Idling yo-yo and cut out

Just staring to think things were fine, most jobs done (just radiator to do) and a nice polish at the weekend, then today coming into work, idling is producing yo-yo revs. When I come to stop, the car stalls.

Happened a few weeks back and resetting throttle position sensor cured it , but this didn't work today.

TPS?, IACV,? something more sinister.........

Never rains...........(well actually it does...frequently)

broon wrote: Just staring to think things were fine, most jobs done (just radiator to do) and a nice polish at the weekend, then today coming into work, idling is producing yo-yo revs. When I come to stop, the car stalls.

Happened a few weeks back and resetting throttle position sensor cured it , but this didn't work today.

TPS?, IACV,? something more sinister.........

Never rains...........(well actually it does...frequently)

Iac valve is usually a good starting point. Pull the hose off and try squirting some carb cleaner into the valve.
I found you could do this via the access panel in the boot. If it improves, then you can get the old engine access panel off and do the job properly.

After cleaning and then replacing my IACV, I also found that the tickover adjustment was critical too, someone, could have been me, had altered the screw to try to remedy the yoyoing and this incorrect setting worked against the iacv causing the up and down effect.

I sorted this by, with a hot engine, watching the revs return to tickover.
I saw that the revs were dropping below 700 before returning to 850.
I gradually altered the screw until the revs returned smoothly to 850 without dipping below or hanging above. Reset the TPS after this and the revs have been almost perfectly behaved since!:yesnod:

thanks David. when I changed the 52mm TB the other month, I had adjusted the screw (due to problems cause my my idiocy)....maybe that's the cause!

got some time off later this week, so can have a play

Not had a chance to look into this yet, but on way home last night it was fine for half the journey (no stalling), then got steadily worse. resetting TPS didn't work and by the time I got home I had been stalling at every single roundabout, traffic light and junction...and there's a lot!

So, to cut a long story short, it seems to be made worse when the car has warmed up? Does this hint at something other than TPS/IACV? Fuelling? Or maybe a vacuum leak when rubber pipes are warm?

intake air temp sensor ??, inlet air temp sensor ??

petevick wrote: intake air temp sensor ??, inlet air temp sensor ??

Mmm....IIRC my F doesn't have the separate IAT sensor.

Cheers, Pete. will give all sensors a clean and see if it helps.

Should have a box of sensors from Maggie somewhere.....not that it would be too clever to install those based on her previous LOLnsor ??,

I've had an idling problem for a while, last weekend I fitted a new IACV, but still had a slight problem, so I then blasted the TPS as best I could with carb AND contact cleaner, and cleaned every multiplug I could lay my hands on.....so far *touches wood* it seems fine.

well I've just bought a 500ml can of carb cleaner so will find out tomorrow :lol:

Thanks again everyone!!!

Managed to do it by adjusting the screw although I did squirt some carb cleaner in the IACV pipe too, but I think it was sorted before I did that.

This forum is awesome!

No....You're awesome dude.