Ignition System - Hitachi Electronic Honda Prelude II

DESCRIPTION

Note. Some models use Toyo Denso distributors. Refer to IGNITION SYSTEM - TOYO DENSO ELECTRONIC article.

Honda's Hitachi electronic distributors consist of a distributor housing, rotor, and distributor cap. The reluctor, stator, magnets, ignitor and breaker plate assemblies are all located inside the distributor housing.

OPERATION

The reluctor turns with the distributor shaft. It is secured to the distributor rotor shaft by a roll pin. As the reluctor turns, its 4 external teeth come in line with the 2 stator upright teeth.

As the reluctor approaches and passes the stator teeth, variations occur in the magnetic field around them. Each time the reluctor teeth come in line with and then pass the stator teeth, transistors inside the ignitor are turned off and on.

This results in a magnetic field building and collapsing in the primary circuit of the ignition coil. When this field collapses, a voltage surge occurs in the secondary circuit of the ignition coil. When this occurs, a high voltage spark is fed from the coil, through the distributor rotor and cap to the secondary wiring and spark plugs.

Disassembled View of Hitachi Distributor Accord model shown; others are similar. Scheme 1

RELUCTOR-TO-STATOR AIR GAP

Align 2 teeth of reluctor with 2 teeth of stator and check air gap. Check air gap at all teeth as reluctor is rotated. (Scheme 2) There should be equal air gap at all 4 teeth. If necessary, loosen 2 screws securing stator and reposition stator to provide equal air gaps. Tighten 2 screws.

Adjusting Reluctor-To-Stator Air Gap Air gap should be equal at all teeth. Scheme 2

CENTRIFUGAL ADVANCE

Disconnect and plug vacuum hoses at distributor. Connect timing light and start engine. Increase engine speed. The timing mark "T" should appear to move past pointer toward firewall, indicating an increase in ignition advance. If not, check centrifugal advance mechanism for sticking or binding.

IGNITOR

1. Disconnect wire leads from ignitor. Turn ignition on. Check voltage between Blue wire and ground. Also check voltage between Black/Yellow wire and ground. Battery voltage should be present in both instances.
2. Turn ignition off. Set ohmmeter in x100 range. With ignitor leads still disconnected, check continuity between ignitor terminals. (Scheme 3) There should be no continuity with positive probe on Black/Yellow wire terminal. There should be continuity with positive probe on Blue wire terminal.

Ignitor Test. Scheme 3

IGNITION COIL

1. Turn ignition off. Disconnect wiring from ignition coil terminals. Connect an ohmmeter across coil terminals. (Scheme 4) On Accord and Prelude, reading should be 1.06-1.24 ohms.
2. Set ohmmeter in x1000 range. Connect ohmmeter leads to ignition coil positive terminal and coil tower terminal. (Scheme 4)
3. Secondary resistance should be 7400-11,000 ohms. If readings are not within specifications, replace ignition coil.

Ignition Coil Test Some use conventional type coil. Scheme 4

IGNITION WIRES

Carefully remove wires by pulling on rubber boots. DO NOT bend wire or conductor may be broken. Check for corroded terminals, clean if necessary. Connect ohmmeter (on x1000 scale) to each end of ignition wires. Resistance reading should be less than 25,000 ohms. If not, replace wires.

RADIO CONDENSER CAPACITY

Using a condenser tester, check for 0.38-0.56 microfarads.

VACUUM ADVANCE

1. On all models, disconnect and plug vacuum hoses at distributor. Connect timing light and start engine. Make sure idle speed is correct. Connect vacuum pump to advance side of diaphragm (lower fitting) and apply vacuum.
2. Disconnect vacuum pump from diaphragm. Connect a "T" fitting to vacuum pump hose. Connect 2 pieces of vacuum hose to "T" and apply vacuum to both sides of diaphragm. (Scheme 5)
3. Apply 4 in. Hg of vacuum and gradually increase vacuum in increments of 4 in. Hg. To check maximum advance, apply 20" Hg. Ensure that vacuum advance values agree with specification.

Vacuum Advance Test. Scheme 5

DISASSEMBLY

1. Disconnect vacuum hoses from distributor. Disconnect primary wires from ignition coil. Remove distributor cap and spark plug wires. Remove distributor hold-down bolt and remove distributor.
2. Carefully pry upward on reluctor with 2 screwdrivers, cushioned with shop rags to prevent damage to distributor housing. (Scheme 6) Use care not to damage reluctor or stator.
3. Remove vacuum advance diaphragm arm screw. Remove vacuum advance diaphragm mounting screws. Pull out diaphragm. Remove ignitor, stator, and breaker plate assembly. Remove rotor shaft and thrust washer.
4. Slide off pin retainer being careful not to stretch it. Remove roll pin and coupling from distributor shaft. Remove shaft from housing. Remove thrust plate, ball bearing, and oil seal. Inspect and replace parts as necessary.

Removing Reluctor from Shaft Use shop rags and screwdrivers to pry off reluctor. Scheme 6

Scheme 7

1. Install oil seal, bearing, and thrust plate in housing. Lubricate shaft with molybdenum disulfide and install in housing. Install rotor and turn it so that it faces No. 1 cylinder mark on cap. (Scheme 7)
2. Install thrust washer and coupling on shaft. Check that rotor is still pointing toward No. 1 cylinder mark on cap, then align index mark on coupling with index mark on housing. Install roll pin and pin retainer. (Scheme 7): Distributor Shaft Installation
3. Align breaker plate in distributor housing. (Scheme 8) Check that breaker plate moves freely. Be sure diaphragm arm attachment pin does not rotate past end of slot in lower plate.
4. If it does, adjust range of free travel by forcibly rotating plate past its limit in opposite direction. Recheck pin position. Install reluctor with manufacturing code facing up. Install roll pin with its gap away from distributor shaft.
5. Check reluctor-to-stator air gap. Install diaphragm assembly. Crank engine until No. 1 piston is at TDC of compression stroke. Install a new "O" ring on distributor housing.
6. Install distributor, making sure that lugs engage in camshaft groove. Install hold-down bolt. Install distributor cap and spark plug wires. Connect wiring and vacuum hoses. Start engine and adjust ignition timing.

Breaker Plate Installation Be sure diaphragm arm pin does not rotate past end of slot in lower plate. Scheme 8

See also:
• IGNITION SYSTEM - TOYO DENSO ELECTRONIC