The last one I bought was a cheap Duralast from Advance Auto. The one before that may have been a Beck Arnley or Beru unit. The Duralast was about $30. The original units on mine are made in Japan (I can't remember the name). I think I paid about $70 for it but I can't say for sure. That was 5 or so years ago. No issues so far. Partsgeek has OEM and Bosch units for under $40. Don't pay the extra $50 for the Audi Box, if you know what I mean.

 

So I bought an Import Direct coil from O'Reilly's yesterday for $22 with the primary purpose to just see if I could just fix the shudder and then if it works, replace all 8 with OEM. I will step through what I did exactly, because my car is MUCH better:

Disconnected and pulled out the coil from cylinder 5, which had been the primary culprit of CEL misfires. I put the new one in and securely connected it, which was all surprisingly easy. I started my car up fine and idled which it did fine before, put it in reverse, and then the shudder came and the CEL came on.

I threw it back into park, turned it off, and popped the hood. I pulled the ID coil out and closely examined both the ID and oem coils... pretty similar with some differences on the inside where it makes contact with the plug. Not doing much else, I reinstalled the old oem coil firmly and reconnected. It started right up as expected and I cleared the CEL. I put it into reverse, and NO SHUDDER. WTF? I had to run errands so I drove it for about 45 minutes stopping/starting/accelerating and it essentially was FIXED. Smooth power and acceleration was back. I was overjoyed.

I started it again this morning cold. While there was still a bit of a shudder going into reverse right away, it pretty much went away and it drove into work (15 miles) great.

I'm going to see if I can pull it out and possibly clean it or something more... i really don't know. All I know is the dealership basically said it couldn't be "fixed" and the car had to "learn" again...

 

Interesting.. It's possible that the ID part is defective out of the box.. The OEM coil you put back in may be starting to go bad. They can misfire when cold but when they warm up, they might act just fine again. Take the ID part back and get a Bosch unit. Be sure to put a dab of dielectric grease in the hole where the spark plug fits into the end. This will prevent any moisture that may (it's not likely) be forming in the tube from being able to short some the spark to ground before it makes it to the spark plug. You might even pull the spark plug from that hole and inspect it. If you see any tiny round deposits that resemble welding spatter, it's glazed. If it's black, spray it clean with some carb cleaner spray to remove the black soot (which can also conduct and weaken the spark).

 

So finally got time to go digging around the air filter box. First, looks like it hadn't been changed in a while, which is kind of annoying since my last two oil changes were at dealers. Second, I looked all around and even unscrewed the bottom half of the box to see lower and didn't see any gooey hoses or anything.

Did notice at some point that accordion hose connector was installed upside down and that was why it wasn't connecting correctly. I mean, I noticed after I pulled it out and saw the arrow... I think I need a new one cause it seems permanently warped.

Going to start playing the swap game with the coils. When the car runs up after about 5min it drives SO smooth, which is annoying. Would really like to fix this cold-start rough idle situation.

 

A bad coolant temp sensor can cause rough idling and hard starting issues. If switching the coils out doesn't fix the issue, I'd try that. Temp sensor is located in on of the metal coolant lines, usually on top near the back of the engine. It is held in with a plastic clip. Really easy to change. I recommend getting a new plastic clip with the sensor if it doesn't come with one. The things get brittle and can break when removing them. The sensors cost about $20.

 

As the saga continues for those reading through this: I decided to dig deeper into the coil situation. When I pulled 5 it looked fine so I thought nothing of it. I had also gotten a 0304 so I decided to pull and look at Bank 1 coils. HA!

Here is just one of the ignition coils but they all had varying degrees of ??? all over them with some sort of corrosion on the ends.




I don't know what a good coil cylinder is supposed to look like but here is #4 which had misfire reports.



So I pulled and cleaned all of Bank 1, put dielectric grease on the insides, and reinstalled. As one would expect, car runs much better and the rough idle is almost completely gone.

I've been driving for a couple days with no CEL coming on. I was on the highway today and pushed it to about 90ish trying to break 5k rpm. It ran well but the CEL did come on with the same 0174 and 0305. I'm thinking I'm going to pull the #5 plug and inspect.

 

Cool beans.. Crud in those things can really redirect the spark...

Swap the number 5 and 6 coils around. Run it. If the CEL comes on and it gives you a 0306 code, it means the misfire is following that particular coil. If it stays on number 5, it's probably the spark plug.

 

Alright - so two days ago per dave944's suggestion I deepened the fault isolation. I pulled, inspected, cleaned, and swapped 5 and 6 coils.

Not a whole much of a difference, as in general the car is running much better. Went about 1.5 days without a CEL and it came on during my drive this morning. The 0174 Bank 2 Too Lean is a reoccurring code that I think is now the real problem I need to tackle. Not sure when I'm going to get to it, but it looks like all the hoses are fine so far... was really hoping to find a smoking gun.

 

I bet it's the flex joint in the exhaust just ahead of the cat convertor on the drivers side (bank 2). Even a tiny hole will cause it. The O2 sensors are that sensitive. I eliminated the ones on mine after I replaced them once only to have them come apart again in less than a year. The exhaust is mounted on rubber mounts so any flexing that the engine may induce isn't going to bother anything. NONE of my other cars have these stupid flex joints so..

One other thing to check though.. With the car running, loosen and slowly try to lift the oil filler cap on the valve cover. If you feel it being sucked back onto the valve cover, the PVC Valve diaphragm is leaking. This can also cause a lean reading. It's the round pancake looking thing on top of the engine near the rear. About 3 inches in diameter. $30-40 part. Easy to swap out. Just replace the crimp clamps with some suitably sized spring clamps. I've gone through 2 PCV Valves on mine in the past couple of years.

 

Wait wait wait... the valve cover gasket was supposedly leaking and that was one of the TWO things they supposedly "fixed" when I first took it in. Very sarcastic question, but what are the chances they messed this up even though they supposedly "checked their work" when I took it back? I did another test last night while I'm waiting for all my torque wrench stuff to arrive... I sprayed ignition fluid around the engine with absolutely no difference EXCEPT right around cylinder 5 which is coincidentally right where the oil cap is. I don't know, but I'm still going to check the #5 plug and switch stuff around but I'm thinking I might (somehow) check their workmanship on the valve cover gasket.