TonyTwoBags

Googling this turned up several threads on Rennlist & 6speed that cover MAF issues related to throttle drop off after going through a car wash. Where I live there are decent brush-less places that also have power washers for wheel cleaning, etc. My Carrera 2 has an aftermarket intake with two cone filters on either side of the engine bay - a setup that's not as good as the stock unit's moisture control. Eventually I started to notice moisture either tripping the MAF or causing a failure to ignite/misfire immediately after.

Earlier this summer I removed the MAF & intake to investigate. Soapy water was in there, just past the cone filters and in the base of the Y pipe that feeds into the throttle body . After a thorough clean and re-installation I took the car out to ensure the intake had a chance to heat up and the problem didn't resurface.

The next time I went through the wash I put half a dozen small towels around the cone filters to protect from the wash - it worked. No more throttle hiccup. Since then I've done some variation of cloth/shop towels to protect the intake from moisture - no issues or recurrence over the last three months and about 5 washes. I took some pics today and figured this may help add to the thread history on managing moisture with an aftermarket intake.

notes: replaced the missing bracket attachment between the oil cap & the y-pipe. Also replaced the cone filters today

If you guys prefer to turn this into a thread of tassels, master baiting, feel free!

TonyTwoBags

clarification: all the threads I read included troubleshooting coils, plugs, MAF, etc. Seemed to me several prior threads avoided the obvious.

dan_189

That seems like a lot of water, cant be too good for your electrical bits...

TAGPorsche

I guess you don't get major downpours where you live? I'm not a believer in the cone filter especially as it's used as a "cold air intake". I've had similar problems with another car running poorly during heavy rain.

dan_189

It does rain but no major downpours.

My cars not daily driven so if it's raining I generally don't drive it. Personally I don't like driving in the rain that much.

As for the intake, I think it's been shown to reduce hp. Although I don't want to derail this thread.

TonyTwoBags

Intake adds 15whp and the plenum behind it adds 22.63whp so the grey dragon is putting down a bit shy of 290whp. It put up 149.42mph on Saturday near the salt flats. But that's not important right now.

A buddy in Wisconsin has a detail shop and recommended a water sock for the filters - apparently there are quite a few brands. Much of the troubleshooting I've seen for similar symptoms ignores the basic chance that moisture isn't adequately being kept out of the incoming air. Imo all that matters is you take care with whatever mods you go with. I passed on a lwfw because of the risk to the crank so if I wasn't able to keep the intake dry I'd put the stock airbox on.

jhbrennan

While I’m not a big believer in the CAI (where does the cold air come from?) you seem to be pleased with your setup and that’s what matters. Since you’ve identified the problem, why continue subjecting your car to the automated carwash. These cars can drive in the rain without these problems but carwashes spray water at very high pressure and weird angles so I’d suggest no more automated car wash. I don’t use a hose when I wash my car – I use Optimum No-rinse solution and it does an outstanding job.

jgm911t

How does Optimum No-rinse not scratch you paint, can't see how this works? Seems like the dirt particles would build up in your micro-fiber towel and cause scratching. And doesn't it leave dirt on the surface? Just curious.

TonyTwoBags

The detailer buddy is my mentor on car care. He led me out of the sin-filled pasture of brush washing and I'm proud to say the Carrera hasn't been molested by brushes under my watch. Under my right foot, yes, but no swirling will be introduced by me.

Jhbrennan - curious if you have any data you can share on the ills of pressure washing. High pressure is relative to distance from the nozzle. Conversely, when you have your hand on the car and apply pressure through a towel, you are without question rubbing particles against the clear coat.

5CHN3LL

K&N sells the socks that go over the filters that protect this from happening. They are a fine mesh that (apparently) beads/sheds water.

My last aftermarket intake (the K&N one, I believe) came with the filter sock; you can get them from Amazon, Autozone, and many other places.

That would be the first thing I do - someday you're going to forget and ingest enough soapy water to REALLY cause an issue.

If this was happening on MY car, I would do one of two things:
1) Junk the intake (as a public service, there is no way the intake AND the plenum both provided the rated HP upgrades. it doesn't work that way).
2) make a diverter to prevent water from entering the way it's currently entering.

The Bosch MAF we use is both expensive and delicate; getting it wet is going to cost you a new MAF sooner than later.

TonyTwoBags

Thanks - K&N sounds like the ideal option. I'm kidding about the power figures, I don't really think the plenum adds 22.63whp. I genuinely do like the sound, driving dynamic, & look of my engine bay as is. Dataless dyno prognostications aside, the important things are to both enjoy you car and not be a donkey when modifying it. So next steps are likely to buy two filter socks and call it a wrap on this odyssey.

Agreed on the importance of not fouling the MAF &, more importantly, letting moisture get past the throttle body. I know it can torch a motor and am far from blase about that potentiality. That's why I spent the summer testing this approach and reaching out to a friend with relevant knowledge at a professional level. And why I added this thread to potentially help others that don't much care for the stock airbox's quiet and ugly aesthetic. And again - it's not happening today, yesterday or any other day in the last several months of washing and driving.

Long term my plan is to use filter socks and towels during washing, and keep the socks on for regular driving in case a downpour happens. My old librarian Cleo said it's best not to wear socks whilst getting it on, but I think this may be an exception.

jhbrennan

Not sure of the chemistry...but it does work even on black and other dark paints. I use two buckets both with grit guards and never have scratching...but then I don't let my cars get overly dirty.

http://www.optimumcarcare.com/onrwns.php

jhbrennan

My only first hand "bad" experiences with pressure washing is that it puts water where you may not want it - seems like this is your experience also. Also, I've been told by detailers to not use pressure washers on areas protected by film - pressure may be too harsh.

Flat6 Innovations

I see serious MAF issues with all aftermarket intakes.. I have had an engine stall and would not re- start when testing in a heavy downpour... For this I tend to keep intake systems stock.

DBJoe996

Just for consideration - I have a stock air intake box. However, considering my location, Florida, and the torrential rains we get, and having been in the air intake box many times finding leaves and crap in the bottom, as well as a pool of water, I enlarged the drain holes a little bit and drilled a two more for good measure. No more problems with that.