1979 cadillac eldorado idle adjust

[Spazz99]

Hello got yet again another issue to cross off the list. I have a 1979 cadillac eldorado with the eltronic fuel injection system. Can anyone here tell me how to adjust the idle. Even after driving it for a while the idle still stays very high. Is there a screw like on carbs to adjust the idle, or is there a sensor that could be cooked?

[bcroe]

I have a 1979 cadillac eldorado with the eltronic fuel injection system. Can anyone here tell me how to adjust the idle. Even after driving it for a while the idle still stays very high. Is there a screw like on carbs to adjust the idle, or is there a sensor that could be cooked? 

Under the air cleaner, on top of the throttle body, is a black plastic "cold idle air valve" with a couple
wires attached.  It allows extra air when the engine is cold.  As it warms up, 12V power (from the fuel
pump circuit) warms the valve, and a brass rod pushes out to close the valve.  It is quite common for
the valve not to completely close.  Push down on the valve; if the engine slows down, the valve wasn't
closed. 

Cleaning the assembly might help.  Be very careful not to break off the tiny arm to the micro switch,
or the closing will take a lot longer.  One way to help is shim the valve with a spacer (sort of like a
dime) so the rod pushes it farther down.  Bruce Roe

[Spazz99]

That leads me to believe that component is fubared. Its already shimmed to the point were getting it in and out of the trottle body is quite difficult. So i guess thats next on the parts list.

[bcroe]

That leads me to believe that component is fubared. Its already shimmed to the point were getting
it in and out of the trottle body is quite difficult. So i guess thats next on the parts list. 

Could be.  Do make sure, 12V is applied to it whenever the engine is running.  Its wired to the same
circuit (inside the ECU) as the fuel pump.  Bruce Roe

[TMoore - NTCLC]

If the fast-idle valve has already been shimmed, and the idle is still too high, then you do you the air adjustment screw that might help - this spring-tensioned screw is located on the back of the throttle body (between the vacuum ports) - it is possible this has been adjusted - ease it in a little bit, and see if that makes a difference.

These cars can also idle fast if your fuel pressure regulator is malfunctioning, or if it is not getting proper vac. - check for any vac. leaks to make sure all is in order.

[bcroe]

The idle air screw will certainly make a difference, but I always say fix the valve first.  Otherwise the
idle could be different every day. 

Shifting topic, those valves have a tiny arm to the micro switch, which loves to get broken off.  Then
the valcve take a lot longer to operate.  I think I have figured a way to restore approximate original
operation even with the arm gone; adjustable even.  Basically I'd take the power to the valve and
boost the voltage with a tiny step up converter for a while, then taper it to normal.  This would put
the same amount of power into it as originally.  Bruce Roe