Sudden rough idle & Hesitations after parked overnight!

[Bitsyncmaster]

Whit your latest comments I'm thinking your cap is cracked or has moisture inside.

The spark plug gap sets the spark voltage. With our 0.026" gap I think 20 Kvolts is all you should expect.

It takes 30 Kvolts to jump a 1 cm gap. 1 cm = 0.039"

[Rich]

I agree the onset of the problem (wet, cold, overnight) also lines up with a cracked and/or dirty dist. cap. The condensing moisture can create a permanent or intermittent short circuit from one or more of the 7 high-voltage connections to ground or to any of the other connections.

There is a simple test as a starting point:

A spark "leak" problem at the dist. cap, which can happen with any conventional ignition system like this one, can often be observed in the dark. Arrange yourself and any components so you can see the distributor, then start the engine and just look all around it to see if there are any random sparks flashing across any areas on the exterior of the cap. You shouldn't see any.

This test doesn't prove a cap to be good, only to be bad. There can be sparks "leaking" to ground along the inside of a dirty or cracked cap.

And it is difficult to see any crack in a cap without looking very closely at all surfaces.

[Beachdrifter]

Thank you Dave and Rich.


So the more im reading about caps and rotors, the more im thinking I have to replace mine.

Maybe 17 yrs of corrosion or perhaps cracking is causing wacky stuff with the timing and sparks.

I guess just because one has sparks at the plugs doesn't mean the cap and rotor can't still be bad.
The corrosion or conductivity may be impacted to where current may be delayed to the cylinder causing a retarded spark and thus misfire, which leads to rich mixture, wobbly idle, and popping noises in exhaust. All of which im experiencing.

Will order a service kit and attempt this myself.
Will try to just remove fuel distributer, which I read seems doable for this job without removing air intake manifolds?

Thanks.

[Beachdrifter]

Oh and just to remove the curiosity about possible bad gas, I did drain the tank and refill with newer gas. No change in condition but at least ruled that out.

[louielouie2000]

It’s looking like my car simply had a big vacuum leak. The fat vacuum hose on the back of the warm up regulator was split because a hose clamp dug into it. I’ve driven it a few times since trimming the ends off all the vacuum hoses I could get to and the car is running smoother, quieter, and stronger than she ever has.

Moral of the story: may as well replace any vacuum hoses you can get to while doing your distributor cap!

[Beachdrifter]

It’s looking like my car simply had a big vacuum leak. The fat vacuum hose on the back of the warm up regulator was split because a hose clamp dug into it. I’ve driven it a few times since trimming the ends off all the vacuum hoses I could get to and the car is running smoother, quieter, and stronger than she ever has.

Moral of the story: may as well replace any vacuum hoses you can get to while doing your distributor cap!

Glad to hear it, thanks, I will check out the hoses and things while I'm in there!

[Beachdrifter]

Hi all,

So today I got in there to finally inspect this Cap and Rotor on the ignition distributor.

I removed the air mixture/fuel distributor to access the cap and rotor. Never had removed it before since owning the car. Was not too bad.
4-23-22-CAP-engine1.jpg

Once out of the way, I could see the cap. I popped the cap off and I could see the rotor, below are the pics and the questions I have:

1. The cap with the plugs off. The only thing I saw was a small chip around the center coil plug hole. Otherwise looked fine to me.
4-23-22-CAP1.jpg


2. The cap closer, you can see the chip off the center hole. No cracks otherwise.
4-23-22-CAP2.jpg

3. The inside of the cap, no cracks I see. Looks pretty clean?
4-23-22-CAP3.jpg

4. Closer inside of cap, seeing the contact points and center coil contact. Maybe worn?
4-23-22-CAP4.jpg

5. Finally the rotor. The only thing I noticed was some green light corrosion on the center contact.
4-23-22-ROTOR.jpg

So not sure what all this means, any feedback appreciated.
Since I am in there, I will order a new set of cap, rotor, and plug wires anyways since it's been 17 years since at least any of that stuff has been replaced.
I'll also check the condition of any other hoses in the area, any loose vacuum hoses, etc.

Here are my questions:


1. On the bottom of the fuel distributor , the "pipe of agony"? i think they call it, or also described as the idle air motor tube, is it normal for this tube to be kind of free to the touch and moves around gently? Seems like it is just inserted in there and nothing really holding it super tight. It's held by like a rubber grommet of some sort.

2. I haven't attempted to try to remove the rotor or inside dust cover, I assume what's under the cover should be good. I mean everything else looked clean. What is holding the rotor in place? do I just pull it out by hand? Haven't tried to mess with it yet. I heard you have to mark the position to insert the new one in the same place.

3. Anything else special about the rotor and cap reassembly that I should be worried about?

4. Is that vacuum advance something that I should worry about replacing? And if I do, can it be taken out without actually removing the entire distributor assembly shaft? Meaning is it as easy as just pulling it out and putting a new one in like the cap for example.


I'm praying and hoping that replacing the cap and rotor will fix my hesitation issue and rough idle, misfire, popping exhaust. If not, oh well, i did a good tune up after 17 years, but will be once again puzzled! Just taking it one step at a time.

Thanks all!

[Bitsyncmaster]

Cap and rotor look good in photos but in your first photo looks like some burning probably from the wires running over the cap. Defiantly don't want those wires on the cap. It may be sparking to the wires.

[AugustneverEnds]

How does the plastic shield under the rotor look? In your pic it seems ok but of course I can't see what you can. That was the one that really was the root of my troubles.

You may want to replace the pickup/impulse coil while you have things apart. I know it seems like the "while you're in there" list never ends but that little part can cause bundles of misery.

[Beachdrifter]

How does the plastic shield under the rotor look? In your pic it seems ok but of course I can't see what you can. That was the one that really was the root of my troubles.

You may want to replace the pickup/impulse coil while you have things apart. I know it seems like the "while you're in there" list never ends but that little part can cause bundles of misery.

Thanks, I took a peak under the dust cover as I haven't taken the rotor off yet, and it looks standard and clean from what I can see. When I get the rotor later this week and take it off, I will do a more detailed inspection. But I'm guessing and hoping it all looks ok.