Hi guys, I have a engine light on and a "shaky" rough idle, Hooked up the V-checker and my 7 P-Codes are the following...

P0507: Idle air control system: RPM higher than expected.
P1297: Connection charger to throttle valve: pressure dropped
p0300: Random/ multiple cylinder misfire detected.
P0301: Cylinder 1 misfire detected.
P0302: Cylinder 2 misfire detected.
P1128: Bank 1 mixture adaption (mult): system to lean
P0171: System to O lean bank 1.

I had the engine light come on last week, in which I took apart my vacuum lines/ crankcase ventilation system hoses, and just made sure nothing had a tare or a hole or crack in them. I did however find a small crack in the "3-way breather hose that connected from the bleeder valve to the top of the valve cover, in the back. I macgyvered a temporary fix for it, while waiting for a new diverter valve & bleeder hose from ECS. After fixing that small crack with some handy work, the light went off. Has been off now for the last week, today however it re-appeared, I understand that the hose needs to be replaced, Im waiting for it to arrive any day now, but i can assure you my new lights are NOT attributed to it. Also 3 months ago I replaced just about every single hose from the Stealership at high price the only thing i did NOT replace was the PCV Valve, However again, I DO NOT notice any leak or any reason to believe that it is indeed faulty at this moment.

Does any have any suggestions? thanks

QUICK UPDATE: I took off the oil cap and found no change, however I pinched the lower vacuum hose on the intake manifold and the rough idle subdues.
-I have now ordered the PCV Valve (just to be safe, its a high failure point)
*25 views from "die-hard" audi fanboys and no help? I expect my parts to be in several days, I will install and follow up as a record for future people with the same issue. I have noticed many fourm members posting about the same issue and their seems to be a ton of advice- me personally after all I have experienced with this B6- seems to always be the vacuum system.

 

Crank it up and, while it's running at idle, loosen the oil filler cap. Slowly remove it. If you feel it being sucked back into the opening, the PCV valve is probably the culprit. I've put 2 on my A8 in the past couple of years..

 

Well I just got done changing out the PCV valve tonight and threw it all back together, started her up and found the idle to have gotten worse not better. The Vag picked up an additional 2 more codes. Cylinder 4 misfire & P1297: Connection charger to throttle valve: pressure dropped, combined with the original P codes from above.
I can for 90% sure eliminate the vacuum system I have 10% doubt because I suspect my bleeder valve could perhaps be faulty.
I now suspect the culprit to be the Mass Air Flow Sensor, I suggest this because the one thing (other than vacuum) that all these codes share in common according to Ross Tech is the MAF. I actually took it apart today, and hosed it down with CAF M.A.F Sensor cleaner, that is supposed to be safe fore cleaning the sensor. Still no luck. I have also now cleaned out the throttle body tonight as well and soon to do a throttle body alignment tomorrow when I pick up my gasket for it.
I have the "Bleeder Valve" and the DIverter valve coming Fri, I will keep this post updated until I find the cure.

 

UPDATE: The car is now running and idling smoothly + my P-codes have all disappeared. I changed the PCV Valve plus I was able to perform the Throttle Body Alignment tonight,
(see forum member for details DIY: B6 A4 1.8T - Throttle Body Cleaning)
I also noticed tonight after touching my oil dip-stick tube that it pretty much just fell apart, literally. I hardly touched it and it cracked and splintered and fell apart, I managed to macgyver a quick fix until I am able to replace it. I'm just wondering if my vacuum leak could be faulted to a hole in the oil dipstick tube? If so did that indeed lead me to 9 P-codes?

This forum has been a big disappointment, over 250 views and no-one had any advice, input, or help. I first decided to ask and post my experience because after googling my issue I found many who have posted the same problem with no cure, or ones not alike. I just hope my thread is more help to the next then the others were for me.

 

No advice, input, or help? What was it that I posted above?

Yes, the oil dipstick can also allow air to be sucked into the engine just like a leaking PCV Valve. But usually that is not the problem because not a lot of people bother to check their oil often enough. ;-)

 

Yea Dave944 you were help, I'm just surprised there's not more people on here with experience or knowledge on these cars. But last night I went back a couple pages on the forum and saw many people with questions and you were the only one to answer them I noticed. Are you single handeling running the general tech section? Anyways thanks for the help.

 

No problem.. Yeah it is kind of slow on here and I see what you mean.