Well today has been an interesting day to say the least. Booked the weekend off work to go and visit my mum for her birthday this weekend. Anyway had ordered some new wheels in which a recirc valve was included in the price, was meant to arrive on Tuesday or Wednesday (at the latest) however they hadn't arrived by the time I left so off I go. I got a couple of miles and the car was running very very rough, sounded like misfires and nearly cutting out, the engine warning light came on and engine was idling erratically between 1000 and 2500 RPM. Pulled over, took a look at engine, couldn't see anything obvious so shut the engine off, left it for a couple of minutes and re-started and all seemed fine. However 2 minutes up the road it started again, turned around and headed for Richard Henry in the hope it would be a quick fix. They put the diagnosis machine on it and it threw up a idle valve issue (I believe) and they had a look. Said that the dump valve was to blame as the diaphragm was gone. What could cause this?

I took the dump valve off earlier this week just to check that the bolts would come off and put it straight back on. Could I have somehow caused this? Hopefully the recirc will arrive tomorrow and that will fix the issue.

Although the company sent the wheels via UPS and the recirc via royal mail, odd but should be ok. Hopefully this run of bad luck will end soon and stuff will stop breaking and I can have a cheapish week or two!!!

Any leak in the vacuum system could cause running/ idle issues .same with the air intake pipe work As the map sensor (on the inlet manifold) and the maff would get conflicting readings , so the ecu would try to compensate by adjusting the fueling and timing .

I understand all that, and understand why. More interested in what could cause the damage to the Dump Valve, RH said it was a Forge dump valve. Are they known to break a lot?

I got a forge one mate had a few vacuum issues it likes every pipe to be perfect

RH said the diaphragm was gone which would explain that. Is it possible to fix them?

Can buy replacements within a service kit I think

Sorry pommy i mis read the op i thought you'd asked ,could a leaky dump valve cause your symptoms .

I had a few diaphragm dump valves and blew the guts out of them a few times (wear n tear ) just fitted a new diaphragms untill bought a piston type which was much stronger

If the diaphragm is gone it will be a leak in the intake air , so the new recirc should solve it , but I'd check your vacuum as well while doing the switch ;-)

No problem mate, thanks for clearing it up. I will definitely have a closer look when I get the new part. However everything else looked as it should when I looked yesterday.