idle adjustment 575 sci
 

Is the idle adjustment electronic? 2004

it should be controlled by the PCM

The throttle blades are adjustable, but the idle rpm is controlled by the PCM. What kind of problem are you having? I have had to replace the IAC's on mine a couple of times when it got to idling too high when coming off plane

Mine idled high after coming off plane and stumbled going into gear. I cleaned the IAC's and it was better....for a while. I'll replace them next summer. Anybody have a GM part number?

I have a new one in the box at home. I will get it for you later today

The ecm has a desired idle speed. If you adjust the throttle blades, the ecm will counter with timing changes and/or IAC position. It will do it's best to hit the desired idle rpm, even if that means adding 15* of timing and opening the IAC all the way. Are you having an issue in neutral or going into or out of gear?
Eddie

It idles about 200 rpms lower than i want . Push the stick forward and it idles where i want

GM part# 17113099
AC delco # 217-429

Push the sticks forward and you are opening the throttle blades and throttle position switch together, why do you want 200 more rpm at idle?

Cause one motor idles 200 lower than the other. Bump it up and they sound exaclty the same.
It also sounds a little tiny bit loaded up at low idle.

Also the stick has to go forward about 1/2 to 3/4 of an inch before any rpm change

you have something out of wack,maybe tps is going bad,maybe 1 or more injector,s need cleening&flow checking.maybe eddie will have more ideas.

Sounds like the throttle stop screw may have backed off. You really need a scan tool to set the TPS. You really can't do it properly with a volt meter. Hook up a scan tool and see what the TPS reading is. Slowly advance the throttle and see if the TPS registers immediately. If not, you can open the throttle blades a little with the stop screw. You can open it as needed to get the correct idle as long as the TPS doesn't start to register. I like to set the throttle blades where the engine will idle at the desired rpm with the IAC open about 20 counts or so.

If you open the blades to far, with the TPS still at 0, then the ECM will take out timing to get the idle down. If you have it idling and the IAC is closed all the way, you don't know if you are right where you should be or open too much. If too much, the ECM will pull timing and the engine will be lazy and have some lag going in and out of gear. With the IAC open a touch, you know the throttle blades aren't open too much. On the flip side, if the blades are closed too much, the engine will idle on the IAC and you won't have any IAC left to open when you put it in gear. It will stumble, idle low and possibly kill.

Eddie

Eddie. Why aren't you here in Cali.. No wait . I know . Cause too much horizontal snatch..lol!! I will quote you so i don't lose this info. Then I will look at the butterflies. Probly compare them to my Good motor and Go from there. I will check back to this thread and see if it's more than that I can do . If It's Throttle Position sensor or something in the mapping or fuel mixture, I 'll Probly pay Gordon to come down or take my boat up to LA. Thanks !!

I don't have anything against horizontal snatch.....just can't let them go down a water slide. Be like.....brrrrrrrrrrrrpppppp all the way down.
Do you have access to a scan tool? have any buddies with one? I would think someone around there has one. That would be a big help in narrowing it down.
Let me know if I can help in any way.
Eddie

This...

Id make sure the throttle plate is moving right when you come off the throttle stop, linkage could be out of adjustment

My throttle levers move forward one click without raising rpm, after that it's all fun! Yes, it gets to WOT.

Adjusted the idle screw a bit. All it took :)