New fault? Do not exceed 4,000 rpm

[Stiggles]

I recently changed the air filters on my 6 for the BMC variety, when maneuvering the inlet pipe about I think I may have put pressure on the hose which connects the oil reservoir and the oil separator, pictured below the BMC box, and the pressure caused the oil separator end to fail to fully seat. I've ordered one from TPS but have since been getting the following error show up any time the car is driven harshly





Now since this fault has only started since the air filter swap I'm assuming it's related to the hose, but I have gotten several N249 valve errors in the past while and am starting to wonder should I replace them?

I've also seen the N75 valves give trouble and my cars coming up to 170k miles so was thinking of swapping them out as a precaution

Hope someone has some advice as I can't seem to find anything on this particular fault

[Stiggles]

https://drive.google.com/file/d/1-0k0Am ... p=drivesdk

https://drive.google.com/file/d/1-JsqoL ... p=drivesdk

[welwynnick]

Can a healthy RS6 rev above 4000 rpm in neutral?

Nick

[Stiggles]

Can a healthy RS6 rev above 4000 rpm in neutral?

Nick

Not whilst stationary I don't think, but it can redline in neutral if the car is in motion, you think it might be gearbox related?

[Jim Haseltine]

That end of the hose is very difficult to seat properly - I was quite surprised that mine fitted at first attempt a couple of days back.
There are a lot of pieces around the RH airbox that are not easy to fit, so first principles - you did refit everything didn't you?

[Stiggles]

That end of the hose is very difficult to seat properly - I was quite surprised that mine fitted at first attempt a couple of days back.
There are a lot of pieces around the RH airbox that are not easy to fit, so first principles - you did refit everything didn't you?

I did try several times and I assume it's had a hard life with the mileage, but it's definitely not seating as there are two teeth on the plastic clamp and one side is basically worn away to nothing with the other being barely there, I will give it another go to make sure, but a replacement is en route regardless

I definitely put everything back the way it was, I even checked and checked again that all the small vacuum lines into the air box were snug

If I turn the engine off the 4000 rpm limit warning disappears and allows normal operating again until driven rough where it displays again. This leads me to believe it's boost/vacuum related

What is the function of the hose from the oil reservoir to the oil separator exactly?

[Jim Haseltine]

It's part of the PCV breather system. The thin ribbed hose takes crankcase fumes to the coarse separator in the top of the oil reservoir while the thick pipe then takes those fumes and air from the oil pump return (the turbo oil return lines have air fed into them at high revs to stop the oil being extracted too fast from the turbos) to the fine separator in the PVC/separator. The oil then drops from the bottom of the separator into the RH cam cover. The remaining fumes are then directed to either the inlet manifold or the front of both turbos depending on throttle position - as long as all three non-return valves post separator are working correctly, at 110K miles two of mine were locked in the return position.

[Stiggles]

It's part of the PCV breather system. The thin ribbed hose takes crankcase fumes to the coarse separator in the top of the oil reservoir while the thick pipe then takes those fumes and air from the oil pump return (the turbo oil return lines have air fed into them at high revs to stop the oil being extracted too fast from the turbos) to the fine separator in the PVC/separator. The oil then drops from the bottom of the separator into the RH cam cover. The remaining fumes are then directed to either the inlet manifold or the front of both turbos depending on throttle position - as long as all three non-return valves post separator are working correctly, at 110K miles two of mine were locked in the return position.

Sounds like that's my fault then, the car will drive at full power but every so often will cut out, turn it off and on and the warning goes away

New hose is due today so will get that fitted and see what's what, tried several times fitting the old one properly but it's just not seating correctly so I hope it's the hose and not something on the end the hose clips into

Have had a few N249 faults but trying to get to the bottom of them, they haven't thrown up this issue before