Zetec slow running / idle issues - reposted from the DOC forum

[Adrian Southgate]

Hi all, I'm having trouble with my zetec randomly cutting out while driving. I think I have narrowed it down to the idle control valve but am having trouble verifying it before purchasing a replacement. 
It has happened about 6 times now, usually after I have come off the throttle and slowed into a village, I press the pedal again to pick up speed and the engine doesn't respond, just stops. (Once it cut in and out for half a mile before giving up) 
The engine then cranks when I go to restart it, maybe catches for a second and dies again. After that it just spins with no bang, there is however a strong smell of fuel so I presume the injectors are still firing. 
I have changed the crank and camshaft sensors, cleaned the idle valve, cleaned the maf, checked for vacuum leaks, and checked all of the loom for bad connections. 
On the most recent occasion it did its usual off throttle switch off, it did restart, but as soon as i touched the throttle it died again. As I had been suspicious of the idle valve so took the solenoid part off and held the valve pin in the partially open position. The engine fired immediately, so I used a rubber glove to hold the valve open slightly which had the engine idling at 5000rpm (after half an hour of standing in the cold irritating the locals with the occasional rev). With this I was able to get the car home 'idling' at 50mph. 
The question is whether it's likely to be the idle valve solenoid that is intermittently failing and whether when they fail they might cause the lurching as the engine cuts in and out? 
I'm really hoping that there is a zetec guru out there who may know or have experience of this happening elsewhere as it's getting a bit embarrassing now!

[Brian (up north) Morris]

faulty maf imho. had it on a mondeo. (hate new cars)

[Paul Sheridan]

Idle control valve, mass air flow sensor, air temperature sensor, water temperature sensor.  Any of these could be the culprit. Presumably its in a Dutton, and has been running ok! 

[James Doulton]

I am not sure why the car would not start but would provide petrol. The only explanation that I can think of is a defective ignition pack. Maybe it gives up when it gets hot. That would not explain the 'cure' of jamming the idle control valve open though.

I think that the best bet is to get the ECU codes read. He might be able to get a reader and do it himself or maybe a local garage could do it for him for a modest fee. Once the ECU has detected a problem then it will go into an error management mode which will depend on the error it has detected. But the ECU should remember the error codes and diagnosis should be straight forward.

My daughter's Ka suffered from a sticking idle control valve. The symptoms were that it was slow to respond when the engine slowed down and it would often stall but happily restart. I cleaned it with petrol and a small paint brush and it worked fine for a month or so before the symptoms returned. I'm guessing that the sticking was caused by oil from the crankcase breather as a result of its high mileage.

[James Doulton]

If the MAF is a hot wire sensor then you have to be very careful when cleaning it, you can't just use petrol because it leaves a film which attracts dust and dirt. I think that there are special cleaning sprays. Maybe if our friend cleaned the MAF wrongly then it might have caused further problems with a different modus operandi to add to the original problem.

[Brian (up north) Morris]

thats right james. i used a electrical circuit board cleaner. contains isopropanol . drys leaving no residue 

[Steve Kerswell]

asked the question on another site and got this reply from their expert : They do sieze up. Often in the closed position so they won't idle. You can keep them running on the throttle. So yes coming to a junction they will cut out with one foot on the clutch and one on the brake.

Is it an early escort alloy manifold or the later Mondeo plastic manifold. The latter valves aren't dear for the sake of a few quid I would give it a try.

[Steve Kerswell]

Just been informed of a fuel filter problem, seems the replacements are pants !

[Aidan Flack]

Thanks for copying this across for me Adrian, and for all the suggestions. I have checked the operation of the idle solenoid with a 9v battery and it seemed OK. I will replace it though to take it out of the equation as it is definitely failing to operate for one reason or another. If it's not that then it would be the signal dropping out for some reason, from research (and everyone's responses) I'll move onto tracing voltage on the wires, and then the other sensors.
I'll update once I've hopefully solved it. Would be so much easier if it wasn't intermittent!

[Adrian Southgate]

You're more than welcome. I know we have zetec users on here so it seemed logical. Glad you're here to take over though.