Vacuum check valve

[wjam]

Chaps (and chapesses)

Can someone clarify for me which way round the vacuum check valve should be (plastic - white on one side and black on the other)

I just took my car to diagnose a fluctuating idle and cut outs when hot, and they want to change the hight pressure pump and 1 of the variable inlet flaps (3.0tdi) for the princely sum of 2.5k euro... and my "guarantee" only covers 1500 for any 1 intervention... not pleased.

However I ask the question because they swapped the direction of this vacuum check valve during the "diagnostic" without any explanation.... And me smells a profiteering rat.

thanks in advance

WJAM

[wjam]

OK so black side seems to be vacuum side... How come my car has the same symptoms either way.. and in fact the EGR etc worked when it was the wrong way round???

The mystery continues

[gupsterg]

Hi,

I have been doing research and it seems to suggest that the "Vacuum check valve" on certain VAG models can cause idle rev fluctuations...

I have a 2005 3.0 TDi which has an intermittent idle problem...

I've already done...

1. New throttle valve body
2. New MAF
3. Last P/N & rev of ECU software
4. Full set of Injectors
5. Cleaned EGR inlet port on throttle body adapter, due to clogging was causing MVB 03 to be out
6. Most hoses and wiring checked
7. New N18 (059 906 628 B) vs my old 059 906 628 A
8. As I couldn't easily gain access to EGR system I've done some tests:-

i) removed hose to EGR valve, check MVB 03 so can see go out of spec wildly and correct spec once vacuum restored and valve operating... by this test I gather EGR valve not staying open and is opening when needed...

ii) removed hose to EGR cooling flap, check MVB 03 so can see go out of spec with very small amount and correct once vacuum restored, reasoning why it is going out of spec at idle is due to how cooler restrict EGR flow and at idle cooling flap correct default is straight through...

Now I'm thinking a 046 905 291 A Vacuum check valve@£13 must be tried?

From what I've seen of your posts you have an A4 3.0 TDI... so did you change valve? what was your solution to fluctuating idle?

Thanks
G

[wjam]

In fact my problem was the fuel metering valve attached to the high pressure pump. But of course this is not available as a separate part. I refused to pay Audi price and found a distributor of bosch pumps.. Saved a lot of money, and get to keep the old pump (which is in fact OK).

The problem with the inlet flaps is unrelated, but Audi refused to fix only the fault I was complaining about and said it was their way or no way. They opened a case on my extended warranty, and left it open, which prevented me from taking the car to another dealer or mechanic under warranty. Nice chaps these Audi franchises.

So guess what. I chose my way. Buy pump from distributor and find friendly independent. Saved myself best part of 800 euros

good luck

wjam

[gupsterg]

Hi,

I've just taken off the hose from vacuum pump on engine going to the black end of check valve...

I think functioning correctly as when I blow air it does not allow pass through, when air is sucked it allow pass through...

Ah well my journey continues ... thanks for quick response ...

ATB
G

[wjam]

If you have Ross-tech's SW, monitor rail pressure versus requested pressure and also the fuel metering valve.

If you then happen to catch the event it becomes obvious what's happening if you plot it on excel. The Audi garage freaked out when I brought them a graph of this. They called me obstructive and abusive in writing.. And there was me thinking it was helpful to not waste time and money on both parts.

I since heard a rumour ( I stress only a rumour but I personally believe it) that Audi charge for a new pump but in fact use refurbished units. This was common practice in a high tech industrial equipment company I used to work for.. so I would not be surprised.

cheers

wjam

[gupsterg]

In fact my problem was the fuel metering valve attached to the high pressure pump. But of course this is not available as a separate part. I refused to pay Audi price and found a distributor of bosch pumps.. Saved a lot of money, and get to keep the old pump (which is in fact OK).

Hi wjam ...

Just like you I had not found this part available separately via parts dept or catalogue, so I thought why not web search the markings on N290 , which were:-

0 928 400 572
00874
58215

When googled the bold text a hit came up , 0 928 400 572 is Bosch part no for N290 and the hit in google showed that VAG P/N is 059 906 457 ...

I then had an ATP search with all brands/models carried out and hey presto part is available via VW dealer as it is available separately on a VW Crafter (2E) Approx. £150 inc vat , the fuel pump P/N that this is fitted to is 059 130 755 N ...

Not that I need valve I thought I would post if someone require it and dealer say not available ...

ATB
G

*** Edit ***

Bit more google reveals Bosch P/N 0 928 400 572 superseded/cross with 0 928 400 676

Link:- ZAWÓR REGULATOR CIŚNIENIA POMPY 3.0 TOUAREG (3315551677) - Allegro.pl - Więcej niż aukcje.
Link:- Ventileinheit, Common-Rail-System BOSCH 0928400676 | eBay- Bosch 0928400676 Metering Unit: Amazon.co.uk: Car & Motorbike
Link:- Elementy pompy Common Rail BOSCH 0 928 400 676 - Motointegrator.pl - sklep internetowy
Link:- 0 928 400 676, 0928400676 - YouTube

More googling found brand new one for £90 delivered to UK from DE ...

Link:- Ventileinheit, Common-Rail-System BOSCH 0928400676 | eBay