Okay, I found the port to plug in the OBD reader, under the dash, thanks! I went back to the store and got the code reader and here's what it said, I had 7 codes:

1. P0422-Main catalyst below threshold (Bank 1)

2. P1300-Manufacturer control ignition system or misfire

3. P1300-Manufacturer control ignition system or misfire (same as #2)

4. P0136-O2 Sensor circuit malfunction (Bank 1 Sensor 2)

5. P0303-Cylinder 3 misfire detected

6. P1136-Manufacturers control fuel air metering

7. P1250-Manufacturers control fuel air metering (same as #6, but different code #)

So, after reading these codes, I went back in the store and picked up a new coil pack and swapped it out in cylinder #3 (at least I think it was #3 because the coil packs had handwritten #'s on them, #1 in the front, up to #4 towards the back of the car) I fired the car back up and at first it still idled rough and died, then I restarted it and it seemed to run OK. On the 1 mile drive home from the store, the car seemed to run fine again. Then, I pulled in my driveway and when I shifted into park, it died again. I restarted it and it seemed to idle pretty smooth, not perfect, but better than before I replaced the coil pack. Before, it was idling pretty rough, going from about 500 rpm up to about 1250 rpm and back down, over and over and sometimes dying. So, I'm wondering what to do next, if anything an what the other codes mean. Might one of the other codes explain why it still idles a little bit rough and why it died when I parked it? The misfire sure seemed to be gone on the short ride home, it had been running REALLY rough, with the CEL occasionally flashing, on the 1 mile ride home from the store it was real smooth, but like I said when I first started it up, it still idled rough for a bit. I cleared the codes with the code tool and the CEL didn't come back on, but I only drove a mile, so I'm sure it will come back on at some point, considering that it had 7 codes.

Anyway, I'm wondering where to go from here. It drove fine for the short ride home, but then it died when I parked it. I was thinking of replacing spark plug #3, too, not sure what else to do. I'm also wondering about codes #2 and #3, since its the same code 2 different times, why would that be? I should also mention that money is tight for me for the next week or two, I was unemployed for a while and I'm starting a new job next week. So, if I can keep it running OK without doing anything to cause any major damage, without spending a bunch of money right now, that would be a real plus! Once I start getting paid from the new job in a week, I'll be able to put some more $$$ into the car (if I have to!) but hopefully it can wait a bit. Unfortunately, the Audi is my only transportation.

Oh, one more question, I read on other threads about a recall on the coil packs-might this apply to my 99.5 1.8T? Like I said, money is tight for me right now, it would be great if I could take the coil I bought back and get my $50 back and get them replaced for free!

 

Visit your local Audi dealer,give them your vin number and ask if your A4 is included in the coil pack recall.

 

UPDATE! After reading some other threads about codes, etc. I see where its mentioned about old codes being stored and to see what comes back after the codes are cleared. The AutoZone was closing soon, so I figured I'd drive around for a bit and see how it ran and if the CEL came back on. If it came on, I'd go back to AutoZone before they closed and rescan the codes. When I first started it, it idled rough, stumbled and died after a few seconds. Started it again, same thing. Started it again, revved it a little and was able to get going and the car ran real smooth. I drove around for about 20 minutes, got on the highway, etc. and it still ran great and the CEL didn't come back on. Then, when I got home and parked, it died again. I restarted it, it idled a little bit rough, but it didn't die. The CEL still didn't come on. So, I'm wondering if the rough idle might not be related to the misfire problem that now seems to be gone.

I should mention that when I had my wheel bearing replaced about 6 months ago, the mechanic had a VagCom and he cleared my codes for me then, so the 7 codes it had couldn't be more than 6 months old. When he cleared the codes then, the CEL stayed off for a few days and eventually returned. Since then, it would be sometimes on and sometimes it would stay dark when I drove the car.

I'll call the local stealership on Monday and see if they can tell me if my 99.5 1.8T is part of the coil pack recall.

Anyway, if I can get through the next week or so without putting too much money into the car until I start getting paid again, that would be great. I can deal with the somewhat rough idle, although if there's a chance I could still do other damage to the car, I'll have to figure something out. Any ideas about the rough idle or the codes I did have on there?

 

O2 sensor. ideally you should get that fixed if it in fact has that code, cuz ive seen it cause problems. but sometimes and most of the time it just has a rough idle and uses more gas.

the funny thing is the first time i read your posts and replies, i actually was thinking O2 sensor and didn't see that code, but as i look back i obviously did see it and that could/should be your problem.

ive had an old ford probe with a bad O2 for years with no major problems, just a small "self rev" at idle. it can also make your car die at idle. (take this for what its worth, obviously that car was nothing near identical to how these cars run nor are made)

 

UPDATE #2-I did some more searching on this forum and others and it does sound like NHolzschuh might be right, that an O2 sensor could be the culprit for the idling problems. I also drove it some more and had basically the same thing happen, when I first started it, it idled rough, stumbled and died. I restarted it, feathered the gas a bit and was able to get going without it dying and it drove just fine, no misfire anymore from what I can tell, it was as smooth as it has ever been. I drove around for maybe 30 minutes again, got on the highway, etc and the CEL did not return yet. I hit several red lights and it didn't die at all or even stumble. Came back to the house and sure enough, after I shifted it into park-it stumbled and died again!

I searched around about replacing the O2 sensor (or sensors?) Does anyone know of a good diy about replacing them, I haven't found one yet. Also, like I mentioned before, I'm starting a new job this week after being unemployed for a bit, so money is tight for me for another week or so, so I'd like to hold off on replacing the sensor (or sensors) until I'm getting paid again, I HATE to borrow money from family or friends, which I might have to do if I want to fix it sooner. It doesn't sound like driving with a bad O2 sensor for a week or two could cause anything else to go wrong, or could it?

 

it COULD. but i think the worst it may do is mess with your ECU. i.e. put you in limp mode, run more RICH/LEAN, keep your driving minimal and baby the hell out of it for the time being.
no dont granny drive it, 5 under the limit, last one to leave the light, etc., but dont "race-drive" it either. drive safely/nicely not too much stress, and that will buy you some time and keep it running as normal as possible.

also, if you do have "stumbling" at a red light/stop sign etc., keep your foot on the gas to keep the rpm's up to(or close to) 1k. this will keep the flow to your motor, both gas and air, to prevent a stall.

now these few tips im giving you are to be taken with a grain of salt, this is me putting myself in your position(where i have been many times) and to help you on your day-to-days until you can take proper care of your car again. by no means do i condone giving information on not fixing a problem with your car. im simply helping you give yourself as much time as possible to drive your car semi-safely.

also do you still have a CEL on? if you dont have a light i dont think it will be an o2. also replacing your air filter(if at all necessary) this will help slightly with some symptoms.

 

Thanks for the advice, I'm not a lead-foot driver, so babying it until I can fix it shouldn't be a problem, I'm 37, so my days of redlining it on every shift and doing smoky brakestands for kicks are over! Plus, its a bone-stock 150hp 1.8T, so what's the point in flooring it anyways? I'll still get blown away by some 80 year old lady in her Accord V6 who doesn't even know that we're in a race! Luckily, my new job is literally less than a mile from my house, so I won't have to drive much, either.

The CEL hasn't come back on yet, but I only drove the car twice on my two test drives, for about 45 minutes total. I'll try pulling the air filter tomorrow and checking that.

If anyone has any more info on replacing the O2 sensors, that would be great, too. As I mentioned earlier, when I did scan my codes, it said there was a problem with the O2 sensor-it was code #P0136, bank 1 sensor 2, whatever exactly that means.

 

hey i know you want others' input but i found this;
https://www.audiforums.com/forum/b5-models-69/p0136-code-02-sensor-i-doubt-95601/

doing some google searching im finding MAF seems to be coming up.
and that the O2 is reading the mis-communication, not actually the cause of the problem.

anyways ill leave you at that and maybe one of our Guru's can enlighten you more.

 

I'm on my iPod at the moment and can't copy/paste but look at my thread called "car dieing." The thing that happened to me could be the same problem for you. Take a look.

 

that is the post i linked!lol