The other day when I was driving, I hit an unannounced dip in the road and immediately after, my car was shaking throughout driving, and was worse at lower speeds. At faster speeds, my engine check light will flash (which means my catalytic converters are burning up, right?) which makes me feel like I need to slow down. After I had hit this dip in the road, my car was producing a sewage like smell in the air, which everyone in the car could smell. I drove it again today, after 2 days of not driving, and for the first couple minutes the car seemed to run fine, but then it started shaking after it had ran for a little bit and continued to get worse the more I drove it, which lasted about 5 minutes.

Can anyone tell me what they think is wrong with my car? I assume I need to replace the catalytic converters, but I don't know how right I am.

I drive a 2001 Audi A6, 2.7T with 164K miles on it

 

If you smell something like rotten eggs this COULD be an issue with the cats. You wanna scan it for the codes before throwing that kind of money at a 2.7T. I have one myself, and I know cats aren't cheap.

The shaking could actually be from a misfire, though. When you say "dip" do you mean a ginormous pothole that you could possibly go swimming in? Though highly unlikely, depending on the magnitude of the jolt, one of your coils could have come lose, though this is VERY unlikely due to the amount of force that must be applied to remove one.

Scanning your car for codes at a place like Autozone is your best first step.

 

I'll scan the codes at Autozone sometime today then. Should I be driving it?

 

Driving your car around with a mystery ailment is subject to debate. To be on the safe side, I honestly wouldn't drive it any more than you have to at this point, and even that may lead to more damage depending on what it is. Certainly, if you do drive it, DO NOT drive it like you stole it.

If your CEL is flashing, it's most likely an indication of a misfire issue. Let me know the codes and I'll try to help.

 

I have 3 codes.

P1423
P0300
P1113

None of these codes tell me what cylinder is misfiring (I assume, Autozone said it was saying RANDOM misfire)

The code that I think is the problem is P0300, which says:
random cylinder misfire detected
Explanation
Lean air/fuel ratio
Probable cause
Ignition system misfire system
Fuel injector fault
Engine mechanical condition

Here are the rest of the codes
P1423
1 Secondary air injection output too small
Explanation
Check air system for leak
Probable cause
Failed air pump

P1113
Heated oxygen sensor - Bank 1 Sensor 1 (H02S11)
Heater resistance too high
Explanation
Open or short circuit condition
Probable cause
Failed H02S11 (Bank 1 Sensor 1)

If anyone can decode these and give me the most likely problem for all this, I'd be more than happy and grateful. My spark plugs are prettty much brand new, and were put in with a torque wrench. I don't know how old/new the plug wires are, or any of the coil packs.

 

Sounds about right. The shaking is more than likely from a misfire (failed or failing spark plug or coil pack). If the check engine light is flashing do not drive the car. If its on constantly its OK to drive.

Sounds like you need an o2 sensors as well. Check the hoses and connections going to the SAI pump. It could just be a leak.

Good luck!

Jason

 

What should I be replacing? Considering my spark plugs are brand new, I don't think those are the problem. Should I be replacing the wires for the plugs? Or the coil packs?

 

Your vehicle doesn't have plug wires. You have coilpacks that sit on top of the spark plugs.

Usually you should get a code that tells you which cylinder is misfiring, with out this you would be blindly guessing.

Jason

 

slim chance but if you happen to live in the Boston area i'll happily hook up my vag-com to your car so you can have specific codes to work with.

 

Your p300 code maybe related to a bad ICM. With that amount of miles on it, I'm willing to bet they are the original ones, and they are probably on their way out. When they go bad they will wreak all kinds of havoc on your firing sequence and overall performance.

You should find two ICM units either on top of your air filter box or very close to it. Swap them around and see if the issue goes to another cylinder. Of course, you will only know this if you have a VAG-COM.

Here is a link to how much they cost and what they look like:

Audi C5 A6 Quattro 2.7T > Search > Ignition Control > ES#10206 Ignition Control Module - Priced Each - 4A0905351A