idle issue

[datzbruh]

New to posting, not to the site. I have been looking and looking, but cant seem to find the answer Im looking for. Here is my issue:

 

On cold starts the idle will be high, about 1800 rpm. it will stay there until I kick the throttle slightly, then will drop to a 'normal' idle at about 850-900. As soon as I put it in gear and give it gas, the idle will climb up to around the same 1800 rpm until I kick the throttle again to drop it back to 'normal' (850-900 rpm). this will happen during any type of driving. I will throw it in neutral to coast and the rpms will stay high until I "blip" the throttle to bring it back to normal. this will happen with a cold or warm engine. Checked for vacuum leaks, and dont find any. Idle mixture is adjusted with vacuum gauge at its highest point. Throttle cable seems fine. Im at a loss here. Basically, the idle will stay high until I blip the throttle. Why would that be?

 

car is a 82 720 with z22 and 5 speed. Thanks in advanced. 

[datzenmike]

Sounds like the fast idle cam is stuck or the choke is not turning off. This is a 720 so lets check the choke first, With the engine thoroughly warmed up take the top off the air filter and have a look. BTW 1,800 to 2,200 RPM is normal for a properly functioning fast idle.

 

You should see the choke plate vertical like this...

 

Not like this, or partly open...

 

Next is the fast idle cam. That plastic thing with the steps on it should be free to turn out of the way of that set screw when the choke is off. If sticking, best bet is to liberally spray everything back there with WD-40 and move all linkages by hand if you have to. Try holding the throttle half open to free any interlocks that might prevent movement. Do all the linkages to the choke and anything that moves.

 

 

 

[datzbruh]

Thanks, datzenmike! 

 

Checked the choke while fully warmed up and it's open like the first picture. Then moved that plastic thing. It moves freely, doesn't bind up or anything. Sprayed the parts with wd-40 and am still getting the high idle as soon as I go into gear and put it in neutral. 

 

On another note, it's hot out today, and the idle sits high. Even after blipping the throttle to calm it down. It still idles around 1300 rpm. Also noticed that on first start up, the idle is normal, about 750-850 under the hot sun. But, as soon as I put it into gear, the idle kicks up again, until I blip the throttle to bring it down again. 

[datzenmike]

Automatic???

[datzbruh]

5 speed

[datzenmike]

On 7/25/2019 at 5:25 PM, datzbruh said:

New to posting, not to the site. I have been looking and looking, but cant seem to find the answer Im looking for. Here is my issue:

 

On cold starts the idle will be high, about 1800 rpm. it will stay there until I kick the throttle slightly, then will drop to a 'normal' idle at about 850-900. As soon as I put it in gear and give it gas, the idle will climb up to around the same 1800 rpm until I kick the throttle again to drop it back to 'normal' (850-900 rpm). this will happen during any type of driving. I will throw it in neutral to coast and the rpms will stay high until I "blip" the throttle to bring it back to normal. this will happen with a cold or warm engine. Checked for vacuum leaks, and dont find any. Idle mixture is adjusted with vacuum gauge at its highest point. Throttle cable seems fine. Im at a loss here. Basically, the idle will stay high until I blip the throttle. Why would that be?

 

car is a 82 720 with z22 and 5 speed. Thanks in advanced. 

 

 Disconnect the throttle cable and rev it up and slowly release and let the RPMs down. Does it hang up and rev high or does it return to proper idle???

 

If it returns normally the cable may be too tight or it's sticky. If it remains on fast idle the throttle shaft may be worn and the throttle plate hanging up on the inside of the bore.