My '86 Trans Am has been acting really weird lately. It'll idle anywhere between 600rpm to 1500 rpm. Sometimes if I romp on the gas real hard it'll return to a normal idle. I was poking around under the hood today, no vac leaks that I could find. I did notice though, that the carb linkage wouldn't return down to the idle stop unless I disconnected the pigtail on the left hand side of the front of the carb. Once disconnected, the idle went exactly where it should be. When I reconnect I get a clicking noise from somewhere ontop of the intake, I haven't been able to find out where it's coming from. But it's a pretty rapid clicking noise. Anyone have any ideas on what's going on?

 

The rapid clicking noise is the mixture control solenoid. Without it, the carb is going full-rich, which is why the RPMs dropped.

Sounds more like your kicker solenoid, which raises the RPMs for the load the air conditioner puts on the engine at idle when turned on. But, it shouldn't be making a clicking noise, nor should the mixture control solenoid stop cycling when the kicker solenoid is disconnected.

Sounds weird. Something must be going on you're not aware of.

 

Sounds similar to the way mine runs. I just figured it was normal. Mine idles high when it gets hot (1000-1100). But, shut it off and start it back up (hot) and it will idle low (600-800). My a/c doesn't work, hole in condenser.

Car: 86 T/A LG4 all stock, Auto trans.

 

Nope not the kicker that was the first thing I looked at. What controls the mixture control solenoid? Maybe something in that line is messed up?

 

The ECM controls the MCS.

Have you ever checked the MCS dwell?

 

Hmm....nope can't say I have. Is this the jobber inside the carb?

 

i get that same clicking noise but mine wont idle at all or it idles around 1500 i just switched to manual choke and the front butterfly valves wont close at all its like somthings stuck because even if i push on it it doesnt close

 

The MCS is inside the carb, yes. It is first adjusted via stops when the carb is apart, and then fine adjusted for "dwell" or duty cycle with the idle air bleed.