I've recently been plagued by a problem with my XF ghia.
What happens is, when I come to a stop (say at a redlight) it starts idling rough, almost like its hunting for the right idle level, and if I dont slightly use the acc. pedal, it will actually stall.
The mystery is, it only happens sometimes...it can be after a long drive, or just a short one or not at all.
It did have a full service just a month or two ago...
Sounds exactly like the problem with my XF Ghia - is your rough idle accompanied by a misfire/surge sort of effect below say 2500 rpm at WOT & a desire to stall when hot & you go from neutral to reverse or drive?. I've just replaced the gasket on the plenum & it's largely gone away - but it's far from perfect. It all feels very much like a vacuum leak.
In your case if you don't have the misfire/surge I guess it could also be related to the ISC valve - the one on the top of the rocker cover closest to the firewall. This regulates idle speed for different engine loads ie A/C. From my inspection of this valve it doesn't completely close off - just varies an open port. Try turning the A/C on & off & see what happens.
Apart from that gasket on Friday over the last few weeks I've done the following which had no effect: New coil - new cap - new rotor - new topgun leads - new plugs - the 2 other intake gaskets between the head/injector manifold (that ones PRICEY) & between the injector manifold/tubes - injectors serviced & cleaned (out of car - not just the waste of time in car flush).
I've heard the TFI modules on the distributor can give trouble - with intermittent faults or total failure. I don't know the symptoms of this exactly but it's the way they are made - the technology back then. There's a Bosch replacement & a Wells replacement. They're not too badly priced - $90 for the Wells - but I'm in communist NZ so it's probably cheaper under the capitalist Aussie system. An auto electrician should be able to test the aspects of that for you - I can't find one here who knows #@%! from chewed dates though......
Have you got a workshop manual? If you haven't & are considering getting one - DO NOT get the Gregorys one - it's crap. Tells you how to pull all the bits out etc. but not nearly enough info on how to test them once you've pulled them or on car. Contains crap you'd never want to do yourself like checking crank bearing clearance etc.
Anyway - hope something in there helps - post your success/failures - maybe we can get to the bottom of this.
Wow, widespread problem then.
Today is was pretty bad, motor actually stopped while I was still moving (albeit very slowly. still, coming up to a roundabout...)
And it only happens in gear, it idles fine...select a gear, bit of a shake...then it just stops.
It doesnt happen under throttle, but it does if the revs drop below 1000.
Anyways, I'm gonna have a good look at everything on the weekend and see if I can pinpoint whatever it is.
Thanks for the help guys, cause its givin me and my old man a few headaches.
Tomorrow I'm taking it to the local Ford lads (Dont worry, I do all their window tinting, so I get good prices and free help, just as well though!)
So hopefully tomorrow, I'll have it fixed or at least an answer.
Keep you posted!
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