Classic Audi - View Single Post - Fuel system pressures

Duffy3074 · 29-10-20, 01:14 PM

Did a full cold to hot this morning

Ambient temp was 10 degrees

Cold start pressure was 1.4 bar 20 psi
Hot with vacuum was 4 bar 58-60 PSI
Hot without vacuum was 2.8 bar/40 PSI

So compared to Mike's rebuilt WUR it's all too high (which ties in with the emissions)

I didn't have a vacuum gauge but disconnected the vacuum line (which I blocked off obviously) for one of the readings and suddenly the car started to idle much more smoothly.

Steve at KMI had said that I should check that the WUR held vacuum and this would suggest to me that it doesn't albeit there's a possibility that the reduction in fuel pressure accounted for the better running

Interesting! Choice now is whether to DIY or not?

29-10-20, 01:14 PM	#7
Duffy3074 4 ring whore! Classic Audi Club Member Join Date: Aug 2015 Location: Dalgety Bay, Fife Posts: 2,078	Did a full cold to hot this morning Ambient temp was 10 degrees Cold start pressure was 1.4 bar 20 psi Hot with vacuum was 4 bar 58-60 PSI Hot without vacuum was 2.8 bar/40 PSI So compared to Mike's rebuilt WUR it's all too high (which ties in with the emissions) I didn't have a vacuum gauge but disconnected the vacuum line (which I blocked off obviously) for one of the readings and suddenly the car started to idle much more smoothly. Steve at KMI had said that I should check that the WUR held vacuum and this would suggest to me that it doesn't albeit there's a possibility that the reduction in fuel pressure accounted for the better running Interesting! Choice now is whether to DIY or not? Last edited by Duffy3074; 29-10-20 at 01:39 PM.