Rich1374670x

CCC quadrajet , what is the purpose of this. It doesn't seem to connect to anything.

sofakingdom

iTrader: (1)

Should have a wire coming from the ECM. (in the ECM harness, not the main bulkhead connector one)

It serves several purposes. In stick-shift cars especially, it's an emissions device; holds the throttle from slamming completely closed in between gears and belching a cloud of hydrocarbons, only releasing after the RPMs come down to 1300 - 1400 or so. It also holds up the throttle when the A/C is on. It can't "kick" the throttle by itself, but only acts as a stop above the normal idle speed screw.

Rich1374670x

I noticed that it does not hit the throttle linkage until I give it gas. Then the piston extends to hit the linkage. After I take my foot off the throttle, it goes back in. My question is when it is extended it just barely hits the linkage. Should it hold the throttle slightly open?

sofakingdom

iTrader: (1)

That's more or less what it should do.

Try adjusting it until it does what I just described. It also energizes when the A/C is on; the idle under those circumstances will probably be a shade higher than with it off. Just play with it and see what it does.

Rich1374670x

It just screws in and out? I can hear it to as soon as I give it gas.

fteufert

I use it for a slightly higher idle when the car is not fully warmed up, or after a ht start.

It is threaded, and can be turned in and out to adjust the idle.

In the past, I also used it to set my idle, this way when I turned the car off it would stall immediately and not sputter and run on.

It's main purpose is to bump up the idle when the AC is turned on

sofakingdom

iTrader: (1)

Its main purpose is really emissions control.

Curb idle should be set to whatever the sticker says, with any minor adjustment you might want to make (usually 650 - 700 or so out of gear), then the stop solenoid should be set to something around 1300 - 1400 RPM. Its proper operation is, when the engine is at cruise speed it should be extended; when you take your foot off the gas, the linkage should rest against it, and the RPMs should decrease to somewhere near that point; and then when the correct RPM is reached, the computer drops it out, allowing the idle speed to return to curb idle. It should be all but undetectable in normal operation.

It does also, as a side effect, raise the idle when the A/C is on. It often has too much "authority" in this condition, causing the idle speed to go too high. It may take a bit of playing around to get the A/D idle to a suitable point while also adequately performing the intended emissions function.

Older (70s) cars used a similar solenoid, except it was energized at all times the key was on, to establish curb idle, and then when the key was turned off, it let the idle drop to 400 RPM or something, to prevent run-on. That is not what the one on the CCC cars is intended to do.

fteufert

I agree Sofakingdom, and I am more familiar with the older usage of them, as all my 2nd gen Firebird's had them (even without A/C in many cases).