Tampering with the distributors position on the engine will change the timing. So if you are not familiar with how to adjust said timing, DoN'T touch it. You can do SERIOUS damage to the engine. This article requires the removal of the distributor- which is done by removing 3 bolts from the head, and 2 (OBD1) or 1 (OBD2) harness plugs. If you do not know how to re-set the timing, or do not have it marked DO NOT REMOVE OR EVEN TOUCH THE DISTRIBUTOR. You have been warned.
This is written with an OBD-1 distributor as a reference...but it applies to OBD-2 as well, with only a few differences (mainly the harness plug difference).
The distributor on a B-series engine is VERY important. Why? 2 reasons.
1. It controls the ignition.
2. It houses some of the most important sensors that the ECU relies on for normal operation*
*with the exception of TPS, MAP, and temperature sensors.
Here is a schematic of an OBD-2 distributor taken from the Helms manual:
![Image]()
First, lets talk about the sensors- there are 3:
-TDC: Top dead center
-CYP: Cylinder position
-CKP: Crankshaft position
Using these 3 sensors, the ECU can determine very important things: Which cylinder should be firing, when that cylinder is at TDC, and what position or angle the crankshaft is. The B-series distributor uses "hall effect" sensors to determine the position of the engines various components. I'm not exactly sure how they work, but I think the basic idea is when something breaks a magnetic field, it causes voltage to drop. I'm no EE, but here's a better explanation.
There are 2 parts to the sensors- the sensor itself (the black part) and the part on the distributor shaft itself. Here they are in the distributor (with everything else removed):
![Image]()
*NOTE: I do not know 100% for sure that these are labeled correctly, but it makes sense. I've never sat down and taken the time to determine wire colors, etc.
I have not personally seen/heard of one of these sensors going bad, but I'm sure it is possible.
Now on to the more important part of the distributor: the ignition.
The most important part of the system is the coil. It is an induction coil- being that it creates a high voltage from a lower voltage. Here's some further reading. So what happens is the primary coil windings have 12V applied to them. Wound inside of the primary winding is the secondary coil. There is a much larger number of windings- so as to produce the higher voltage. When the 12V is removed from the primary coil, the magnetic field that was formed suddenly collapses, which sends a very high voltage pulse through the secondary coil...and thus we have a spark.
Let's take apart the distributor and take a look. First take the cap off (3 screws) then the rotor (1 screw- it can be a pain!) Next pull out the dust cover. There are 2 wires on the coil (I'll get to that in a minute)- just unscrew them. Be careful not to strip them! They are likely a bit worn from age. Next, remove the 2 larger screws on the top of the coil shown here:
![Image]()
Now you can pull the coil out of the distributor:
![Image]()
Next is the ICM or ignition control module (also called the Ignitor). Think of it like a VERY expensive relay. What it does is control the amount of time that the coil is charged with +12V (this is known as ignition dwell) as well as remove that voltage thus creating the spark. The ICM is also responsible for creating the tachometer signal. This is why it is a very good sign when the tachometer is acting up, it is time to replace the ICM.
The ICM has 4 wires connected to it. They are: +12V, coil control wire, tachometer output, and input from the ECU. The ICM is grounded externally through the body.
![Image]()
To take the ICM out, first remove these 4 wires. It's fairly easy to determine which one goes where due to their respective orientation. Then, there are 2 screws holding it in:
![Image]()
Here's a better picture of the ICM:
![Image]()
Now that our cars are getting older, I am seeing more and more ICMs that are going dead. Some symptoms are:
-Random tachometer jumping
-A completely unresponsive tachometer
-The engine suddenly shutting off while driving- you will be rolling and still in gear...but the tach may or not be responding, and you will have little or no power.
The OEM Honda ignition system is sensitive. While I have seen several ignition modifiers (MSD, Crane, etc) and external coils used with success, I have seen WAY more that cause problems. I have personally seen an external MSD coil kill 2 ICMs on my old car. It has been proven over and over that the OEM ignition system will hold up to VERY large amounts of power. I am in no way saying that these aftermarket products are bad in any way, I am simply saying that the Honda ICM was made to work with the Honda coil, and they work very well in harmony. Don't go buy a hot new igntion box or coil...just replace the parts of your OEM system.
Next lets follow that spark generated by the coil's secondary windings. It comes out of that tower on the front of the coil, travels into the cap, down the front of the cap, out of the cap into the rotor, then out to each of the ignition wires.
![Image]()
Re-installation is exactly the opposite as removal. Just make sure to get the correct wires on the correct terminals. The Coil wires are shaped differently- a circle goes to +12V on the harness, the square is the single wire that goes to the ICM. Also, the ICM wires are a set length so they terminate in a certain position, so it's fairly easy to replace them correctly.
I did not show the rotor or dust cap in this article. The rotor can fail as well. While normal wear and tear is normal to the contact surface, I have seen rotor screws come out, and the rotor to fall off the shaft. This will cause the engine not to run at all, and likely cause some physical damage to the rotor itself, and possibly something else. Take care when installing the rotor on the distributor shaft. You cannot install it incorrectly, BUT, I would recomend using some loctite (blue-medium) on the rotor screw as some added security against failure.
I recomend (as does Honda) that you replace the ignition components at regular intervals. At least do the cap and rotor every year or so (I'm anal).
This is written with an OBD-1 distributor as a reference...but it applies to OBD-2 as well, with only a few differences (mainly the harness plug difference).
The distributor on a B-series engine is VERY important. Why? 2 reasons.
1. It controls the ignition.
2. It houses some of the most important sensors that the ECU relies on for normal operation*
*with the exception of TPS, MAP, and temperature sensors.
Here is a schematic of an OBD-2 distributor taken from the Helms manual:
First, lets talk about the sensors- there are 3:
-TDC: Top dead center
-CYP: Cylinder position
-CKP: Crankshaft position
Using these 3 sensors, the ECU can determine very important things: Which cylinder should be firing, when that cylinder is at TDC, and what position or angle the crankshaft is. The B-series distributor uses "hall effect" sensors to determine the position of the engines various components. I'm not exactly sure how they work, but I think the basic idea is when something breaks a magnetic field, it causes voltage to drop. I'm no EE, but here's a better explanation.
There are 2 parts to the sensors- the sensor itself (the black part) and the part on the distributor shaft itself. Here they are in the distributor (with everything else removed):
*NOTE: I do not know 100% for sure that these are labeled correctly, but it makes sense. I've never sat down and taken the time to determine wire colors, etc.
I have not personally seen/heard of one of these sensors going bad, but I'm sure it is possible.
Now on to the more important part of the distributor: the ignition.
The most important part of the system is the coil. It is an induction coil- being that it creates a high voltage from a lower voltage. Here's some further reading. So what happens is the primary coil windings have 12V applied to them. Wound inside of the primary winding is the secondary coil. There is a much larger number of windings- so as to produce the higher voltage. When the 12V is removed from the primary coil, the magnetic field that was formed suddenly collapses, which sends a very high voltage pulse through the secondary coil...and thus we have a spark.
Let's take apart the distributor and take a look. First take the cap off (3 screws) then the rotor (1 screw- it can be a pain!) Next pull out the dust cover. There are 2 wires on the coil (I'll get to that in a minute)- just unscrew them. Be careful not to strip them! They are likely a bit worn from age. Next, remove the 2 larger screws on the top of the coil shown here:
Now you can pull the coil out of the distributor:
Next is the ICM or ignition control module (also called the Ignitor). Think of it like a VERY expensive relay. What it does is control the amount of time that the coil is charged with +12V (this is known as ignition dwell) as well as remove that voltage thus creating the spark. The ICM is also responsible for creating the tachometer signal. This is why it is a very good sign when the tachometer is acting up, it is time to replace the ICM.
The ICM has 4 wires connected to it. They are: +12V, coil control wire, tachometer output, and input from the ECU. The ICM is grounded externally through the body.
To take the ICM out, first remove these 4 wires. It's fairly easy to determine which one goes where due to their respective orientation. Then, there are 2 screws holding it in:
Here's a better picture of the ICM:
Now that our cars are getting older, I am seeing more and more ICMs that are going dead. Some symptoms are:
-Random tachometer jumping
-A completely unresponsive tachometer
-The engine suddenly shutting off while driving- you will be rolling and still in gear...but the tach may or not be responding, and you will have little or no power.
The OEM Honda ignition system is sensitive. While I have seen several ignition modifiers (MSD, Crane, etc) and external coils used with success, I have seen WAY more that cause problems. I have personally seen an external MSD coil kill 2 ICMs on my old car. It has been proven over and over that the OEM ignition system will hold up to VERY large amounts of power. I am in no way saying that these aftermarket products are bad in any way, I am simply saying that the Honda ICM was made to work with the Honda coil, and they work very well in harmony. Don't go buy a hot new igntion box or coil...just replace the parts of your OEM system.
Next lets follow that spark generated by the coil's secondary windings. It comes out of that tower on the front of the coil, travels into the cap, down the front of the cap, out of the cap into the rotor, then out to each of the ignition wires.
Re-installation is exactly the opposite as removal. Just make sure to get the correct wires on the correct terminals. The Coil wires are shaped differently- a circle goes to +12V on the harness, the square is the single wire that goes to the ICM. Also, the ICM wires are a set length so they terminate in a certain position, so it's fairly easy to replace them correctly.
I did not show the rotor or dust cap in this article. The rotor can fail as well. While normal wear and tear is normal to the contact surface, I have seen rotor screws come out, and the rotor to fall off the shaft. This will cause the engine not to run at all, and likely cause some physical damage to the rotor itself, and possibly something else. Take care when installing the rotor on the distributor shaft. You cannot install it incorrectly, BUT, I would recomend using some loctite (blue-medium) on the rotor screw as some added security against failure.
I recomend (as does Honda) that you replace the ignition components at regular intervals. At least do the cap and rotor every year or so (I'm anal).
