So I've been dabbling around with the whole O2 simulator concept for replacing the post-cat O2 sensor while the test pipe is in and a wideband O2 sensor takes the post-cat O2 sensor's place. [For off-road use]

The O2 simulator is fabricated, and I'll be using the plug/wires from an old post-cat O2 sensor to hook it up. Also contemplating using power resistors to take the place of the O2 sensor heater for a cleaner installation.

Everything I've read suggests the 555 timer-based O2 simulators work (across multiple brands of cars). If that is so, then great! I could have this stuff swapped in this weekend [for off-road use only]. What I'm really looking forward to, though, is being able to use a wideband O2 sensor for more than 50 miles. Hopefully by placing it in the post-cat position (along with the Innovate Motorsport heatsink bung extender) this goal will be achieved.

 

Jeeze, how time flies! Getting close to my wedding, 12 days away in fact. Still been trying to put some love in my A4 here and there...

Had a test pipe installed for ~2.5 weeks. After that short time the inside is completely black with soot. I'm sure this is due to high EGTs. But I was able to capture AFR information while the wideband sensor was in the post-cat position. It's amazing how much better the sensor performs in that spot compared to right after the turbo!

The O2 simulator seems to work well, but I've got a CEL due to improper heater resistance on Bank 1 sensor 2. Not a big deal, and soon I will replace the current heater circuit resistors with lower resistance resistors to [hopefully] take care of that. If it still doesn't work then I'll hook up an old O2 sensor for its heater circuit only.

Thinking about Plasti-Dip-ing my whole car. In fact, I'd like to strip and prime my trunk lid, fill in the lower line on the trunk line, strip and prime my rear bumper and lower valence, and prime my RS4-style skirts, and then Plasti-Dip my whole car.
BUT: In CA you can't buy pre-thinned Plastidip, unless it's in a spray can. DipYourCar.com is working on a solution for people like me who want to use a spray gun.

 

8 more days until my wedding! Things started to get a little tense last night with my future father-in-law as he was describing his desire that he, his wife, my fiancee, and myself put together a list of tasks and assign each task to somebody to make sure everything gets done in a timely manner. It's a good idea certainly, but I fear it will simply add extra unnecessary stress to the final stages of wedding planning.

Anyways, back to my A4: yesterday my exhaust guy swapped out my ~2.5-year-old Magnaflow 14815 muffler for a Magnaflow 3"in/3"out/centered muffler. Had him install a 3" oval-shaped tip that fits the valence cutout moderately well. Already it sounds a little louder and in my experience mufflers get louder as the break in.
Pics and/or vids are forthcoming

Tonight or tomorrow I may attempt to replace the brushes on my alternator. The voltage gauge in the instrument cluster usually doesn't read @ 14V when driving around, and sometimes it sags a bit. My battery is less than 1 year old.

 

So much for that wedding task list, at least for me LOL. They haven't really given me any tasks I need to take care of right now, and I've got my own stuff under control. Getting married in one week!

Got some time in with my A4 again swapped out the old alternator brushes, that may have been original to the car. See the pic below, the short ones are old and the longer ones are new:


And the slip ring condition, before I cleaned it up (pretty good!):

So far the new brushes seem to help keep the voltage up, but I've only idled it thus far.
To get the alternator out I ended up removing the throttle body. And one thing is for sure: having an electric fan made it a TON easier to get to the alternator!

And just for fun here are pics of my new muffler and tip:




I wish the oval shape was a bit bigger to better fill the valence space but I'm satisfied for now.

Also there was this guy at the muffler shop!

 

It's amazing how time flies. Been married for almost 3 weeks, and so far it's great! Definitely nice that my wife doesn't have to leave at the end of the night (we didn't live together prior to marriage) and when we do things we don't start from two different houses. Therefore my A4 isn't getting quite as many miles added on... though we've been taking my car a lot because my gas mileage is probably ~50% better than her Jeep's (~22 mpg vs ~14).

My A4 has been neglected since we've come back from the honeymoon. I've been working out a lot at the gym, and dinner takes up a decent amount of time every night. I have plans to better integrate all of my tablet-related things behind the tablet, to clean up wiring and whatnot, and also to add in BT voice-over-car-speakers capability. I know how to do it, just have to find the time and motivation to complete the work.

Also kicked around the idea with my wife of getting another A4 to replace my current one. Been looking at a 2001 A4 1.8TQM that popped up in my city (1.8TQM is quite rare in my area), with about 106k miles (mine has 152k miles). Mostly I would look forward to Quattro and Facelift going this route, and my wife has seemed pretty supportive. Not sure how serious I am about it, though, considering the loads of work I've put into my car.

There's also a 1999.5 1.8TQM with 72k miles about 1.5hrs away, but the owner never got back to me. That's probably because my inquiry email started off with me asking about T-belt service, whether it has been smogged recently, etc. Ironically enough both of these A4s are silver, as is mine

EDIT: Checked out the car. It's body is rather clean, considering 106k miles and being 12 years old. During the test drive I realized how enjoyable my current A4 is with how tight everything is (shifter, suspension, etc). I think I may go back tomorrow with my wife, and potentially buy it. Will try to haggle the price down, though, as they are asking $4,350 and there are no maintenance records, the coolant color is suspect, don't know anything about oil changes, there's some potential oil leaks, etc.

 

Bought the 2001 A4 1.8TQM! It's all stock so there's lots of slop in the shifter, the suspension makes it feel like a boat, the (stock) clutch has the soft grab, etc. But it'll be fun

 

Spent most of my day off for Labor Day tearing apart the '98, probably for the last time. Working on getting it back to stock so it could be smogged, and sold.
Got the whole front end off, turbo, oil/coolant lines, intake manifold, and more are also removed.

Had to stop for the day when I got to removing the FrankenTurbo exhaust manifold. I think I have about 8/13 of the nuts removed, but the last 5 or so are a real PITA to access. Will probably have to dremel those nuts off as a couple of them started rounding out when I tried removing them :/

On a happier note, the 2001.5 A4 is running well. Programmed the Homelink visor and that works well. Got my KrautoParts reverse LED bulbs swapped to the 2001 A4, and new windshield wiper blades. Also swapped out the cluster LCD screen, and that didn't quite go 100% but the new screen works most of the time.

 

Removing 12mm wrench-size nuts from a FrankenTurbo manifold absolutely sucks :/ I further cut-down my 12mm combination wrench, and was able to remove 2 more of the nuts, but there are still about 5 left. Two of them have been hit pretty hard with a Dremel, but those nuts still aren't budging yet (and their respective studs will need to be replaced). Gonna tackle them again tonight some more. Wish me luck!

While trying to research better ways to get the FrankenTurbo manifold installed/uninstalled, I learned there are 10mm wrench-size nuts that are intended for use with high-flow 1.8T exhaust manifolds...
https://www.034motorsport.com/hardwa...3dptcfcn5lu9j5
If only I knew about these before... says they're reusable too, which is a must considering the price of a single nut.

 

FINALLY got the FrankenTurbo exhaust manifold off last night. All totaled, I think it took me about 5-6 hours just to remove the nuts holding it in place. Thought I'd share some of the Dremel carnage that was necessary to remove 5 of those nuts:

I'm gonna put anti-seize on the replacement studs, for sure (even though I'll probably never be the person removing them again).

A while back when last removing the fan from the fan clutch (while doing the E-fan conversion) one of the screw heads broke off, leaving part of a screw in the fan clutch. So last night I drilled through that screw and pulled it out with an extractor bit. Easy job.

Also thought I'd put up a pic of the 2001.5 A4 1.8TQM in all its monster-truck and yellowed-headlight-lenses glory:

 

Read through the whole thread again. Lots of great info, thanks for continuing to update it. It's rare to see CA specific info as well, so that's appreciated.

Keep it up.