Anti shudder valve.. wotsit?

[allypug]

Was wondering when this valve is used, and where it is? My AMF engine shudders like hell on startup, and a bit when shutting off. Is this the cause? and where is this valve?
My car still goes into limp home mode on most trips, checked all vacuum hoses and nothing to report there. Did start behaving once I had anchored the maf sensor to its engine bay mounting point rather than having the pipework flapping around. Could this valve have anything to do with that?

Steve T

 

[Weetank2]

Any dash warning lights in limp mode?
Injector wiring loom possibly degraded, turning off and restarting will clear it for a while
Anti shudder valve is to control shut down my understanding

 

[allypug]

No warning lights, the limp mode thing has only happened since the headgasket was changed.. so they would have taken the injector harness off when the head was skimmed.. so could be a possibility

 

[Guest 4123]

The anti-shudder valve is part of the EGR valve; it is the butterfly flap which should close on switching the ignition off. I have recently changed the EGR on my 1.2 because the diaphragm for the butterfly had perforated. You can test for diaphragm leaks by attaching a piece of tubing and sucking on it; if there is no resistance there is a leak. That being the case, it might be that the vacuum pump cannot compensate for the leak, giving rise to other vacuum problems. However, this shouldn't apply to the anti-shudder valve as it is only exposed to vacuum on switching off the ignition.

RAB