difficult to start and rough initial idle, related to 17585 code?

B6 A4
#1

Hi all,

For the last few months I’ve had a progressive difficult to start issue. The car will crank but won’t start until 12-20 cranks. Has a rough idle for the first 30 seconds to minute then it runs just fine. Lots of smoke and unburnt fuel initially. Definitely more frequent if the engine is “cold” (although I moved to Houston so more like hot ambient but cold relative to running temps). No CEL but I finally got around to scanning it and got 17585 code, “bank 2 lambda correction downstream of catalyst: control limit attained”

For what its worth, I have JHM tune and JHM downpipes with relocated HFCs. Houston requires inspection with emissions, so I probably have to replace the O2 sensors anyway. The car has 93k miles and on original 15 year old O2 sensors so I should just bite the bullet and replace them all. But I wanted to see if it makes sense if having a bad “post cat” O2 sensor (which is really still upstream of the cat b/c of relocated high flow cats) would cause such a problem or should I try something else in the meantime?

Thanks for any insight

#2

I’ll take a shot in the dark and ask if you’ve replaced your fuel filter? IIRC, the check valve is in the filter, but if not, then the check valve on the fuel line. If it’s not holding, essentially the fuel drains back from the engine to the tank and you need to re-establish line pressure before it’ll fire. I’ve dealt with this on a different platform and sounds eerily similar.

#3

The check valve is on the fuel pump assembly as far as I know. In the 04+ models, the pressure regulator is in with the filter, 03 and earlier it is on the fuel rail.

Sent from my DROID Turbo 2

#4

Did You do a full autoscan or just look for CEL codes?

Try running a full autoscan?
You may find something else there?