fiesta auto cutting out update........AAARRRGGGHHH!!!

[mildwin]

Where do I start? Fiesta auto 1994, 1.3 Ghia, was cutting out when slowing down & stopping. mechanic came, disconnected part said could drive till got new part. Was ok for nearly 2 weeks, then started to have erratic idling, go up to about 1100 then quickly dip to 300, then back up, down, etc. Mechanic came again, fitted new part was ok for him & for a short drive I took it on. But today it is 'lumpy' (for want of a better word), on acceleration and once again the infamous wanting to cut out when slowing down showed its ugly head!! Help I am getting very frustrated with the car. Thankfully it hasn't cost me very much financially (very good mechanic) but I am pulling my hair out now. I thought with the new part it would be fine but it isn't, could it be that it wasn't that part it needed? What else could cause these sorts of problems? (part was called a throttle something, sorry can't be more specific, but apparantly it sends messages to the engine management system). But part has been replaced and car still not wanting to play!!

Would really appreciate any ideas. Mechanic will be called again, so any ideas I will suggest to him. Thank you

[mildwin]

The part was a throttle potentiometer, I just remembered what the mechanic called it! Oh, & it was a second hand part, would I be that unlucky to get a dodgy one to replace the existing dodgy one??

[JimmyK]

Hi there, just looked at the old post and as you werent adding more thought it was fixed!
I am assuming he replaced the throttle kicker, but I don't think it sends messages to the ECU, its on the carb and does an idle speed adjustment there. however Mr. Haynes shows an electrical device somewhere in this throttle kicker system which I havent figured out yet.
Could also try the anti-dieseling theory, which cuts off fuel when the ignition is switched off: mine was disconnected and I could get the engine to idle by tweaking mixture and the mechanical idling adjustment, but after a while it would keep stalling. look at the old post for more info on this.

[JimmyK]

hi mild, didnt see you had posted a reply about the throttle potentiometer, I will have a look again the the haynes manual, it could be your car is newer than my book covers. back next week!

[JimmyK]

hi there, I had a look at the haynes manual and its confusing (but they are not renowned for their perfection!)

I have worked out that there is a solenoid on the engine bulkhead, next to the ignition unit (ESC, or ESCU). when you put it into gear, the gear selector closes a switch, which operates the solenoid electrically.

the solenoid has two tubes going to it: one to the inlet manifold, the other one to the carb. when the solenoid is operated, it connects the two pipes together, so causes the inlet manifold vacuum to operate a device on the carb, which increases the idling speed.

I am pretty happy thats how it works, but the confusion is that the haynes manual wiring diagram shows an electrical connection to the carb, not the pneumatic (vacuum) one it shows elsewhere in several places! I think its this diagram thats wrong, not the other bits, for which there are photos.

I am concerned tho about your mechanic. there is no such thing as a throtle potentiometer, as far as I can tell. also he said there was a connection from the device he replaced to the ESC/ESCU: the connection is directly from a switch operated by the gear selector, the same switch that operates the solenoid, so unless he has replaced something inside the car I am sceptical.

I think on balance I would be looking around for another mechanic! where do you live? I might be able to help you out.

[mildwin]

Thanks, but I am quite happy with the mechanic. He was recommended by a friend and when I put it in for its MOT the garage asked me who usually looks at my car & did the recent service. i told him & his reply was "don't ever go anywhere else, he is very good. Whoops, maybe I shouldn't have said that" He was singing his praise and that is coming from a garage in competition!
Maybe it is my explanation of things, I don't know anything about cars so when he tells me things it goes over my head. But he definitely said the potentiometer, which I think he said sends messages to the engine management system.
Oh, car has been fine this week, not cutting out or anything. Maybe it is, at last, sorted?? Watch this space

[JimmyK]

Then you are welcome to stick with him, and keep having him come back, and keep having the car stall, and keep getting infuriated with it.

There is a saying my friend has: keep doing what you are doing, get what you always got.

[mildwin]

Hi, the car has been fine this week, had the 'blip' the day after mechanic fitted new part but fingers crossed it has been ok. He called it a potentiometer, which I actually watched him replace, in the engine, looked like some sort of switch, leads at both ends. He also plugged it into some little gadget to check something, voltage maybe? The numbers were going up then very quickly dipping out to much lower numbers. As I said he did explain it all to me but I am not at all interested in cars so most of it just went over my head. He has been very good. I have asked a number of people who know about cars & they have all said that the intermittent problems are the most frustrating, and that cars cutting out when slowing down can be caused by a number of things.
But as I said it has been fine all week, not cutting out, idling fine so hopefully the new part has done the job. Fingers crossed and thank you JimmyK