Starting problems when cold

[dberman]

I have a 83 911SC. The car starts up immediately but the revs are low and sometimes it stalls within the first minute or so. Once it sits in my driveway and warms up for a few minutes it runs fine. Once it is warm and I turn it off and start it back up again, it runs fine. So, it seems like it is a problem only when the engine is cold.

I just got the car a couple of weeks ago so I don't have any past history to go on.

Can anyone point me where to look?

Thanks

Dave

[scarceller]

Check cold control pressure on the CIS system, could be a bad Warm-up regulator.

[Gemballa2006]

I have the same issue on my 86 coupe, I assume it it is the DME relay going but since you don't have that in yours I will be interested to see what you find. If anyone has any thoughts on mine that would be great too.

[ossiblue]

Welcome to the forum, you will find nearly all you need by asking. Yes, your warm up regulator is the likely culprit, but you need to check the fuel pressures of the entire system--a very easy task with a set of gauges. There is so much here about your situation, I would rather refer you to some original sources.

At the top of the Technical Forum page, on the right side, is a search button titled, "search this forum." Click on it and a box will appear. Click on "Advanced search." When the next screen appears, type somethink like, "cold start problem" in the seach box and click. You will then have lists of tons of past threads about your exact problem, plus information about your CIS system. This should get you started. Even if others reply with specific thread links (and they will) or specific remedies (and they will,) using the seach button is always going to be of help.

Again, welcome and post some pictures of your new car--we never get tired of seeing new rides!

P.S. Here's some light reading to get you started:
http://members.rennlist.com/jimwms/CIS/CIShome.html

[scarceller]

Originally Posted by Gemballa2006

I have the same issue on my 86 coupe, I assume it it is the DME relay going but since you don't have that in yours I will be interested to see what you find. If anyone has any thoughts on mine that would be great too.

The 84-89 cars are very different than the CIS cars. For the 84-89 cars a likely cause for cold start issues is the CylHeadTemp sensor. These sensors come in 2 styles - the older sensor is one wire and gets it's ground from the threads in the sensor. The newer sensor is preferred as it is 2 wire sensor with a dedicated ground wire. If you have the older CHT sensor get the newer one. You can test the sensor's resistance when cold and then fully warm to be sure it's not faulty. Here are the specs for the test:
Temp F / ohms
32F = 4000 ohms
68F = 2500 ohms
100F = 1100 ohms
212F = 185 ohms
300F = 110 ohms
340F = 80 ohms

With engine fully warm after normal driving the CHT should be 300-340F and the sensor should read 80-100 ohms.
At room temp (68F) the sensor should read 2500 ohms.

You can simply unplug the sensor from the harness and test it's resistance for given engine temps. I suggest testing the sensor before starting the car with engine dead cold and air temps around 68F.

Then drive the car get it fully warm, stop the engine and test again with CHTs in the 300-340F range.

A faulty CHT sensor is often related with cold start issues.

Please further describe your cold start issue / symptoms.

[brads911sc]

Welcome Dave. I suspect I have the same issue on my 83 SC. Same symptom... I had planned on tackling it.. I let you know what i find.

Thanks

[80-911SC]

i haven't read the manual on your year , but i think the drive way warm up is not recommended for your car. you should (i believe) start and drive gently keeping the rpm's down until it comes up to operating temp and the thermostat opens... .