Mar48

I know there are countless threads on this issue but most are pretty old so wanted to see if there was any fresh perspectives on the rough idle issue.

2006 Audi A4 Avant automatic w 77K miles (it's for sale I haven't purchased it yet - currently getting a PPI done). It has a rough idle, it's not absolutely terrible but still very noticeable and WAY more noticeable at idle if I turn the steering wheel or the car.

Ive heard to do the N80 valve and tranny/engine mounts. I see countless other things to try. Does anyone have a real idea on the solution to fix a rough idle on a B7 automatic?

maverick17036

I haven't had the problem but I've read a lot of threads on here about the torque converter. N80 valve is a simple DIY that you're gonna have to replace sooner than later with that mileage. Probably best to switch it out anyway. I've had to get my engine mounts replaced due to the engine moving too much when accelerating. Not sure if that will fix your issue.

jiggysmb

coil packs/plugs, $200 fix!

John535is

Assuming you don't have a scan for any error codes, I always start with a vacuum check. The ECU's on these are actually really good at compensating for small vacuum leaks so it actually masks the problem well.
I assume its otherwise running well with no other symptoms to report.
Grab a flashlight, remove the plastic engine covers and just have a good look around, you are looking for cracked or broken vacuum lines, maybe a loose connection. Give the hoses a bit of a shake, check the bends for cracks, particularly the crankcase one can crack in the heat. As these engines get older, the rubber lines are getting hard and cracking with the engine heat. This will cause the poor idle.
Costs nothing to have a look, there are lots of other things (poor coils/plugs, PCV, N80 etc) but without a scan you are guessing and potentially spending money unnecessarily.

Boostlee

so I had similar issues with my B7 and a failed cylinder 3 code. So I got new plugs and coils and figured since I was at it I would add a boost gauge and maybe swap out vacuum hosing. Seemed simple enough But with so many hard hose ends, I am not clear which ones are vacuum lines. I also can’t find a place to tap in to for the boost gauge. Let me know if I missed this information in a different post! Thanks

Kris Hansen

Scan it for codes. Then come back. If it's a lumpy rough idle, could be pcv related, or other vac leak. If it's just coarse, could be normal for the engine. The 06 is not a smooth engine.

Boostlee

Thanks all for the help. I scanned like five times since autozone is like 3 blocks i am able to get it over there. I think it’s the line going through the sheet metal just before the firewall near the battery. It’s a vac line of some sort that I can’t seem to ID. I changed he Pcv already as wel.