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Lumpy idle cuts out when hot?

L

Lance

New member
My 944s runs beautifully BUT sometimes the idle is lumpy and on occasions cuts out when at a junction, always starts first time after cutting out no problem when cold BUT bit lumpy on first start then ok for a good 10miles then starts to go lumpy...any ideas, I'm new to ownership, love the car should have bought one a long time ago! Any help great fully received thanks
 
I think ignition coil gives these symptoms.

Check throttle position switch is correctly rotated so that it brings the idle stability valve into play when idling.
 
Throttle Position Switch will give a slight "click" just as the throttle is being lifted away from the stop, check under the bonnet by rotating the the throttle flap by hand, the "click" is fairly inaudible so listen carefully.
As previously posted it could be the coil or the idle control valve which is a pig to get at [:(]
 

ORIGINAL: Paul 290T

I think ignition coil gives these symptoms.
Click to expand...

From my experience, ignition coil on the way out will usually fail when hot and will not work again until its cooled off. Because you are able to immediately restart after a cutout I would think Idle Stabilization Valve is more likely the culprit. Cold start brings in more air and a slightly richer mixture so the engine will run properly until its warmed up - after that its the idle stabilizer is doing the work. You don't mention any rough running off idle so I'd be looking at the stabilizer.
 
Thanks for advice, not been able to check yet! It runs perfect off idle and doesn't always cut out but revs drop right off when I stop at a junction sometimes it picks up other times it cuts out otherwise car runs like a dream
 
Yes - under the inlet manifold VERY fiddly to get at, but just about possible.

Could also be fuel pressure regulator
 
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