danny993

Very consistently, I experience a surging idle on cold start up in the morning. It does not seem to recur during the day. The surging is very noticeable (maybe 200 rpm) and lasts 3-5 seconds only.

Is this anything to be concerned about, and does anyone know what could be causing it?

uptheorg

I have this "problem", too, but do not see any smoke. It is more pronounced in cold weather. Would be interested in any ideas, or if it is just "normal". Engine has 70,000 on it.

JPS

My understanding is it is more or less normal. If it seems bad, you can clean the ISV (idle stabilizer valve) REALLY easy DIY with instructions on www.p-car.com. It gets a bit gummed up from time to time. I cleaned mine, and it made a little difference.

manek

My garage assured me this was normal behavour when I queried it.

95993RS

I too have this "problem" what is interesting is if you look at who has responded to this it appears to be related to 95' M.Y. only....
Just an observation

MikeAlwaysWins

This happened on my '95, but only once. I also remember it happening on my '79SC a couple of times... I chalked it up to "Porsche idiosynchroscity"..whatever that is....

JasonF

My '95 will periodically "hunt revs" upon startup when it's a little chilly out too. It really doesn't concern me for an otherwise strong-starting engine.

danny993

Thanks for all the responses. I also asked a service adviser at a dealer, and he said it was "normal", and not to be concerned.

Chris L

My '95 does that too. It's usually in a semi-heated garage, but when it's been out in the cold it's idle will cycle up and down when it's first started. I always thought that was normal.

Chris.

ddd910

I have the same exact problem on my 98' C2S, very rough idel every morning, the car did stalled 2-3 times in the past year. My dealer checked the car twice and the only thing they did was they added 2 bottles of fuel cleaners, didn't help much.... I remembered a technician mention something about the fuel line and fuel pressure regulator, but then he said it was no big deal. I didn't bother to look more into it up since my warranty expired already...

kkim

ddd910- you should try the ISV valve cleaning mentioned above. You'd be surprised how gunked up those things can get, which can greatly affect the car's idling.

JohnJL

I have this symptom too and mentioned it to Steve tonight. He suggested the O2 Sensor. Anyone else notice it and find a cure?

Thanks

JasonAndreas

Its definitely not your O2 sensors, those are ignored for about 1 minute until they are warmed up if the engine is stone cold. More than likely its just the cold-start enrichment function of the DME (controlled by your cylinder head temperature sensor) and perfectly normal. A gunky, slightly sticking ISV would probably make the situation a little worse.