Porsche Enthusiasts Club Forum

hi i'm a new member here bought a very needy 1991 s2 a couple of weeks ago

just a question to start off with ,what rpm should the car be at on a cold start as mine starts idles at around 1000 for a second or 2 then rises to nearly 2000 rpm until it begins to warm up then it eventually drops to about 900 rpm
is this normal or do I have a fault

Welcome. Idle should be 840rpm. Check out http://www.clarks-garage.com for diagnostics.

yeah Ive looked on there but it doesnt mention cold start idle ?

they have a tech section on the ICV but not the one for the s2
does my s2 have a aux air valve?
I dont think my s2 should rev to 2k when cold ,if I shut it down anywhere when warm and start it up again
the rpm is a little higher than normal then it settles down

mine idles at cold at approx 1000rpm and hot at 850/900 rpm.
check idle control valve is working ok.may need clean out can get stuck.

Nick

thanks mate ,its a little hard to get to but I think I can pull it out without having to take off the whole inlet manifold

I took the pipe from the throttle body to the idle control valve off this afternoon and sprayed in fuel system cleaner lots of black gunge came out ,I think I'm gonna have to take it off and clean it ,I tried the car again from cold it went to 2k rpm but when I squeezed the pipe i'd taken off the rpm dropped to about 1krpm ,so tomorrow I'm gonna take it off and follow the clarks guide to cleaning and testing it ! I'll probably end up cleaning all the pipes also lol

right I took off the idle control valve (without removing the manifold and it wasnt that hard really ) and gave it a clean ,checked its operation ,when no contacts it was open when introduced to a live feed it snapped shut immediatly

I cleaned everything up and checked everything I'd took off the afm was fairly clean but where it connects to the front rubber hose it has oxidised quite a bit i gave the rubber and afm a bit of a clean ,the hoses from the ICV were all clean ,I couldnt find any vacuum pipes that were damaged or disconnected ,I restarted it and it was exactly the same

started and ran at 1100 revs then the revs rise to 2000 and only settle down once the engines warm I unplugged the ICV and the engine died to 1000 revs at cold

any clues?

have you tested the DME temp sensor at the front of the block under the inlet manifold.Normally has a blue top .Unplug and see if it makes any difference when bridged across contacts. You can find a reference to testing fully on Clarks Garage website.
Good luck

Nick

I bought a new dme temp sensor ,design911 and porscheparts cost is around 44quid wilmslow OPC 24quid and 19quid of your a tipec or pcgb member

I thought since Its so cheap I'll just replace it

Replaced the dme temp sensor today then started it - it still went to 2000 rpm until warming up ! So it's not the idle control valve or the dme temp sensor

I quick recap on what happens I start her up and she idles at about 1000rpm then the revs rise to as much as 2200 rpm eventually drop to around 1400 but when the car gets properly warm she idles about 850rpm

my money is on an air leak. manifold gaskets might be worth a look because the manifold might expand when warm and close the gap.

Squirt some wd40 around while its exhibiting the problem and see if it picks up. Also air leaks can often be heard.