Good morning. I've had some issues as you'll soon see, but I'm tiring of the dealer, so I'm going to attempt some DIY even though I don't really have the time.

My vitals:

03 A4 1.8T w/ 97K mi

Here's the fault codes I got this morning after a trip to Advance:

16684
P0171
Fuel Trim,Bank1 System too Lean
16684
P0300
Random/Multiple Cylinder Misfire Detected
16685
P0301
Cyl.1 Misfire Detected
16686
P0302
Cyl.2 Misfire Detected
16687
P0303
Cyl.3 Misfire Detected
16688
P0304
Cyl.4 Misfire Detected
16891
P0507
Idle Control System Higher than Expected

I imagine from reading many posts here this morning I'm likely in need of 4 new coil packs. I have checked the existing coils while it was running and number 4? (closest to firewall) was the one not firing. But I'm not sure where to go from here or my next best steps to take. Should I do the CP's first and then get another code check?

 

You may have more than one problem here but you should fix the P0171 and P0507 first before working on the misfire P030x. An large air intake leak will cause the P0507 and P0171 and also cause the misfire at all four cylinders. With engine running at idle, try to listen to any hissing sound. You can wigle hoses and especiallly any plastic component to find the crack.
Note: Poor performance MAF sensor will set code P0171 too. Try to locate and fix any intake leak first.

 

(Sorry i posted this in another thread also.. this one is just way more recent)

I am getting the same P0507 and P0171 codes on my 06 2.0T..

Do you have any issue at all with your idle? I do. The Idle goes up to like 1200rpm most of the time. Sometimes up to 1500.. and rarely, itll stick at 2000rpm, then go back down after a second or so. It does constantly stick at around 1200-1500rpm though.

Its not all the time though, when i first start the car, its fine for a bit, and then once it starts, it keeps fluctuating. Cleared the codes, tried to do the readaption of the throttle body, nothings changed. Was hoping i would get another code which would help pinpoint the issue but always only those 2 codes.

Have you found the source of your issue Gato? Any info about how your car is acting?

 

its very unlikely that the 4 coil packs would go at once. it has to be something before the cylinders. im not sure what the b6 generation has for sensors but i have a b5 s4 and i had a ingition control modelue that was bad and i had three of my cylinders mising.

 

BerinG,

treelimb was right on(thanks!. I listened for and found a vacuum leak. It was a crack in the 3-way valve that sits on the backside of the air intake manifold by the firewall. Once I replaced that it ran smooth again.

I still got a CEL and flashing PRND when driving it down the street today to get an oil change but it's still pretty smooth. But I haven't had a chance to drive it or get another code reading because I've been out of town. The Audi parts guy I spoke to said the continued CEL could be due the non audi oil filter he spotted the numbskulls(now fired) at another local shop had put on. He mentioned there's a check valve in the filter to help regulate pressure that could be contributing.

Once I get it back today with the proper oil filter I'll get another round of code checks and let you know what I find. Good luck!

 

Well nothing went well after the oil change. It ran, but not like my drive after replacing the air valve. I then left for the airport the next night and was surprised I made it.

With about 5 miles to get there I had another flashing CEL and shuddering like its only firing on 3 cyls. again. When I get there I lift the hood and the entire exhaust manifold on the lower left of the engine bay is so hot it's actually glowing red. I doubt that's normal.

I get back from my trip today and again get about 5-8 from home and the same flashing CEL and misfiring return. I'm checking for more vacuum leaks again but there's likely more going on here than that. Any other possibilities? MAF?

 

There may be more intake air leak but you reported the engine is running smooth and no high idle. This time i would go after the ignition coil(s) ASAP. It is going to destroy the cat converter. Check for trouble code then go from there. I would replace all four ignition coils.

 

Thanks for the info guys.. i'm still having this problem.. I left the cel on for a while now.. i just hope i can get another code or something caus p0507 and p0171 are pretty general.. I am now thinking it might just be the throttle body not staying closed, or maybe too dirty, it gets stuck while trying to close.

My friend said he can bring a propane tank so we can check for leaks.. will see what happens