Ignition System Radio Noise Condenser
 
Honda ignition systems possess a radio noise condenser. (A "condenser" here is another word for "capacitor.") This condenser is said to reduce interference with the Electronic Control Unit (or Module, a computer which manages the engine's operation), the car radio, and probably the igniter's transistors. For Honda models 1991 and earlier, the radio noise condenser is supposed to be external to the igniter. For all other models, it is built-in to the igniter. Reports at the Honda newsgroups are that replacing an aged condenser on a 1991 or earlier Honda model will improve its performance.
 
Below is a schematic of the ignition circuit for the 1988-91 CRX (among other models). The condenser is near the upper left of this schematic; look for the usual | | symbols for a capacitor.

Note that the capacitor attaches to the + side of the primary winding of the coil.

The drawing below shows the shapes of some of the main components of a typical, older Honda ignition system. This should help you to "put your hands on" your 1991 or older Honda's radio noise condenser. Below it is called by yet another name: "in-line suppressor." Note the suppressor (condenser) attaches via the black/yellow wire to the + side of the ignition coil. Click on the drawing to go to its home site and see further discussion of the igniter.

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A new capacitor may be purchased from www.slhonda.com. It's under "distributor" and listed as a "noise suppressor." Cost is around $6. Autozone or Radio Shack may have these capacitors, too.
 
Below is a photo of a 1991 Honda Civic LX's distributor. Note the black/yellow and blue wires in the vicinity of the coil housing. You want to trace the black/yellow wire to find the external radio noise condenser.
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91 Civic LX Distributor