Sorry for the long post guys, but I'm really frustrated with this car. I wish I knew about the cylinder misfire problem this engine seems to be prone to. But anyway, here's the story.

Got a 2003 A4 quattro 3.0 6spd with about 190000km on board. The car was clean inside and out and seemed to run well when I tested it at the dealer, but didn't step on it really hard. Well, on the first day I took deliver on the hwy, the engine was warmed up nicely and I gave it a few good 5-6000 rpm, when, all of a sudden the CEL started blinking and the car seemed to shudder a bit. I took it easy and in a few seconds the CEL stopped blinking. The next day when I started the car the CEL was on and not blinking. I happened to have an obd2 reader and hooked it up. The code was P0304, cylinder 4 misfire detected. Went online and read everything I could find about cylinder misfire and possible causes. The next day I got the misfire problem again when accelerating hard, but this time the code was P0300, P0301, and P0306. So random misfire, cylinder 1 and 6. After some more reading I did the following:

* replaced all spark plugs with new copper plugs
* replaced the air filter with original audi
* cleaned the mass air flow sensor with electrical contact cleaner and 99% isopropil alcohol, and dried it well
* there is a hard plastic hose coming out of the air filter case towards the front of the car and then going down and disappearing somewhere beneath the radiator. That hose was broken and someone had put electrical insulating tape around it as a fix. I've replaced the electrical tape with stronger duct tape until I can get this hose.
* did one tank of seafoam in gas (hoping to clean the injectors if dirty) and put one can of seafoam spray through the engine

Then I did a lot of hard accelerating when entering the hwy, and it felt like a different car. The acceleration is smooth, the gas consumption has dropped, and no misfires happened when I accelerated hard. I was so happy... until this morning. Started the car and the darn CEL light was on again. Checked the code and this time it was only cylinder 4 that misfired. Checked the frame freeze (other parameters that were recorded when the cylinder misfire was detected) and it looks like the attached image.

Oh yeah, I checked with the dealer and all ignition coils were replaced in Aug. 2010 under the recall program.

Any ideas where I should go from here?

 

on my 01 jetta 1.8T i usually had misfires as per vag-com, car ran well 30MPG, 285TQ-265HP, traded in at 199xxx still running well and put check lite on but i just drove it, never let me set fot that reason, vag-com is the best diagnostic for vag cars

 

Having the same issue. Did you ever figure out what your problem was?

 

buy a cheap Vagcom cable and try to meassure blocks to see misfires in real time.

 

Just to clear this up. You cannot read each cylinder with a knock off version of vagcom. You need the true version. If u have a flashing cell it very well could be your coilpack going out. Even though yes i understand they replaced them already there is a chance that it could still take a poop on you. I would recommend if its only flashing on cylinder misfire u swap out that coil to an other cylinder and see if the code follows it. If so your coil is bad. Best place for a single coil is autozone or advance. something along the lines of 18 dollars.

 

A bad coil pack seems a logical answer. I will try locating the bad one and moving it.

 

This is why you do NOT buy a 3.0....


Cylinder 4 and cylinder 5 become porous and coolant seeps into the cylinders causing misfires.

 

If coolant is leaking into my cylinder, would this be an intermittent problem? Wouldn't the spark plugs have some different discoloration on them? This is the first time of hearing a problem with the 3.0L. Besides the occasional misfire, it has been a very reliable engine.

 

i don't have problems with any cylinder from that Bank.

 

My 3.0 hasn't had any misfires lately. And yes, for about a month and a half I've been running only 87 octane (regular) gas. I've kept track of the mileage and I see no significant difference in the distance per dollar. The only difference I've noticed is that hard acceleration isn't so peppy. But then again, most of the time I don't step on it too hard. My loud custom exhaust drives me nuts! Whatever the previous owner was thinking...