CIS Questions - Cold Starting Issues/O2 Sensor Issues
 

I started getting into my CIS problems. Here are the two problems thus far:

1. On warm to hot days (I guess above 50 deg.) on a cold start the idle will want to stall out. I'll have to hit the accellerator a few times to keep the idle up. When I do that I'll usually hear a pop from somewhere in the engine bay (I think). Once the car warms up, it is fine. On cold days this does not happen and it idles as it should on a cold start. Where should I start?

2. I went to check my O2 sensor system with a dwell meter today. Whenever I would hook up the dwell meter, the frequency valve would stop buzzing. So couldn't check if the system was functioning. Again, where should I start?

Matt,
Just a thought as I just went through something similar... pay special attention to Peter Zimmerman's reply on the link below.

http://forums.pelicanparts.com/porsche-911-technical-forum/509484-81-sc-oxygen-sensor-relay.html

Matt,

The first thing to do is never touch the throttle on a cold start, it only leans out the mixture and blows air boxes. An 83SC can be tuned to start and idle cold or hot with no throttle pedal. How are you trying to hook up the dwell meter ?

My advice would be to disconnect and plug both vacuum lines to the distributor, reset the idle to 950 rpm, and check the ignition timing. Then reconnect the vacuum advance and leave the retard disconnected. Try a few cold starts and see if your problem goes away. You really only get one chance a day, so it may take some time to find the best settings.

I don't press the throttle as it's starting. This is after it has started and is trying to idle. As the idle is dying, I hit the throttle to keep it from stalling. Bad? This does not happen very often it is intermittent.

Well, today I reset the idle to 950 rpm, checked the timing, disconnected the O2 sensor and set the CO level to about 3.4% +/-. The car ran nice after I did that. Seemed to have more low end power under 3,000 rpm. I don't know about the cold start yet because I haven't tried it with these settings. I would like to run the O2 sensor the way it was intended, but if you look at problem no. 2, I'm not sure if the system is working properly. Plus John Walker recommends this setting and I was curious to see how the car acted.

In regards to hooking up the dwell meter, I am connecting my green signal connection to the pin on the test port with the green/white wire. Then I ground the other connector to the engine (specifically one of the nuts that hold the coil pack to the fan shroud. This is where the original spark plug wire ground was connected, so I figured it is a good ground spot. Am I doing something wrong?

Bad?

Pedalling the throttle on a cold start is the route to a blown air box. The extra 5 degrees of timing should give a stronger cold idle. Maybe you are touching more than one pin in the test connector, clean off the green/white stripe pin and use an isulated terminal or alligator clip. Are you using an analog meter and what are you using for a power source ?

That's what I thought, so I made sure I was only making contact with that one pin. I'm using an analog meter. It only has two connections. The green for the signal and the black for the ground. There isn't a power connection. It's this one:

http://forums.pelicanparts.com/uploa...1259583592.jpg

However, I just looked at the manual. It looks like it shows hooking up the green wire only. Maybe I shouldn't be connecting the ground wire??

check the aux air regulator (AAR). it could be sticking. maybe the lower temps make it open like it should.

Have you ever used this meter before to measure dwell ?

No. I bought it specifically for this purpose.

have you had any good results with that dwell meter? I have the exact same one, and have not viewed the typical results that everyone says I should see with it....ie. dithering of the needle.

When everything's correct, the dithering of the needle is quite small with the engine at idle in closed-loop mode.

Brian