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Poor cold running

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I've done a search and haven't found anything that is similar, but I seem to be having an intermittent problem when the car is run from cold. Every now and then, when the car is first driven after being parked for a while (day or more) it will idle very roughly and sometimes stall when pulling away of not given a big handful of revs. It also feels quite sluggish to drive. After about 10 minutes, once the car is fully warmed up, its fine, idles as it should and drives without problem.

I recently had problems with the temp switch on the rad, the low-speed fan wasn't switching off, and although I bought a new switch I haven't put it in yet as the problem seemed to go away by itself. So as a result of this, my theory is if the ECU uses this to also control the cold-start mode, then could the temp switch problems also be confusing the car into not going into cold-start mode? If the temp switch doesn't have any input on that, what else might be causeing the problems?

Thanks in advance for any help!
 
I believe there is a seperate cold start sensor on the cylinder head. IIRC there are two sensors towards the front, one for the temp guage and one to control cold start enrichment.
Tony
 
could be. I was always under the impression that the temperature sensor for things like that were from the sensor in the head though. I'm not sure though.

How does it idle on first startup? (before you've driven it)

I'm guessing that it's somthing ISV related. Certainly on mine with the ISV deleted, the cold idle is a real pig. But I live with it in the knowledge that once it's warm, there's one less thing to go wrong!

If you can, take off the hose to the ISV, and give it a squirt of carb cleaner. If it makes things better, then it probably is the ISV gunked up. I'm afraid you'll have to have it off to sort it properly though.
 
Ah, yeah I thought there would probably be a different sensor for the cold-start enrichement, as the rad temp wouldn't be the logical point of reference for such.

As for start-up idle, it's pretty rough. A good blip on the throttle seems to clear it temporarily but generally it will continue like this until the engine is fully up to temp.

I'll try the ISV trick, see if it helps, but where abouts does that live (still need to order a Haynes manual...)?

 
I'm not 100% sure on a lux, but I guess it's under the inlet manifold. It's a metal pipe looking thing, about 1-1/2" diameter, 4" long, has two pipes off one end, and an electrical connection off the other.
 
Thanks, searching threw up that location on an S2, but I would expect there would be a good place to start looking on my Lux.

Cheers for the help, will give it a clean tomorrow.
 
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