Porsche Enthusiasts Club Forum

I have just brought my first 911 sfter 3 years of 944 bliss.

On start up the 911 is very irratic with revs fluctuating between 1500 and 500 and occasionally cuts out.

When the oil pressure is up it runs fine.

What is causing this? Warm up regulator?

also how long should it take for the oil pressure to maximise after start up?

it is a 1980 sc.

Any comments or help greatly appreciated.

Probably no use what so ever, I have looked at a few 911's before buying my first last week, mine has the same problem but I'm told it's a very common problem. I was told what did it but I can't remember now.

could be your CDI box on the way out.

it courses mixed electrical messages to the engine managment. so the car is "hunting" for the correct levels for the engine to work at.

these cars take a long while to get the oil up to working tempratures..be gentle with them for the first few miles. and also for the last mile or two if possable.

Whats a CDI box Helen? This the equivelent to the 944's DME????

just knew someone wasgoing to ask me that

umm its the thingy that controls the ougamaflip that tells the engine what to do



it's small silver electrical system control box thingymajig.( that costs way too much money.) and is the central (brain) electricle nervous system of the car.

errr Thanks Helen............

Capacative discharge ignition, CDI builds up power to send to the coil. unlikley to be this i think. it should make a high pitch whistling noise with the ignition on butnot running. 300 qiud second hand.

could be the idle control valve, the warm up regulator, just simple fuel pressure. bung a can of slick 50 through with about 10litres of fuel in the tank !


as for oil My SC goes straight to 4 bar oill from cold

had same sort of symptons on my 964 (those that came to wales might remember) and putting in a new CDI box completly cured the problem.



oil got up to working temp instantly on that car But on my 930 turbo it would take at least 3-4 miles before the car was up to real working temptrature.

Thank you

were do you suggest for the CDI.

Does anybody have a spare idle control valve, WUR or CDI for a 1980 SC that i could borrow to fault find before i start spend serious money.

Cheers

Ps i have just booked a stall at TIPEC 2008 so see you all there.

Does anybody know the next Ace cafe day so i can take the 911 out for a thrap.

Elliot
http://www.porkaparts.com

Suggest the idle control is checked first, but seriously consider a live re-map with Wayne at Chipsmasters.
Both my 911's had serious "hunting" for the first few minutes on start-up which were really annoying.

Both in the end were fully sorted. The first by replacement of the ECU chip (Steve Wong chip), and the second (current) Targa by a live remap (approx £350) So not really "serious" money, and my 3.2 went to 253bhp!

oh like the sound of that Rich. good advice

you wont be able to remap the sc there is nothing to remap !!!! the motronic on the 3.2 has a chip you can remap, but not the sc as it aint got any chips in, it has CIS for the injectors , cis
=continuous injection system, hence the backfire problems 1973- 1984 cars, pre 73 is MFI after 84 motronic

.the ignition is the cdi system and the coil dizzie etc, nowt complicated. leads have a habit of going .


dont replace the cdi if it is whistling cos it probably isnt the cause of the problem,
if you want to try my cdi and you are in bournemouth you are welcome !
CDI BOX


do bung the slick 50 through.


this prob imho is most liable to be fuelling. get it on a gas analyser if you can. As it may be a mixture prob which is a common cause of the hunting on start up

the idle reg is available from most anywhere as is most of the other stuff. Also consider your fuel pump and fuel pressures, perhaps even the fuel accumulator. so get the pressures tested.

helen your 964 didnt have a cdi box !!!!!!!!!!!!!!!! or at least i dont think it should have had! you had motronic which replaced the cis system so you had the chip etc which was an engine managment system

just realised that was a very technical post for me

Was just thinking that, you now need to lie down in a very darkened room!

worst thing is I think it is right as well, a double first