Missing

[Dezzy]

On my way home Thursday and i felt what was like a slight missing like on one cylinder, it got worse and after about 100 miles was quite bad but seemingly worse after lifting off the throttle and putting back on. I got to within 30 miles of home and the whole car was shuddering like I was down to 5 or something. It cut out and wouldn’t restart.
No faults recorded not even a misfire. But while trying to restart it threw a code about idle control valve so I reset it and still nothing. Called the AA and it did restart but very lumpy and popping back through the air box, the only way I can explain it is it sounded like a badly tuned carb’d car I’ve not heard an injected car sound like it almost like it was flooding. It did clear and we couldn’t get it to replicate the problem. Plugged into his Snap-On tool or my Vagcom there are no faults recorded. Car was fine all the way home. Fired it up yesterday morning and I cut out in front the house, restarted straight away.
I took the idle valve off and gave it a good clean and the MAF too Ranj came round while it was going back together and we went for a little run it was not missing at all although was a little hesitant a couple of times through the rev range.
Obviously I’m stuck without a fault and for it to cut out and not register one I’m stuckerer. Are there any live readings I can take that could pinpoint what could be happening to the old girl?

[Dezzy]

Also forgot to say while we had it plugged in yesterday after putting it back together it would read Idle and Part throttle only even when throttle was fully open.

[Architex_mA8tey]

sounds like a faulty idle control valve as per the scan Dezzy

The Idle control Valve (basically) controls the amount of air let into the inlet manifold when on idle. The valve has a 'Pin' which moves in and out incredibly fast, meaning the engine idle can be controlled accurately.

Common symptoms of a faulty Idle Air control Valve (IAC) are:
Poor idling (you would never have guesed!)
Cutting out when the engine speed drops (approaching bends, roundabouts etc)
High revving on idle
Idle speed going up and down

A diagnostic machine will sometimes point out the IAC is faulty, however, not always.

Sounds like it might be sticking even after youve cleaned it

[Dezzy]

Thanks Neil

She's let me down again, won't restart and has been abandoned out on a little village in the sticks.

Same again missing popping and then won't run. Seemingly when up to temp no issues when it was cold or warming and again no faults recorded. Could the idle valve cause this when not at idle?
Just would not run on any throttle position.

How long after an AA call out should you leave it before having a car fire?

[ainarssems]

Idle control valve would only affect idle/low throttle. Possibly crank position/speed sensor.

[Dezzy]

Thanks Ainars.

She totally refused to fire up yesterday, but i couldn't start top strip it down where it's dumped.

I wondering if it's fuel related, pump maybe

[graynada]

I must admit pump crossed my mind. I don't think i had any fault codes when mine went. Try running a feed direct (fused of course ) direct to the pump to see if you can hear it running.

[Dezzy]

Would the position sensor/speed sensor throw a code? I'm happier in a way that she won't run now as it should be easier to find the fault (fingers crossed) that said i'm still open to hear other reasons to non starting.

[47p2]

Crank position sensors usually fail when hot, so in theory it would start when cold even if it was faulty.