[xj] Rough idel question '86 US SIII

XJ
1

Greetings,

In exploring the ubiquitous rough idle in my SIII, with the engine
running I noticed that the rubber vacuum hose which runs from the
intake manifold up to the steel tube across the engine bay struts to
the cruise control bellows appeared odd. Squashed flat. I pulled the
rubber hose at the manifold end of the steel tube and my idle speed
increased and smoothed out. Re-attached the tube, idle slows and
roughens. Now, I understand that if the engine would like more air
and suddenly gets it, that there should be a change in engine speed,
but is the vacuum hose supposed to be sucked flat??

Regards,

Peter Morris
Vista, San Diego County
California
'86 Jaguar XJ6 SIII
'78 Fiat Spider
'93 Ford Escort
'72 Ford Ranchero
'98 Ford ZX2

2

Ours is not flat and works ok.

Alex
79xj6

Peter Morris wrote:>

Greetings,

In exploring the ubiquitous rough idle in my SIII, with the engine
running I noticed that the rubber vacuum hose which runs from the
intake manifold up to the steel tube across the engine bay struts to
the cruise control bellows appeared odd. Squashed flat. I pulled the
rubber hose at the manifold end of the steel tube and my idle speed
increased and smoothed out. Re-attached the tube, idle slows and
roughens. Now, I understand that if the engine would like more air
and suddenly gets it, that there should be a change in engine speed,
but is the vacuum hose supposed to be sucked flat??

Regards,

Peter Morris
Vista, San Diego County
California
'86 Jaguar XJ6 SIII
'78 Fiat Spider
'93 Ford Escort
'72 Ford Ranchero
'98 Ford ZX2