View Full Version : PCV related to rough idle

07-26-2008, 10:45 PM
I've been having a rough idle without any CEL's and I've tried chasing it down as I've described in this previous thread and have not solved the problem:


The problem started soon after i replaced the 90 elbow tube on the hose of the secondary air inlet up top by the injectors. As well as the quick connecto hose to the secondary air injection pumpmotor.

After researching a bit more I think the rough idle is related to the Charge pressure regulation system. I've already had some check valves, recirculatin valve (710N) and some hoses replaced under normal maintenance conditions. I know the N75 (wastegate/bypass regulator) hasn't been replaced, neither has the pressure regulating valve,or the combination valve for the secondary air injetion.

I've also checked out the link below and I'm thinking about replacing the breather valve.

Basically, I don't know where to start any suggestions woudl be appreciated.

07-27-2008, 04:27 PM
21 views no responses?

Where are the Guru's?

07-28-2008, 09:42 PM
Now I'm thinking it could be that the Secondary Air Pump is going bad.

I hear whinning from inside the cabin. The whinning seems to be coming from somewhere around the air box.

Once again, any thoughts appreciated.

07-30-2008, 09:45 AM
I've read that a damaged flywheel could be causing the rough idle as it would be unbalanced.

My clutch is slipping and doesn't hold 2nd gear really well after a quick launch.

07-30-2008, 01:05 PM
Have you tried a throttle body adaption?

07-30-2008, 02:10 PM
Yup, took out the TB and cleaned it with cleaner and did the adaptation (i.e reset ecu by disconnecting negative battery cable).

08-02-2008, 03:47 PM
Alright, replaced all of the check valves and some tubing underneath the manifold, all of which seem to be operating correctly.[wrench]

Repalced the the N75 and Wastegate valve, which had oil leaking out if it, is that normal?.[wrench]

Recently, I noticed that the turbo has been glowing red under "normal" driving conditions.

Could a bad catalytic converter cause the rough idle?

Can I run the 200 HFC from Milltek in Cali and pass emisssions?

08-14-2008, 12:09 PM
I would start with testing ICM (I doubt it is because you said you have no flashing CEL) and if that is good clean the MAF or unplug it (your choice or do both) to see if there is any improvement, if not then follow the inlet hose from the Air box to see if it is secure and for cracks, if it is not cracked or loose, then follow the hoses all the way to the intake manifold. (All the turbo hoses underneath the car too)

I think your cat is glowing because un-burnt fuel is entering it and I would suspect that you have a crack or loose inlet hose or turbo hose.

08-16-2008, 12:44 AM
Check your spark plugs.... If your running any mods your plugs need to be replaced more frequently. If you pull them out and they have a dark ring above the threads I would replace.

08-21-2008, 09:45 PM
So I delivered my car to La Jolla Auto Tech and the owner's a little old school, but a complete pro and has been working on Audi's and P-cars for the past 25+ years. He checked timing and all was good in that department. Bottom line was the Combination valve was bad and it needed to be replaced.

Car is running strong and all is back to normal.

I'd like to thank everyone who contributed to this post and I hope this well help someone down the line.

Until next time..

Here's another post of mine on a different site, with some more info.