Stalling While Slowing Down and Wet

[Metallurgist]

I've got an issue where my 4Runner is stalling when I'm slowing down, but only when it's wet. For instance, I can run it through a car wash, and everything works great, idles throughout the wash no problem. Then when I start going down the road and come up to a stoplight, it will bog down and stall. I can restart it immediately without any issue. Today, it was also bogging down while I was driving, but as soon as I let off to start slowing it stalled. Previous owner said that it would do it in the rain, but I hit some heavy rain after the car wash (car wash was only to test to see if my wiring changes helped), and it didn't have the issue :wtf:. I didn't get a video of the dying after the car wash though.

I have replaced major wiring (block grounds, starter cable, chassis ground, added grounds, basically big 3 without adding alt pos). I have replaced spark plug wires (NGK) and coils. I have also replaced the vacuum lines, but I think that's less related.

I haven't decided if it's related or just the exhaust (exhaust was replaced before I bought it), but I am getting a weird sound in a certain RPM range under load. I didn't pay close enough attention to this until testing the dying today, but it sounds like it's grinding even though it's not. I wonder if it's misfiring in a very weird way...Any thoughts here either way would be great!
https://youtu.be/wXar0BTnfrM

 

[Herring Creek]

Not sure if this will help you out any, but my commuter car was a 98 ford escort with a 5-speed. It started doing that same sort of thing you are describing, only it did it all the time for about a week. The timing belt was started to slip and strip out one of the pulleys... she finally broke three weeks ago and that my friend was that.

Only other thing you might could check is your TPS sensor, but if that was bad you should get a CE light.

 

[Metallurgist]

Thanks. I don't have a CE light, and I had them check for codes anyway which there weren't any. I thought about the timing belt, but that doesn't make sense for being moisture related? It was replaced about 20k miles ago before I bought it.

 

[TheDurk]

I would suspect an induction boot leak. Very common on BMWs. Get a spray bottle full of water and spray from the manifold out to the air fliter while revving the engine at 2000 rpm or so. It should stumble if you are near the leak.

Frequently happens when someone doesn't properly tighten the clamp to the manifold or the one to the airbox, and sometimes the rubber just cracks and it is hard to see.

It's worth at least ruling out.

 

[gamefreakgc]

Another thing to check is your IAC valve that's located on the throttle body. It normally will act up and cause it to stall when idleing if it's blocked with debris. Happens more often when the engine is nice and hot.

You can search here on the forums, there's a few write-ups on how to clean it up.

 

[Metallurgist]

Thanks. I cleaned my IAC and TB when I replaced my coils and SP wires. They weren't too bad surprisingly. I was spraying water on my intake last night, but not while revving so I'll have to try that.

My car buddy at work mentioned that my video sounded like the junk in the cat broke loose and is rattling when I hit certain RPMs. My dad (mechanic) said that might make sense because of the water spraying from the bottom messing with the cat and bogging it down. Anyone have experience with a rattling cat?

 

[Metallurgist]

So I wanted to update this thread with what I think I finally figured out. I posted these in the what did you do today thread, but here they are again.

Dirty MAF sensor... One of those things that makes you feel embarrassed to post it.

I cleaned the exposed wire not knowing the others up inside existed, so I took it back apart and cleaned those, too. Then I took it through the car wash, and it didn't die! That was a great feeling.

The true test will be if I can take it through there a few more times and still have nothing happen in case it was a fluke. But judging from past experience, I think I found it.

I think sometime here soon I might just get a whole new unit for a cheap part to make sure everything's at peak working order.

Edit: the rattle on the video was a muffler rattle from a broken baffle. Got that fixed, too with a new muffler.

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