boxerfan

OK, it seems as though the control pressure is off and the car seems to lean out or get way too rich and then won't start (I need to check this theory with the O2 sensor readings). Since a WUR failure is rare I have another thought. What if clip for the height adjustment spring of the sensor plate fell off? The sensor plate stop position would rise pushing up the control plunger and making the system rich. As the motor warms the A/F is too rich and the car stalls. Since this problem appeared after I simply counted the turns to stop of the CO adjustment screw and then returned it to it's original position here is what I'm thinking. Please comment and let let me know if you think I am off base.

When the CO screw was tightened right up the position of the control plunger relative to the sensor plate is raised up. If the adjustment allows the control plunger to top out then the result will be to force the spring rest for the sensor plate downwards. Push it down far enough and the clip that adjusted to stop position of this spring will loosen and fall possibly fall off. What do you think?

Again, the symptoms are as follows. Car starts perfectly and idles well. After a 2-3 minute run time it will stall out. Keeping the motor above idle will prevent a stall. Once stalled and allowed to cool the car will start again right away. It is definitely CIS system related and not Crank/rpm etc etc.

Black-Wolf

if you have a mechanical part that fell out then all temps would be affected, especially something like that. I would HIGHLY suspect your o2 system is the problem. pull the o2 and clean it or replace it with one out of another car it sounds like the o2 is "stuck lean" a problem caused by carbon and crap plugging up the openings in the o2 sensor. the o2 sensor has no effect untill it gets warm 1-2 minutes after startup, the car then goes into closed loop and starts reading the 02 sensor. before that it uses a base mixture value set by the computer and ignores the o2 alltogether.

boxerfan

wouldn't the o2 cause problems at all rpm & load? This issue cropped up right after playing with the CO setting and that is also why I suspect the issue lies there somewhere. The part in question would only affect the idle. Once air starts to pass over the sensor plate the fuel and air mixture will once again equalize the A/F to appropriate ratios.

Good explanation of the O2 functionality.

Black-Wolf

you can reset the screw to factory settings with a dwell meter<ul><li><a href="http://www.sjmautotechnik.com/trouble_shooting/injector.html#mixture">http://www.sjmautotechnik.com/trouble_shooting/injector.html#mixture</a></li></ul>

boxerfan

I just can't screw up enough energy to wrestle the air filter out and reach in to see if that clip fell off.

I do not have a dwell meter but I am secure in the fact that I counted correctly when the adjustments were made so the CO should be alright.

If you have the book: "How to tune and modify Bosch fuel injection" by Ben Watson have a look at page 111. It shows the clip I am talking about.

I'll let you all know if that was it once I get in there... in the daylight... without sleet.