I have an 86 4runner 22r. The problem usually hapens after it rains or I wash it, but sometimes it does it when there is condensation. It ocassionally does it when it's dry but water definately makes it hapen more often. It will idle rough and low. When I accelerate it stumbles for a while and then runs fine when I floor it or the RPMs go up. I was checking the timing when it was having the problem and the timing is not advancing. Sometimes it's very minor and other times it's really bad. I was thinking it's a short somewhere in the wiring harness. I tested the TPS sensor because I know that that plays a part in the timing, but it works fine. Any suggestions before I start testing the whole wiring harness? I can't see water getting in anywhere.

 

Check to see if there are cracks in your distributor's housing, water getting in that way can cause temporary shorts that will affect performance.

 

Check your distributor and wires. Common issue with old ones. Start up ur yota and go under the hood with a misting spray bottle. Spray it on the ends of your spark plug wires and on/around your distributor cap. When it sputters or dies that's where your issue is.. Process of elimination is your friend

 

So I started spraing everything under the hood with a spray bottle. I sprayed the distributor, wires, sensors, wire harness and couldn't repeat the problem. I eventually took a garden hose to everything under the hood and it continued to run great. Then the next week it rained and the problem came back. I guess I'll start looking under the dash and around the computer.

 

id also say check the cap garden hose prob wont do it as moisture has a weird way of getting into places

 

Might want to spray the O2 sensor wires under the truck.

 

probably just needs a tune up. plugs, wires, cap, rotor.

 

I would go with new distributor and wires for the cost. The problem is that the garden hose trick gets everything wet but doesn't give you the humidity of a rainy day. You may not be able to see crack in the distributor or the wires.

 

My 1994 toyota pickup 22re is doing the same exact thing, the wires to my O2 sensor have been cut, so im thinking that could be it, but im just really not sure. How about let me know what you figure out on your truck bo, it'd be a really big help.

 

The cap, rotor, wires, and plugs are new so that's not the problem. I tested the pick-up and it's fine. I went to look at the computer and noticed that there was moisture under the carpet. I took a hose to the windshield and looked under the glove box and noticed a few drops coming from behind the air box. It looks really difficult to get behind all that stuff to find the leak. My AC doesn't work so it's hard to dry out the interior. I really think that the problem is down by the computer. The problem is that the timming is not advancing, not that it's missing.

 

Sounds like you found it. If the ecu is wet, it's probably toast.

 

But if it is the ECU, then wouldnt the truck not start/work at all? Im having the same issue with mine. Im going to replace the cap, rotor, wires and plugs, since im not sure how old they are.

 

I don't think the ECU is "toast" as that would make the vehicle run badly, if at all, in both dry and wet weather. You need to find the leak around the windshield and I'm guessing it's near the bottom corner. You might have to pull the trim piece and reseal underneath it with something.

Good news is you found the problem, bad news is now you have to find out how to fix it. Is there any rust on the windshield frame?

 

Can you reconnect the wires or are they missing? I'd say reconnect them if you can and see if that helps, might also have to buy a new O2.

 

So I fount this thread:
https://www.yotatech.com/forums/f116...ration-139265/
This is exactly what's hapening.
The other day it was running really bad because it had just rained a bunch here is california. It almost wouldn't idle. I unplugged the tps and the idle went up to normal. The TPS is relatively new but I'll test it anyways. Then I can test continuity from the TPS plug to the ECU plug and hopefully put this problem to rest.