my vRS over the last couple of months has been really rough on cold idle - revs will go up and down and generally feel rough.

I've scanned with my Liquid Gauge and got the following error codes:

17544 - Fuel Trim: Bank 1 (Add): System too Lean

16891 - Idle Control System RPM: Higher than Expected

16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit

Things I've recently done to the car to both fix this issue and generally improve performance:

Replaced CTS with new green version

Throttle body clean and adaptation with Vagcom

Carbonio CAI and Pipercross cone

Shark Stage1 Remap

Catch-can & partial breather replace

Genuine N75

Forge DV

My next steps to try and fix this is check the breather pipes under the inlet manifold (around dipstick) & maybe replace MAF. (Any guides on the breathers under the inlet?)

Any other ideas? Thanks for your help guys!

Did you sort out the 16514 code? If you didn't that could well be the problem.

The breathers by the dipstick are easy to access once the black plate on the inlet manifold is off. Check that the dipstick receiver isn't cracked as that can cause rough idle. There's a PCV on the breather T piece to the right of the dipstick that often fails too

Edited 6 December, 201114 yr by pauldazzle

Did you sort out the 16514 code? If you didn't that could well be the problem.

The breathers by the dipstick are easy to access once the black plate on the inlet manifold is off. Check that the dipstick receiver isn't cracked as that can cause rough idle. There's a PCV on the breather T piece to the right of the dipstick that often fails too

thanks PaulD - no haven't done anything with the oxygen sensor error. I wondered how much these error codes are inter-linked.

Does this look like the right hose for underneath?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160693798316&category=72205&_trksid=p5197.c0.m619#ht_1664wt_952

Yup thats the one, I replaced all my breather pipes with there stuff, not bad altho have to mod a little to get to fit right altho i am abit sad when it comes to stuff been right

thanks PaulD - no haven't done anything with the oxygen sensor error. I wondered how much these error codes are inter-linked.

Does this look like the right hose for underneath?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160693798316&category=72205&_trksid=p5197.c0.m619#ht_1664wt_952

I'd advise you sort the Lambda out before you go any further. There's a lot of heat generated off the exhaust that can cause the Lambda wiring to fail.

Yes that's the pipe that runs from the underside of the inlet manifold to the top of the small PCV valve that sits in the large T piece pipe on the engine block. All of the pipe work under the manifold is prone to splitting, so you need to inspect them closely as often it's hard to spot splits with the pipes in situ. There are 2 small braided pipes around the inlet manifold that split under the braided covering, which are obviously hard to check. I'd just replace as many pipes as possible.

Edited 6 December, 201114 yr by pauldazzle