OK I have an 2000 2.8 A6 w/126,000 miles. Ive had the timing belt and water pump done. Serpentine belt done.Had A CEL forever , indi shop said cats. Dealer said throttle body. replaced throttle body no change. figure I check my spark plugs and walla!! oil all over the end of the plug wires. SO replaced the valve cover gasket and spark plugs. Took it to get the codes read again and they cleared.Hooray CEL gone, car running great, except my dash lights (center cluster) goes out. Whatever no big deal. Go to get it inspected. Somehow the dash lights start working again.afterward. Even better. About 2 weeks later , driving around and it starts sputtering while idling. Gets worse on the way home, whenever I am ecclerating it is missing, and CEL starts blinking, let off the gas and just keep a smooth speed and it stops missing and CEL stops blinking. So I check the codes, I get a p0304 cylinder 4 misfire, and a p0300 random cylinder misfire. After checking on here decide to replace the coil pack and plug wires. Put the new stuff on and it is worse than before. That was a waste of 300.00 apparently. Can any one help me. where should I look next????

 

Did you try putting in new spark plugs?

 

Who did the timing belt. That could be the problem. P0300 is multiple missfire. Also did you change the ignition wire or spark plug wire too?

 

If at low speed the sputter stops I would include fuel pump / fuel filter in the list of items to check, could be a low fuel pressure problem. I wouldn't think coil, plugs or fuel injectors becuase they allfailed at once. You would have to look at something common across air/fuel delivery.

 

Thanks for the advice guys. Some details I think can answer some of your questions.I had the timing belt ,water pump, and serpentine belt done about 30,000 miles ago. so I dont think it is either of those. I also replaced the spark plugs, when I did the valve cover gasket probably 2 weeks before all this happened. When it first started I had been driving it for about 45 minutes. When I pulled into a gas stationed I noticed a low rpm hesitation, and when I parked it started idling rough. I shut it off went in and came out when it started it still idled rough but now it also accelerated rough and the CEL was blinking.Well I had to drive it home and when I was accelerating it was missing but when I got up to speed it stopped. The next day I go out and it seems to be idling fine, when revving it up though Inoticed a backfire.Took it for a spin and missing while accelerating. SOI changed the coil pack and spark pug wires and it started missing while idling.
I dont know what an ignition wire is? I changed the coil packs on the front of the engine, spark plug wires, replaced valve cover gasket, and spark plugs,before this started happening.
SO I am thinking about cleaning my fuel injectors, and changing my fuel filter.
Could some of those small vacuum line around the engine cause this. SOme of them have been replaced, on top the engine in the back around the bank 1 and bank two vacuum valves. There is a small plastic tube that runs next to the fuel rail on the left side that broke, not entirely just about 5 inches of it.but it wasnt hooked to anything to begin with. I think this is the tube the vacuum system uses to draw in/or blow outits air?? not positive though. Could the MAF have anything to do with this problem. Can some one give me a list of things to check and possibly how to check them? I have a bentley CD rom manual but I need to load it on my computer. DOes this manual have testing troubleshooting procedures? Thanks for all your help

 

Try process of elimination...

I would try replacing the coil pack back to the original one and see how the car runs. If it still runs crap, then you know that it is not the coil pack.

What kind of sparkplugs did you get? Did you get the right kind? If you got one of those single prong type, then is your gap correct? Check that.

As for the MAF sensor, take it out and see how your car runs. If it runs better, then it is MAF.

Forthe vacuum leak, spray WD 40 or anykind of flammable aerosol solvent type around the area that you suspect there is a leak. If there is, then your idle will change noticibly.

For now, I wouldn't recommand changing anything else such as fuel filter or cleaning injectors and etc. You need to pin point the issue before going on a ghost chase, which can become expensive very quick. Make sure the repairs that you performed are done correct first.

One thing that concerns me is that you mentioned catalytic convertor code by the indy shop. Did you get to see the code when they told you about it? If your cat is really plugged, then it can cause all those symptoms. But once again, replacing cat is not cheap. One way to check is with a vacuum gauge. Hypothetically, the vacuum gauge is showing about 20 inches at idle. You rev your car to about 1500 rpm, and notice that vacuum actually drops to 12 to 13 inches. (I don't know what the normal operating vacuum of 2.8L is, but you get the point) If it drops, then you probably have a clogged cat. Another option is to tun the car while your oxygen sensor is removed. If it runs a little better, that means that you probably have a clogged cat. Basically oxygen sensor hole is releaving back pressure.

Anyways, good luck on the car.

 

The indie shop showed me the code. That was about a year ago when that happened though. The dealer said it wasnt the cat they tested good, my throttle body needed to be adjusted. 10 mins. after leaving the dealer CEL is back on. Call them up and they say I need a new Throttle body then.Since then done a bunch of stuff, Coils (put old ones back on) plug wires and plugs, andvalve cover gasket. K/N air filter.and everything was good. was just missing the middle lights in the dash.All codes were clear and no lights on. 2 weeks later this happens.

 

K&N filter might be it. It might have coated MAF with oil. Although I currently have one in my car, I have heard mixed results with K&N filters. Some unfortunate souls tend to get heavily oiled filter and oil from the filter messes with MAF. Disconnect MAF wiring and see how the car runs. If it runs better, the it is MAF.then First you can try to clean it with electrical parts clean spray. If not cleanable, then just replace it.

Too bad AUDIs don't have MAPs. My old Honda had MAP and oiled filter was never an issue.

 

I disconnected the MAF last night and no change. Next I am gonna change my plugs again. What are the best ones for this car. There are so many to choose from. I changed them about 2 months ago, about 2 weeks before all this started happening. I bought the middle priced range ones, single tip. I pulled #4 yesterdayu too and it was real sooty, like it is running rich. When I read the codes the frist one to come up was p0304 cylinder 4 misfire and then p0300 multi cylinder misfire. Should I clean my fuel injectors? I did a search on here and someone said they were having similiar issues and took it to the dealer and they cleaned their injectors and everything was fine???

 

Is the car hard to start or does it start right up? When it starts, does it run poorly right off the bat or does it need to warm up first?

Bob