Distributor cap & rotor discussion

1987 Honda Accord 178k

As of the past few days I have noticed that my vehicle isn’t performing quite like it should (stumbling, uneven acceleration, hesitation, slightly rough idling, etc). As far as I know the distributor cap & rotor have never been replaced. I know it should be done anyway, but my question is: will replacing the distributor cap & rotor help or am I most likely dealing with carburetor issues here? Also, is it normal for the distributor cap & rotor to last this many miles and what exactly does it do for your car in terms of engine performance?

Well if your weather is like mine, it just got colder, and it may well be a choke that is not functioning properly. That said, it could be the ignition system. Don’t limit your work to cap and rotor, the wires and plugs are important as well and on a car that old I would see if I could find a capacitor as well.

Caps and rotors last a lot longer then use to before electronic ignition. But 178k and 20 years is pushing it. As joseph said…the cap and rotor is only ONE part of the ignition equation. When was the last time you replaced the plugs???

Plugs and wires and air filter have been replaced in the last 3000 miles. Last week we had an unusually warm and rainy day for November, and then it got cold again overnight literally and thats when I noticed the car behaving weird.

178K miles without replacing the distrib cap and rotor? Man, your living dangerously. Replace those and see if the problem goes away. Damn, these two items are cheaper than the wire set. And just as important. If the problem persists, then consider the carb. Clean the linkages with carb cleaner, and insure the choke is operating freely and properly. One press of the accelerator should close it up before you try to start it.

BTW, the distributor does just that. This car has one coil, and the distributor sends the spark voltage to the appropriate spark plug. It also controls the timing advance and tells the coil when to fire. The plug wire conveys that spark voltage to the plug. It is VERY IMPORTANT to align the new cap to the same orientation of the existing cap, and transfer the wires one at a time to the same location on the new cap to keep the same firing sequence. Otherwise, the car may not start.

Thanks, this car belonged to my uncle. I have only been driving it for about 4 months at this point. I could not find any record of the d&r being changed when going through all the service invoices. If it has been changed, it must have been a long time ago. Also the carb has been overhauled once in the car’s service history so hopefully it is something minor like the choke mechanism or just dirty.

As to engine performance, a good used cap will work as well as a brand new one. Caps and rotors can be visually inspected for any faults.
As long as the tip of the rotor contact is not burned away (slight burning if ok), the cap terminals are not disentegrated, and there is no carbon tracking, the cap and rotor should be fine.
(If you don’t know what carbon tracking is, it is very faint, squiggly lines that may run between several terminals on the inside of the cap. This is caused by OTHER problems such as misfiring cylinders. That carbon track is the spark snaking its way from one terminal to another since it could not go through a faulty spark plug, plug wire, etc.

If there is really nothing obvious wrong with the rotor/cap by looking at it then I think your problem is elsewhere.
Since the vehicle has 178k miles the first thing that should be done (in a shop situation anyway) is run a compression test to weed out any mechanical problem. If the compression is up to par then move on to things like plugs, wires, carburetion, vacuum leaks, etc.

(And if you remove the dist. cap for inspection also try to move the rotor and distributor shaft sideways. There should be no movement. If there is noticeable movement then this means the dist. bushings are worn and this can cause rough running, although this problem usually causes the tachometer needle to twitch or jump around.)
Hope some of that helps.

If the carburetor has been rebuilt, see if the floats were replaced. If they are the black plastic ones,they may be filling with fuel and sinking. If it starts poorly when hot or warm you can suspect the floats. Changing the rotor may help and changing the wires may be great.

This is one of those stupid little questions. Why even ASK??? The cost is MINIMAL…less then $50 for both. Why even bother wasting peoples time with this. Just replace them and see what happens. They are designed to be replaced.


It would be helpful to know if it is a DX or LX (I used to own a DX of this vintage and I’m very familiar with wrenching on it… Changed a clutch, two timing belts, oil pan (thanks Jiffy Lube) Axles, CV boots, water pump.)

Honda used two different types of distributors on this car. An ND and another type- can’t remember the name… Take the distributor and rotor into a reputable parts house and they will get you the correct unit. Check the distributor for slop and oil-- signs of both indicate it has an issue.


If you have a carb, check the IAC/Cold Air system and verify it is working-- on the carb versions they are known to “stick” open and create a cold start rough idle. Check the choke and choke actuation assembly. They should move freely. Avoid “hosing down” the carb with GUMOUT or other harsh carb cleaners since the plastic used does not respond well to these solvents.

Change the plugs and then “read” the plugs after a short drive. If sooty and black, they are indicating a rich mixture and that is due to over-choking or “fuel dump” due to failed carb floats.

Also, check valve lash (yes, you need to do that on this engine). I recall that due to the valve train setup on my Accord DX that the valves would occassionally become too loose or too tight (by a few thousands) causing a very slight roughness on a well tuned engine.

Is it an auto or stick?

Also, check CAREFULLY for vac. leaks-- on this car there is a “black box” with literally 10 lines entering and exiting into the intake circuit. A leak on any one could cause a variety of poor running characteristics-- including failure of the air idle control valves, etc.


Wow thanks for the well thought out and helpful response.

It’s an LX, Standard Transmission. I will have to get a friend of mine to help me with the carb work, i’ve never even touched one. But this sends me in the right direction, thanks.