Re: Rough idle @ startup, only 1-2 sec.
This is my post from another thread.....
Dunno if this helps any of you, but the reason why I asked if you had just filled up with fuel is as follows - bear in mind, this is just a guess... the fuel system is a closed system, so what this means is that the vapour at the top of the fuel tank has to be burned off - the tank is domed so the fuel vapours can accumulate there, and these vapours are sucked off through a hole and hose at the top of this done, into carbon cannisters which are somewhere in the engine bay and the vapours are burnt off.
If you overfill the fuel tank, then what happens is this domed part of the tank fills up and instead of vapour it is filled with fuel, which is then sucked through into the carbon cannisters (this sucks the whole time it is running). When the carbon cannisters become logged with fuel, they are sending way too much fuel to where it shouldnt be and it affects the fuel mixtures, effectively flooding it - I think....
So, if you refuel, overfill and then only drive a couple of km home (ie not enough to remove/empty any fuel from the domed part of the tank), then the cannisters are becoming soaked on the way from the petrol station to your home, and because the tank is still over filled, the cannisters remain soaked until you next start it. It is kinda like flooding it. And it will continue to do this until the carbon cannisters dry out and begin sucking air for a while, again - which is why it will run rough, not start or stall in strange areas. It happened to me and I sort of eliminated it by trial and error and found that when I didnt fill it fully for a few weeks (this was about 6 months ago) I never had the problem again - so basically fill it to one click and leave it. And if you have to over fill it, make sure you are driving a reasonable distance before you stop it again....
Anyway, this might not apply to all or any of you - could be many things, but this is just something that seems to be quite common and also something that people don't think of... and if I have any of the mechanical details wrong, please correct me - I don't really claim to know anything....
rom another thread - dunno if this helps....
Also, have you considered an oxygen sensor problem - when it runs in lean mode, sometimes they run too lean and surge and jump around a bit - this can only be fixed by Ford reprogramming the computer settings....
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