Help Please Audi A4 3.0 TDi CCWA idle issues

[Gooders]

Hello all.

Last night just before parking up I had a strange idle issue.
The idle was hunting and I was only able to keep her running by applying more rpm. When I let off she stalled. I checked on vag com and had the normal p0401 egr flow fault I have been getting on and off for years but I also got a p0638 throttle body actuator bank 1 fault, around the time of the stall. So I cleared the codes fired her up and all seems fine apart from the idle which is about 650 rpm. Having read other treads it should be nearly 800. And one out there had this issue before?

Cheers


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[Gooders]

Any one with a 3.0 tdi ccwa able to tell me their normal idle rpm ?


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[tech838]

600-650 is about right when it's hot. They tend to idle at 800 when cold.

On a CCWA (or any TDI) a P0638 will be for your anti shudder valve. If it's sticking it'll restrict the intake and cause the engine to die. But it does a full sweep every key cycle so would explain why it fired up fine after.

 

[Gooders]

Thanks for your reply. I have taken it out a few times and have the same as you said. Huh when cold low when hot. Really put my mind at rest.
Any idea why it happened? Is it the start of a failure or just one of those things?


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[tech838]

The ASV is right behind the inlet for the EGR and some oil and soot tends to accumulate around there gumming up the flap in the valve, or sometimes the motors do go bad with age (but rarely).
It's fairly easy to clean if it happens again and you're that way inclined .

 

[Gooders]

The ASV is right behind the inlet for the EGR and some oil and soot tends to accumulate around there gumming up the flap in the valve, or sometimes the motors do go bad with age (but rarely).
It's fairly easy to clean if it happens again and you're that way inclined .

Well following on from advice from tech838 and the fact the condition got worst I ordered a replacement part.
It got to the stage were when stopped at a junction it would hunt and cut out all the time.
Once removed the valve was very dirty and when the butterfly valve was moved it was slipping the gears and very rough in operation. New one in, cleared codes, test drive and a few long runs (300 miles) and all seems well.
Thanks for the advice.

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[Gooders]

I have seen repair kits, but as I need her work went with the new part.

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