Engine Sputter

Yes, I'm a newbie (sorry).

I bought a 1999.5 Audi A4 1.8T a week ago (155K miles). A couple days ago, I was sitting at a light (in gear, idling), and I felt the engine sputter once. The next day it happened a few more times. Today it happens often (maybe a couple times per minute).

I have not checked trouble codes because the check engine light has not come on. This leads to my first questions:
Will trouble codes be available without the CEL lit?
Can the codes be read at my local auto parts store, or is the VAG reader provide different information (other than being able to clear the codes)?
What does VAG stand for?

After reading through the forums, I was planning to change the spark plugs.
Several references to coil packs were found, but the test requires a code to be listed (reference first question).
If I should be looking elsewhere for answers, I'd appreciate some guidance.

quote:

ORIGINAL: stync

Yes, I'm a newbie (sorry).

I bought a 1999.5 Audi A4 1.8T a week ago (155K miles). A couple days ago, I was sitting at a light (in gear, idling), and I felt the engine sputter once. The next day it happened a few more times. Today it happens often (maybe a couple times per minute).

I have not checked trouble codes because the check engine light has not come on. This leads to my first questions:
Will trouble codes be available without the CEL lit? yup, some dont trigger the light to come on.
Can the codes be read at my local auto parts store, or is the VAG reader provide different information (other than being able to clear the codes)? yeah any autozone can scan it for free.
What does VAG stand for? volkswagen audi group

After reading through the forums, I was planning to change the spark plugs. good place to start
Several references to coil packs were found, but the test requires a code to be listed (reference first question). yeah unless you get a misfire for a certain cylinder, it wouldn't be the coil
If I should be looking elsewhere for answers, I'd appreciate some guidance.

start with the plugs, thats most likely it. while your at autozone pickin up the plugs have them scan the car to see if there are any codes stored in the ecu, then report back

AutoZone connected a scanner which said no codes available.

I changed the spark plugs. The old ones looked OK (definitely not new), and the new ones didn't change the symptom.

The gaskets under the coil packs are dried up and aren't keeping much dirt out, and the end the goes over the spark plug was pretty dusty, but otherwise, they seem OK (can't really tell except that the car runs without CEL lit).

Thanks for the advice so far. Other suggestions?

Try cleaning the MAF sensor, replace the air filter, and change the fuel filter if your over 100k.

what he said. and while your doing that, you might as well seafoam it too

Mixed results...

I cleaned the Mass Air Flow (MAF) sensor and changed the air cleaner (shortly after the suggestion), and I added a can of Sea Foam toe 1/2 tank of gas. No change, and the problem has continued to get worse. Today, I finally got around to changing the fuel filter. No change in symptoms. After a long drive this evening, the check engine light (CEL) finally came on! (YEA!) I'll have it scanned tomorrow and let you know what it is.

Error code says cylinder 2 misfire. I'm going to change the coils tomorrow and see how that works.

Turned out to be the coil for cylinder #2. I would have suspected the coil before all this, except that I expected the check engine light to come on if the coil was bad. Lesson learned. And, I got some likely-needed maintenance out of the way.

Thanks for the help, guys!

Carl