Rough idle / stalling when raining or very humid; hole in distributor?

[AnotherUser]

There seems to be moisture getting into the area above the distributor next to the ignition coil and below the cap and rotor.

I notice there was a hole, as pictured below:

3182

Is this some kind of ventilation hole? I know how important it is to have a tight seal on your rotor cap, but if there is a hole directly below it, it seems to defeat that as moisture get's in there.

[timsrv]

Yes, it's supposed to be there. There's actually 2 of them (the other one is smaller and below where the wires go to the pick-up coil). These are ventilation holes. If/when you get water in your distributor, ventilation is important for getting rid of it. Being that high up on the engine these are pretty sheltered (unlikely to get water inside from here). If you somehow get a liquid inside the distributor these will help it drain out. Tim

[joe myers]

I have this persistent problem that seems to happen when rainy or heavy humidity. The van will start right up and idles fine for awhile but I feel rough patches of idle very soon after. It then will start to stall when I put in in gear or right when I accelerate So i put it in park and rev it a but and it seems fine. . It runs rough like this for a bit (maybe 5 miles) then all is fine all day long without a hitch until the next morning in which this happens again. I thought I fixed this with a new rotor, cap, plugs and wires as well a new fuel filter but I guess not. I haven't replaced the rotor again as I did it just a few months ago. I also checked the rotor and cap and it looks near new.

This one is driving me nuts. Why would it then run all day long perfectly?

any help would be great.

joe

[PNW vanwagon]

i went through same thing when first got my van. rainy wet weather for me would be hard rough start and rough running until engine heated up. i replaced same as you : cap, rotor, spark plugs and plug wires. my problems cleared up right after.

a quick trouble shooting for you: next time its rainy run a hair dryer on the cap for 10 minutes or so. if it starts and runs great - you need to double check the seal on your cap. i used a new OEM gasket and tiny bead of permatex rtv around the edge of the cap to make sure moisture wasn't getting in. if it still runs crappy after the blow dryer - it's something else

[joe myers]

I will give that a shot. I have suspected moisture in the distributor but I replaced the cap and rotor and it went away for a few months. I hadn't touched the the cap since but yet it has come back.

[Flecker]

Another thing that you might consider looking at is the condition of your cables from the battery. If they have started to corrode, that moisture plays a big role integrity wise. Clean up the ends and put some di-electric/ bulb grease on the connections.

[AnotherUser]

Each winter with high winds and storms I am getting moisture blown into the distributor through these holes. Making the car hard to start and damaging the distributor cap.

Is it common for people to block these hole or vent them in a different way?

[timsrv]

If you're having moisture issues inside the distributor I wouldn't blame the drain holes. Humidity inside the cap can be caused by other things. I actually had one once that would do the same thing. Every cold & humid morning I was having trouble starting. When I pulled the cap there was moisture in there. Once I dried it out the van would start & run fine. This went on for a few weeks until it finally dawned on me that during the summer I had blown the top radiator hose and covered the distributor with antifreeze. Blowing that hose actually made the van stall due to all that antifreeze on/in the distributor and around the wires. After replacing the hose I wiped it all down, but some dried antifreeze residue remained.

Fast forward to winter. When it got cold & humid, moisture was attracted to the antifreeze reside and it would bead up on/in the distributor and around the wires (similar to the way salt attracts water). I remedied the problem by removing & thoroughly cleaning the distributor. I also replaced the cap, rotor, and wires. Problem never occurred again

Not sure if that's what's happening with yours, but whatever is wrong, I seriously doubt it has anything to do with those holes. My van has them too and it starts with no issues on the cold & wet mornings. Tim

[PNW vanwagon]

^ had the exact same symptoms as tim. fix was the same: new cap, rotor, spark plugs and wires

also important - the correct distributor cap gasket from toyota

solved all my rough start / running on wet days

[AnotherUser]

If you're having moisture issues inside the distributor I wouldn't blame the drain holes. Humidity inside the cap can be caused by other things.



^ had the exact same symptoms as tim. fix was the same: new cap, rotor, spark plugs and wires

also important - the correct distributor cap gasket from toyota

solved all my rough start / running on wet days

My problems have been after it's been really rainy and windy, rather than from driving in the rain, which makes me think wind is blowing it up into the breather hole.

After I've had these problems, I looked at the distributor cap and it was somewhat melted. This has happened on 2 caps.

I have cleaned off the gasket and it looks good before installing a new cap, so I don't know if it the gasket, although I should probably buy a new one. But if water is getting blown from underneath, it seems like it would go through the breather hole just as easily as a bad gasket.

Here is my melted distributor cap. This might be due to moisture on the rotor, causing it to arch around the plastic

7803

[VanCo]

I've melted multiple caps on my van running MSD ignition. High plug wire resistance is the biggest cause. I ended up running custom plug wires and only Toyota caps.

The vent holes are not your problem. Look for something else.

How are your spark plugs and plug wires?

[timsrv]

I've melted multiple caps on my van running MSD ignition. High plug wire resistance is the biggest cause. I ended up running custom plug wires and only Toyota caps.

The vent holes are not your problem. Look for something else.

How are your spark plugs and plug wires?

Good point, if your plugs are worn out (excessive gaps due to loss of electrode material), that will definitely cause your resistance to go up and it will take more current for the spark to jump the larger gap. FYI, the factory plugs are Denso platinum (60,000 mile plugs). If you got more miles then that or don't know history, then replace them. If they are aftermarket or non-platinum, then I wouldn't trust them at all (regardless of age). I would also recommend only OE Toyota for wires, rotor, and cap. Denso platinum plugs or OE Toyota (same thing) are the only things I would run. Tim

[djshimon]

I've had this problem for a while. Only happens in heavy rain or going through big puddles. From What I see there's 3 holes in the distributor, 2 on the bottom and one down low on the side facing the passenger side.
I've done a few things that haven't fixed problem but helped.
-new wires, rotor, cap
-new cap is "Made in Japan" "YEC"- not sure it's equivalent to Denso?
-Bought new gasket for the cap and the coil.
-Put gasket maker around cap where it meets the distributor(didn't help at all)
-Put a milk jug over dizzy(helped a little)
Nothing really fixed it and runs like crap when I hit a puddle.
Lastly I swapped another dizzy in and seemed to help so far when I poured water over it. I haven't tried it in a downpour.
If the newest solution doesn't work I would consider buying the Denso cap($50!) or was also considering drilling holes in the cap(Since I have a couple) and using a air pump to blow air into the cap/distributor like the 4x4 guys do. Either way cost is similar.

[AnotherUser]

I've had this problem for a while. Only happens in heavy rain or going through big puddles. From What I see there's 3 holes in the distributor, 2 on the bottom and one down low on the side facing the passenger side.
I've done a few things that haven't fixed problem but helped.

Have you tried using a spray bottle to spray water around the engine while it's running to see if there are any exposed wires that are taking in water? Doing this while it's dark, you might see small arcs or your car might hiccup. I tried this and didn't notice anything

[djshimon]

Haven't tried it in the dark. I will though.

[djshimon]

Well today I drove through puddles and a downpour and no problems-I'm going to attribute it to a different cap, but i also swapped distributors and made sure the drain holes were clear in the bottom of the distributor.

[Papay]

I had this experience on another vehicle some years back, not a Toyota. After trying everything you have tried, I finally gave a close look at the coil. The cover of it had fine cracks. Since I had already rubber-spray-coated my distributor cap, I used the stuff on the coil housing too. And that was the ticket.

[Dshimoda]

Hi there,

Drove through a deepish puddle (maybe 8-12” deep) two days ago and within a couple of seconds my 86 Toyota van died and won't start back up. All power seems to be there and it is cranking fine but I don't have spark. When I opened up the distributor there was no visual sign of moisture. Replaced coil cap and plugs a few months ago and replaced wires yesterday. Have checked resistance on wires, power supply to ignition coil, resistance of ignition coil and signal generator and all have checked out. Checked codes and I'm getting a single consistent blink with about 3 seconds in between ( which I think is telling me everything is normal?) I also cleared the codes and have got code #11 a couple of times, but my AC hasn’t worked for a while so I’m wondering if that’s pulling that code. My van has always driven fine in the rain. Previous to this happening I was having a rough start/ idle on second startup when van was warm (don’t know if it’s related but thought it was worth mentioning) Any help is very appreciated!!


Thank you,
Danny

[Flecker]

Hi there,

Drove through a deepish puddle (maybe 8-12” deep) two days ago and within a couple of seconds my 86 Toyota van died and won't start back up. All power seems to be there and it is cranking fine but I don't have spark. When I opened up the distributor there was no visual sign of moisture. Replaced coil cap and plugs a few months ago and replaced wires yesterday. Have checked resistance on wires, power supply to ignition coil, resistance of ignition coil and signal generator and all have checked out. Checked codes and I'm getting a single consistent blink with about 3 seconds in between ( which I think is telling me everything is normal?) I also cleared the codes and have got code #11 a couple of times, but my AC hasn’t worked for a while so I’m wondering if that’s pulling that code. My van has always driven fine in the rain. Previous to this happening I was having a rough start/ idle on second startup when van was warm (don’t know if it’s related but thought it was worth mentioning) Any help is very appreciated!!


Thank you,
Danny


Classic TPS issue. Prolly need to replace it. When my tps went, it also showed a code 11.

Another TIP.... Spend a couple hours and go through EVERY plug you can and put some di-electric grease in them. After 30 years the corrosion can take it's toll. I had a few issues with mine, and like every other unknown history vehicle I acquired (all Toyotas) I took a few days and went through EVERYTHING. Just habit... but I have always had good success greasing the plugs to sort out electrical issues. AND it gives you a moment to find any hap hazard wiring issues, like wire nuts, flakey crimp ons, and on and on... I just went through this with the one I have ripped damn near completely apart and re-assembled. Runs like a top now.

[timsrv]

Hi Danny. I agree that your code 11 is most likely the TPS (Throttle Position Sensor), however, a bad TPS will not prevent the van from running. For that issue I would recommend following the instructions in THIS THREAD (https://www.toyotavantech.com/forum/showthread.php?1242-Article-Cleaning-the-Throttle-Body).

Regarding the no spark/no start issue, if there's no moisture in the cap, then I'd lean towards the puddle episode being a coincidence. Even if it was due to the puddle, it would have dried enough by now to start. Just because the coil is new I wouldn't automatically assume it's okay. IMO it's the most likely thing to fail. When you say it tested fine, how are you testing it? It's been my experience that when testing to the specs in the service manual not even good coils will pass. Not sure why this is, but unless you're seeing open resistance I wouldn't put any merit in a that test (and open resistance would be bad).

If I were experiencing that issue I would probably start by dropping in a spare distributor. If you don't have one, you might consider picking one up as it's a good spare part to keep around. If you need the van right away, then I'd probably purchase an extra coil and swap that part to see if that remedies the issue. If it does then throw away the one in there now. If it doesn't, then save it as a spare part.

Before swapping parts there's a few other things I'd check. These things are outlined in other threads here on the forum. Here's a good one:

http://www.toyotavantech.com/forum/showthread.php?983-new-van-owner-needs-help