CIS

I cleaned airbox of dust, and cleaned sensor plate with carb cleaner spray and a lint free cloth. Put on stock air filter and gas filter. Now the 80SC doesn't run quite right. It hunts between 1000-1600 rpm when warm, but not warmed up, then hunts a lot less between 1000-1200 when warm, finally settling to an idle after being run 30 miles or so. I have ignored, for a few days, hoping it would fix itself. When I checked the oil, loss of vacuum caused immediate stalling. I have checked all vacuum connections. All vacuum lines are new. How do I check oil without growing a third hand?

Check the position of the sensor plate. You may have moved it inadvertently when you were cleaning it. It should be centered and not bind or hit the sides of the housing when it moves. You can center it by loosening the center bolt and adjusting it until you can get a 0.1mm feeler gauge evenly all around it.

Hope this helps.
Nick.

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Nick Shumaker
1982 911SC Coupe
nickshu@yahoo.com
PCA -- Rocky Mtn. Region

It's also possible that cleaning the sensor plate and the funnel will cause the mixture to be leaner than before. This would explain the stalling when you checked the oil.

Was there very much gunk on the sensor plate and funnel?

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Bill Krause
'79 911SC Euro

Sensor Plate was clean. It had been cleaned 5 mos ago after an oil overfilling incident.

If it worked fine before, but now does not, it can only be the misplacement of the air filter onto the airbox base proper...I'd reset the airbox cover and filter and try again.

Failing this, you must have moved the sensor plate somehow. Or, whatever you put into the sensor plate must have mucked up the throttle plate (butterfly). I would remove the airbox-to-throttle valve rubber cover (two bands) and look in there. This would also let you view the sensor plate from the topside, so that you can shine a light up from the underside and see the placement (centeredness) of the plate itself.

Jw

have you checked the basics? w/oxy. sensor unplugged, set CO to 3.5% on a exhaust gas analyzer, timing at 35 degrees at full advance, and idle set to 950-1000 rpm. leave the sensor plug off for best running. cleaning the sensor plate would not change it's position. they're not that delicate. did you get the boot clamps back on correctly? poss. air leak around clamp?

[This message has been edited by john walker's workshop (edited 04-13-2001).]