. . .

hope this helps team, if it seems confusing, or you have any questions feel free to add my msn and ask away.. im on like forever... so yeah.. lol