EGR Cooler Problem

[snapdragon]

Thanks again Lee - looks a great bit of kit.

Only the EGR and cooler bypass flap are vacuum powered. The turbo VNT, intake flaps and throttle are all electric.
On 2008- models with 4 digit engine codes such as CABA, the EGR is also electric but the cooler bypass flap is still vacuum on those too.

I need to get one of those handy vac pumps - but in the meantime I found the one way checkvalve 046905291A allows air to suck and blow both ways I cleaned it out with IPA and some blackness came out but it is still not sealing inside so will order a new one.
I pulled a vacuum on the rest of the system with my oil extractor and it held pretty well but not perfect. It got dark but tomorrow I will pull a vacuum just on the cooler and watch the arm move and do the same on the EGR and see if I hear it snap shut when I pull the pipe off. It will be better when I get a handyvac with a guage.

Interestingly, with the vacuum blanked off after the brakes, I still don't get an engine light until part way through the second journey and the VCDS readings are the same EGR actual is greater than specified even though I know the EGR is shut tight and has a stiff return spring.
I have read in an SSP PDF that EGR flow is measured by lambda changes and only uses a drop in MAF reading as a fallback. My lambdas are always pegged at 99.9% as though they have been 'fixed' at that by ECU software that the previous owner did which may not help, but I had the car over 4 years before I got issues with EGR so I know it isn't the root cause.