CAI and Underbody wash

[Z-Indy]

Went through an auto-carwash yesterday.

I wanted the option that has the wheel cleaner, but it came with another option. I told the guy I wanted the underbody wash. Don't know why, it isn't winter, but whatever, I didn't want the tire shine or anything. I wasn't thinking about my CAI...

Got done, drove off, started going down the road, everything fine. I stop at a light, and when it turns green and I start to accelerate and get into the boost a bit, the car stutters badly. "WTF?" Then I start thinking "crap. Underbody wash. Probably soaked the CAI. Dumbass."

As long as I stay out of boost, car runs fine. I was a long ways from the house, so I drove to where I was headed and parked it. Came back a few hours later and drove it home. Did the same thing first time I edged into boost a bit. Drove the rest of the way back, staying out of boost. Just before home I tried a bit of boost and it seemed to be fine.

I searched around and can't find much info about CAI's having issues with carwashes except for one thread in an RX8 forum.

Do I need to remove and clean the CAI? Maybe just the hydroshield had water on the outside and wasn't allowing enough air through? Anybody else had a similar issue?

Additional info: I am using a hydro-shield on the filter, and the underbody gaurds are all in place (except for the one piece that has to be removed to install the CAI).

 

[slow 3]

You should be good with the CAI.. If you sucked up water with it then you would have known (your car would not be moving due to hydrolock). If you have that sheild on the filter, then you should be good with some water (since the sheild is to block some water like in a car wash).

 

[Z-Indy]

That's what I figured, but the car wash is the only logical explanation I have for the big hesitation during acceleration...

The thread in the RX8 forum seemed to be the same issue. In that case the guy did the carwash in sub-freezing temps though, and had ice on his filter.

I don't know. I agree that it seems like it shouldn't have been a problem, but SOMETHING was a problem.

 

[JamesCH]

Maybe simply having water in the filter screws things up a little bit. If the pores in the filter are small enough then the surface tension in the water would have essentially sealed up your air filter. After you drove it for a little bit the water evaporated away and freed up the filter again.

IIRC the dry filters used in most CAIs are washed in water, and the water doesn't actually go through the filter, even with soap in the water which generally reduces surface tension.

 

[Z-Indy]

I was wondering if that's what might have been happening. Just not allowing enough air in and essentially choking the engine when it tries to suck air under boost.

 

[Kain]

MAFs are very sensitive. Probably had a few droplets set it off. I would let it dry completely and see if the sputtering still continues. When I wash my car (at home), I don't drive it for a while just in case I splashed the filter when spraying out the wheel wells.

 

[MSMS3]

Yes, let it dry. And I'd pull the filter and set it out in the sun and let it completely dry and put it back on. They can hold quite a bit of water before allowing any of it to get sucked up into the engine. My guess is that it's just a wet filter not allowing you to flow enough air to produce much power.

No check engine light? That is also a sign of just low flow and wet/damp filter that needs to be dried out.

If you get a check engine light get it read and let us know the code number.

 

[Z-Indy]

Update: Car has run fine ever since that day. I think everything is okie dokie.

Now I just need to figure out how to handle it in the future. I like to be able to get the underbody wash, at least in the winter to get the salt coating off, but I don't want to be getting this stuff happening every time. Maybe I can devise some sort of shield I can drop in before the wash, and then take out right after. I don't know. Something for me to think about.

 

[Darth Vader]

The water from underneath gets in via the fender vents so, I just trimmed up a bit of 22 g stainless I had lying around, popped two sets of two holes through the steel and the fender liner and zap-strapped the plate on, behind the vents, covering the vents from splash. All water getting through the vents hits the plate and is deflected downwards, away from the filter.

That said, I wash my car by hand only so, no objective proof it works for this but, even gully-washer rain is held at bay.

 

[JamesCH]

I have never used them personally, but a hydroshield might do the trick.

 

[Z-Indy]

I have a hydroshield on there now. I guess it doesn't work 100% of the time, eh?

May have to do the extra plate on the fender vents thing. Thanks for the suggestion.

 

[MSMS3]

Those fender vents are your source of cold air. You are not blocking them, are you?

 

[JamesCH]

I have a hydroshield on there now. I guess it doesn't work 100% of the time, eh?

That's very disappointing, but good to know.

 

[Kain]

Stop going to your local Scratch-and-Shine and do it by hand.

 

[jeff4880]

My car does the same thing after a under body wash. Just let the filter dry out and it will be all set.

 

[Darth Vader]

Those fender vents are your source of cold air. You are not blocking them, are you?

Well, it's hardly a sealed plenum down there, air's coming in from everywhere, warm and cold. But no, I just hung the plate at the top and let it hang open at the bottom.

 

[Z-Indy]

Stop going to your local Scratch-and-Shine and do it by hand.

A few issues with that:

1) I'm lazy.
2) I don't feel like I can get the underbody as clean and salt free using the garden hose at home.
3) I'd have to use bottled water. I'm on a well, and the water comes out super hard and full of iron if it isn't run through the softener and iron filter (even then it isn't great) and the outside spigots don't use the filtered water.

 

[MSMS3]

Well, it's hardly a sealed plenum down there, air's coming in from everywhere, warm and cold. But no, I just hung the plate at the top and let it hang open at the bottom.

Oh, I misunderstood. It just hangs down loosly from the top like a curtain. Good idea.

 

[Z-Indy]

Haven't had a chance to try Darth's idea yet.

Car was filthy and I was short on time, so I went through a wash again. No underbody wash this time. Still had some issues with the car bucking and kicking like a mule if I crept into boost the slightest bit for the first half hour or so afterwords.

This sucks. Why did I buy a CAI again? (uhm)

Should have gotten an SRI instead. (hand)

 

[JamesCH]

That's weird man, I've been through a dozen carwashes in mine, with the MSCAI, and never had a hiccup (huh)