Toyota Camry

I own a 1989 Toyota Camry. The car usually runs well except on muggy humid days. I can start the car and after a few minutes of driving, the car will begin to hesitate and it will eventually stop. After that, I have to crank the engine many times before it will start it again and sometimes my battery will drain before I can get the engine to start again. If I do get the engine to start, I will be okay for the rest of the day. This problem’s been going on for a long time now.

I’ve tried several mechanics but they can’t pin point the problem. I was told that most likely it’s an electrical problem.

Does anybody know what the problem may be?

Try replacing the spark plugs, plug wires, and inspect the distributor cap/rotor. Moisture condensation can cause this; especially inside the distributor cap.
As a semi-valid quick test try liberally spraying the distributor cap and plug wires down with WD-40 and see if the problem goes away.
If the problem disappears then you know the fault is in the plugs/wires/cap, etc.

At that age of car, you are about due for a new ignition coil. They go out at 15-17 years or so, at least in my experience with my 80’s era Toyotas.

I think in that model, the coil may be inside the distributor cap. What happens is moisture weakens the coil and it doesn’t have the power it should. It will usually start o.k., but as the steam/moisture builds as the car warms, things go as you describe.

Once the engine dries out, all is fine. When I first came across this, it baffled two independent mechanics, as well as the local Toy dealer. An aftermarket coil is about $40 from NAPA. Fairly easy to swap out. Instructions for testing the coil are in the Chilton’s manual at your local library.

As, another poster has mentioned, it could be something else in the rotor, distributor, etc., but in my experience you are at the “moment for a new coil”
A pix link below

If the car starts well on muggy days then stops after it gets hot then I would think that humidity was not the problem, and that would eleminate moisture. In my experience cars that stop running after they get hot and have no obvious cause usually have an electrical problem. These are hard to diagnose since they will recover and the component that failed won’t show symptoms–until it fails again. A guess would be someting in the distributor. When this happens don’t run the battery down. Just crank a few turns and see if it starts. Wait a while and crank again. Lift the hood to help the engine cool.

It only stops though on humid days, especially if it’s warm out. If it’s not moisture related, the problem should also manifest on dry days, but it doesn’t.

Agreed. And those coil housings can begin to crack and leak over time. They are under the distributor cap.

TiP: the books will tell you to change the entire distributor, but that is not necessary. The coil can be purchased and changed seperately. Doing so may, however, involve removing the distributor, so be sure you get a manual and do this correctly.

After the car starts and is running though, what does the ignition coil have to do with the problem?

How will a new coil keep the car from hesitating and then conking out after the car’s been running for a few minutes?

Interestingly, it has to do with moisture in the coil windings creating shorts, which can either reduce the effectiveness of the windings or short a portion of the windings to ground. If arcing takes place during shorting it also leaves carbon trails, and those can become high resistance paths to ground. If the moisture saturates the carbon trails the resistance drops. The more arcing, the lower the coil performance.

My mechanic tested the voltage on the coil and he said that it’s good. Is there something else he could be overlooking here?

The car probably has an igniter which costs about $350. If somebody knows how to test it, you won’t have to guess.

The Ignition Coil has everything to do with the process of keeping the engine running.

The massive amount of electricity that is needed to fire the spark plugs, which then ignites the fuel mixture in the combustion chamber comes from the ignition coil.

If the ignition coil is shorting out, this means that the amount of electricity that the spark plugs need to ignite the fuel mixture is no longer there, and the engine will not run.

So, if you replace the bad ignition coil with a new one, then the spark plugs will get the electricity they need, in the proper amount, and the engine will keep running.