Idle_Off-idle problem

["Dave Swingle" <dswingle@xxxx>]

I was helping out another DMLer yesterday with a problem that has me
scratching my head a little. The original complaint was that the car will
either idle at 850 rpm (normal) or, as you tip-in the throttle, jump
immediately to about 1200+. Makes it hard to make a smooth start in a
manual-trans car. The odd thing is that if you take it out of "idle" mode by
backing off the microswitch adjustment, it will go to 1200rpm with the
throttle still closed. We backed off the throttle stop screw as well, no
difference. No one has ever messed with the A/F adjustment (it is still
sealed, the car only has about 3K miles on it). No obvious vacuum leaks.
Other than this, the car runs beautifully.

Other things to consider - this is a 3000-mile car, fuel system has
apparently had typical issues evidenced by recent fuel pump and lack of most
of the fuel intake system but seems OK now as long as the gas tank is over
1/2 full. Inside of the tank is clean.

So - it seems that the idle control motor is doing its thing, but it seems
odd that taking it out of idle mode increases the idle speed this much. I
tried the same thing on my car, opening the idle microswitch takes the idle
speed from about 850 to about 950 rpm. This seems normal.

What else should we be looking for?