Fiesta auto cutting out.......AGAIN!

[mildwin]

Fiesta automatic 1.3 1994 was cutting out. Mechanic looked at it, was ok for a while. Today it did it again when stopping & slowing down. Motorway journey was nice and smooth but coming off and having to stop it cut out. Was serviced only last week so has new plugs, filters, oil, etc, passed its MOT last week too. Any ideas what could be causing the problem, its extremely frustrating as it does it for a while, then seems to be fixed, then for no reason starts doing it again. One of those annoying intermittent problems. Any suggestions would be appreciated, thanks.

[mildwin]

Forgot to say that when it is slowing down, before cutting out, its goes quite juddery.

[maxximus]

when you say cutting out do you mean quitting completely, but starts up on its own right away or do you have wait for a while. if starts right away could be EGR related, or if you have to wait could be something temperature related, just guessing though.

[JimmyK]

Here is an answer I posted last time. Did you look into this, or suggest it to your mechanic? The situation of it being OK for a while is EXACTLY how I said I found it.

On older Fiesta's, there is a device called an anti-dieseling valve. it cuts off the fuel supply when the ignition is switched off and stops the engine running on (like a diesel). I say older: mine is a Mark 3 1990 and it has one: the engine is called an HCS engine, they may be fitted on newer models, and other engine types too

I had a lot of hassle with one of these, until I found I had knocked the connector off the carburettor! it was a cylindrical push-on connector, went onto a connector on the carb which looks like a screw thread.

probably worth a look for a bit of wire that goes nowhere, hanging around somewhere near the engine (almost certainly in a place thats not obvious!)

I spent ages tinkering with the idle speed and mixture, it did run ok for some of the time after fiddling but after a while it would not idle (ie it would cut out when you take your foot off the accelerator)

good luck!
(that was the old response... read on!)

another thing to consider is a thing called a throttle kicker. it slightly increases the idle speed when in neutral, and is fitted only to automatics: I think the reason for that is that automatic gearboxes have a viscous drag which is not apparent on cars with a manual clutch.

[mildwin]

Thanks for that. I hadn't mentioned it to the mechanic but will do. It is extremely annoying as it is intermittent, will do it for days at a time then nothing for a couple of weeks.

With regards to it cutting out, it either tries to cut out, or it cuts out totally. Starts first time each time afterwards but at next junction does the same thing again.

Car was only serviced last week and passed its MOT so I know it is isn't anything too major but it is frustrating to say the least! People have suggested idle speed, air/fuel mixture and JimmyK thanks for your reply, will have to look into that. Fingers crossed

[JimmyK]

no problem, I hope you can get it resolved.

just to clarify on the throttle kicker, it increases the idle speed slightly when in drive (not neutral as I said) to compensate for the viscous drag. so if it idles OK when in park (when the gearbox is disengaged) but wont idle when in drive but with no accelerator pressed, that would be my first port of call.

once again, good luck!

[mildwin]

Thanks, not sure if that is what the mechanic altered originally, it was something on the automatic gearbox as the gear changes were 'erratic'. But yes, it does idle fine when in park or neutral, but as soon as it goes into drive you can hear the revs drop, and the car attempts to cut out. Once going it is ok, until I hit a red light, junction, etc. Be ok if I never had to stop!!

[JimmyK]

HI, well the mechanic fiddling with something on the gearbox doesn't sound right to me.

The throttle kicker should increase the idling speed when its in drive, and it sounds like thats not happening. I believe the mechanism includes a solenoid and some connection from that to the carburettor rather than something on the gearbox. I will look again into the details in the Haynes manual and get back to you.

[mildwin]

Me again! Mechanic came today & it appears to be the same thing causing the problem as before. It is something outside the gearbox, a throttle something or other. Last time he was able to just adjust it but this time it needs replacing. The problem occurred for him too & every time he attempted to put in drive or reverse the car cut out so he disconnected it & it was fine, so will need a new one. In the meantime he said I could drive it with it disconnected, as long as I do replace it shortly. So fingers crossed it is sorted just need to wait for the part. Thank you all, especially JimmyK.