Friday, August 10, 2007

One Removed, Two More On

I removed the first official "mod" I had made on the S4, but added two others. Last fall, my first departure from stock was to replace the OEM dry air filter with a high-flow oiled K&N lifetime filter. The K&N, you see, doesn't have to be replaced. You just periodically remove it, wash it off, add a little oil, and then put it back in. All of the Audi tuners sell these things.

So there I am last week, surfing through Audiworld.com posts and don't I run across someone with a MAF problem. The mass airflow sensor is a delicate little electronic fiddlybit that sits in the airstream just downwind of the air box with the filter in it. The MAF costs something like $300 to replace.

Anyway, this guy posts saying that his MAF is acting up, and the first couple immediate responses are, "Did you put in a K&N filter? The oil from those fouls the MAF sensor."

Oh, goody. As I read it, I could feel the hot rush of adrenaline and paranoia creeping up my neck. I searched the Audi forum for K&N and found many cases of people ruining their MAF sensors by using K&N. Granted, most were probably from them over-oiling the filter, but why take a chance? I immediately ordered an OEM dry filter (which has plenty of flow by the way) and installed it when it arrived two days later. I gently wiped off the screen over the entry to the MAF sensor, and it did indeed have a fine coating of black junk on it. Fortunately, my S4 is the "2001.5" model year which has a Hitachi MAF sensor which seem to be much more robust than the earlier Bosch sensors.

I also swapped in a new cabin filter which I've never done before. Very easy.

Though I removed that first modification, I've added two more. She's now outfitted with a Twin2 cat-back exhaust and a drivetrain stabilizer, both from AWE. The exhaust is high flow with a nice low rumble at low RPMs, and without any harsh notes when you step on the gas. Plus, it's simply gorgeous polished stainless steel. The drivetrain stabilizer was crazy easy to install. You support the transmission with a jack, remove a couple mounting plates, then bolt the bar on. It uses stock bolts on the ends and in the middle bolts right into unused bosses on the stock transmission. The tranny in Audis and VWs is apparently known for being sloppy and this bar makes a big difference. Shifting and response is much more crisp, and the common "clunk" sound between low gear shifts is gone.

All in all, the exhaust plus DTS installation took me six hours, with a good hour and quarter of that spent just getting the car high enough on the jack stands and getting it back down. You can't raise one corner of the car all the way at once, so it's a matter of going up or down a notch or two on the stand, then repeating for each corner over and over until there's enough room to work. Very time consuming and quite a workout hauling the hydraulic jack around and around. It isn't light. The time spent also included lunch and two runs to the hardware store for a couple sockets and a thread tap.

I was pleased with how the underside of the car looked. The rear section of the transmission is rusty, but that's just about it. There were a few tiny spots on some of the suspension members and a couple other support bars, but I'm going to be hitting everything with some Rust Bullet and 3M Rubber Undercoating Spray before winter, so I'm not worried about them.

My next project I believe will be replacing the spider hose which is surely pretty well jammed up with oil by now. See the picture for an easy explanation of why they call it a spider hose. I'll polish and paint the Y-pipe and I'll splice a catch-can into the crankcase breather system to keep oil out of the intake (and turbos and intercoolers). I've been reading my Audi 2.7T engine study guide, browsing projects on Audiworld, and making plans. I used to enjoy upgrading my bike, but I ran out of parts to upgrade. There's way more stuff on a car to learn about and fiddle with. Woo hoo!

1 Comments:

At 2:19 PM, Blogger Adam Reitz said...

Yup, heard about the K&N/MAF issue which is why i never got one.

Yup, definitely more stuff on a car to upgrade (than a bike), but certainly hits the wallet harder... Just got new summer rubber, replaced rotors and pads all around, and installed a rear sway bar on the 18.T. Cha-ching.

Glad to hear you're having fun tweaking the whip!

 

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