Emission control light on

[doublea]

Hi,

I'm looking for some technical guidance. The Emission Control System light came on yesterday, when driving on country roads with the engine warm. The light stayed on, constant after re-starting. The engine revs have been a bit uneven lately, at idle, floating about 1100rpm. Yesterday, they were again uneven when coming to a halt, but slightly higher at about 1200. When I blipped the throttle, the revs stayed at 2000rpm until I switched off the ignition.

There is no difference at cruising speeds, or when accelerating/slowing. I feel the exhaust note is louder at idle and there is no appreciable change when switching to sport mode.

I don't have access to a code reader, but am hoping the symptoms are familiar to someone, in case it is something I can check myself, rather than paying £90/hour!

Cheers, Angus

[doublea]

PS,

the car is 2006, 43,000 miles and completely standard.

Angus

[Ranger Rico]

I had this just a couple of months ago, everyone will say coil packs which is mostly the cause, i have a VCDS and it showed an intermittent open circuit on one of the cylinders, i swapped over the coil and spark plug between the faulty cylinder and another working one but the same fault appeared on the same cylinder.
I noticed that the wiring loom that goes to the 4 cylinders had a broken clip on it and im certain that this was causing the fault as i tightened the torx screw while pushing the ignition coil contact and the fault has gone.
I should really get a new part to replace the broken one, i will do when i get the chance.
Ill be back in portlethen early next month if you can hold on or im sure another aberdeen VCDS owner can perform a code check.

[adsgreen]

High rpm sounds more like a vacuum leak.
Coil packs cause low rpm and rough running.
A vac leak can mean more unmetered air raising the rpm limit.
Can also cause rough running around idle.

Aha - if the valves are not closing then 100% vacuum leak.
Start the car in non sport mode - the valves in the exhaust should close after a few seconds.
Easy to see them if you peak up the pipes.
Check both vacuum actuated are connected - normally a vacuum leak in the engine will make the valves rattle as they have their own reservoir. If they don't move a not then either a bit the either a bad leak or a pipe has come off the exhaust actuator. You can spot these if you lay on your back under the exhaust box. You'll see a round thing bolted on the inside of the box which should have a black pipe attached.

Get the code read - doesn't have to be official vag-com as any odb2 reader will give a hint.

[doublea]

Thanks for the replies.

The coil packs were changed last year as part of the recall.

I'll nip out and check the pipes around the exhaust valves. Hope it's something fixable. Maybe my local garage that does the mot can read the fault codes, if I don't see anything obvious just now, I'll nip in by there tomorrow.

Cheers, Angus

[adsgreen]

Code wise you may have p2020/p2015 stored if vacuum issue.
Indicates the manifold intake flaps are in the wrong position. Happens as they are moved by vacuum.

If exhaust valve connection then easy fix. I used small jubilee clip when mine popped off.

Otherwise more tricky to find and fix. There's some good stuff in the forums.

[doublea]

Update:

I checked the pipes at the exhaust valves; they look ok. The valves are opening and closing again.

Dropped in at the local garage, mechanic read the code as P0171, running lean, left bank.

Is there anything further I can check?

Thanks, Angus

[adsgreen]

Not easily...
It still sounds like a vacuum leak and given the transient nature I would say it suggests the one way valve that is (un)helpfully located under the intake manifold.
if you have a decent spanner wielder then you could try removing the front carbon engine cover (just pulls off) and pluggin in a vacuum tester (gauge + hand pump) to the double T piece. If you search the archives you'll find info on what each one does.
Essentially you unplug each one and test how well it can maintain a vacuum. shouldn't drop at all in about ten minutes.

Running lean is also a sign that air is getting into the system and the vacuum system is the likely culprit.

[doublea]

I had a poke about the pipes under the cover near the oil filter. I couldn't see any perished or split pipes. Subsequently, the eratic idling was much worse, the car barely driveable at low speeds and the revs sitting at 2000rpm waiting at traffic lights, etc. Upon shutdown, there was a sucking noise followed by a noise like a flap shutting, in the vicinity of the oil filter housing, the noise lasting for a very short time, maybe less than a second.

The service was booked in for today anyway, so the fault has been traced to a breather valve near the inlet manifold. I'll post up a photo of it when I get it back from the garage.

[Les]

Doublea where are you servicing the car? Is it at Audi?
I have just had multiple amber lights on but it has cleared itself, as the guys on here said it might, but in my case think it's possibly going to need a maf sensor soonish.

[Ranger Rico]

I've yet to have the RS into a garage but I've been recommended the Volks centre in kingswells rather than the stealers

[adsgreen]

The "oil breather" on the B7 RS4 is (IIRC) actually the cyclone oil separator. It's designed to filter out oil in the intake system and periodically open a valve and drop it into the sump. I also think this is a common point of failure and can cause vacuum issues (as I suspect the valve is vacuum powered).
I wouldn't be surprised if it didn't cause some extra oil residue on the valves.

[Les]

Rico - I used them when I had my first RS4 (B7). They changed the brake discs and pads on the front for me and they do a great job and decent to speak with. They also allowed me to source the parts and they were happy to fit them

[doublea]

Using the local audi garage, £96/hour!

Valve 079103464f (see photo) replaced and engine back to normal.

Also, the friction material on my rear pads had disintegrated, I think due to corrosion between pad and disc. Quoted ££876 to replace discs and pads!